PDA

View Full Version : I have a cunning plan* for a lathe bed regrind



form_change
11-18-2010, 04:06 PM
My lathe bed has seen better days and could do with some attention. I'm a while off doing something about it but came up with a plan that I thought I'd toss out there for suggestions and comment.
I have two issues. One is that one of it's many previous owners didn't bother keeping the oiling mechanisms full and so there are visible score marks on the ways. (Someone even tried grease as a way lubricant - in the oil pump reservoir...) Measuring using one of Connelly's techniques I'm getting dips of 5 to 8 thou. The other thing is that the tailstock ways are worn enough such that the headstock and tailstock axis are not vertically co-incident. I've snapped drills discovering this.
Sending the bed off for a regrind is out as that would be thousands. The plan is to make up a frame that will bolt to some pretapped holes in the side of the lathe bed and using some linear rail, make up a carriage that I can attach a tool post grinder to. I'll use that to take out the major imperfections and then use a carbide scraper and straight edge to do the last bit.
Has anyone tried this ? Anyone see any obvious holes in the plan, or ideas for improving it?
(The reason sending the bed away is out is that it is 6ft long and weighs lots - no one around here has a way grinder big enough. However, it's a CVA so I think worth spending the effort on.)
Michael

*Apologies to those not familiar with 'Black Adder'

small.planes
11-18-2010, 04:25 PM
Sounds like a cambridge fox ;)
More seriously head over to practical machinist and look in the monarch forum, a bloke in the US reconditioned 'the wreck' using a similar technique.

Dave

gregl
11-18-2010, 04:31 PM
First, I'd want to know if the wear in the ways is showing up in the work. Seems to me that 5-8 thou is a very small amount. Visible score marks are different from overall wear. A score in an otherwise good surface that isn't throwing up a burr shouldn't have any effect on accuracy.

Second, could the tailstock issue be dealt with via shims between the tailstock slide and the base?

Evan
11-18-2010, 04:36 PM
How do you intend to ensure that the temporary carriage is coaxial with the headstock to better than .001" along it's length?

Mcgyver
11-18-2010, 04:40 PM
the problem has not gone away.....that you currently don't have anything flat to run the grinder along. What are you going to bolt to the linear rail to? if what ever its bolted to isn't flat neither will the rail be. I think it would be very hard to make an infrastructure large and strong enough and perfectly aligned in two directions; essentially you're talking about making a lathe way grinder; no small order....and it has to be big enough and rigid enough to work across the width of the bed

Since you plan of finishing via scraping, that means all precision will come about from the scraping which means you either have or will acquire the equipment and knowledge on how to scrape V ways etc.....in other words all the grinding would do is be used for roughing away the worst of it? If so, instead of grinding could it be sent out and milled locally then you scrape for precision? Even if hardened, carbide or ceramic might work.

I've got the same situation; no matter how i come at it, for a high quality job, it keeps coming back to either scrape it yourself or send it out to someone equiped to properly grind beds and damn the cost.....but secretly I do hope you figure it out because neither of those options is super appealing to me either :D

John Stevenson
11-18-2010, 04:50 PM
For anyone not familiar with a CVA lathe it's a clone of a 10EE.

http://www.lathes.co.uk/cva/index.html

.

gnm109
11-18-2010, 04:55 PM
Sounds like a cambridge fox ;)
More seriously head over to practical machinist and look in the monarch forum, a bloke in the US reconditioned 'the wreck' using a similar technique.

Dave


That would be "Beckley". I read his thread on the rebuild and restoration of a very large, vintage Monarch lathe. The amount of work, detail and skill involved was simply astonishing. He's apparently got somethiong like 40 years of experience and from the look of that thread, it took every bit of his ability to make it right.

I would think that using a tool post ginder to level one's ways would be doomed to failure. There's a reason why the experts will scrape a lathe back to flat rather than grinding them.

I'll leave this one to the experts.......:)

JoeLee
11-18-2010, 05:01 PM
You'll never get it right......... You also have to contend with the angles of the V's as well as the spacing and everything the previous posters mentioned. If you have ever seen the size and design of a machine that grinds beds you would understand why a home made rig would be next to impossible.

JL.............

JoeLee
11-18-2010, 05:06 PM
Here is a link to a place about 50 miles from me that rebuilds machines. There should be several pics of the bed grinding machine. It's quite elaborate. I've seen it in action.

JL...................

http://www.galleryofmachines.com/page1.htm

.RC.
11-18-2010, 05:17 PM
Have you got a price to get it ground?

I know people have had Hercus beds reground for around the $300 mark... Heavymech in Adelaide advertise a slideway grinder as part of their capabilities.. http://www.heavymech.com.au/EquipmentCapacities/tabid/242/Default.aspx . Hercus can also grind beds but probably not the length you have.. At the very least I would try to ring them first, tell them you want a grind only and you will refit the saddle and tailstock yourself..I assume the CVA headstock sits on the V-ways like the 10EE so you would not want them touched either...

Of course they could be like one place I contacted in Qld and just not want the job and rough quote $10 000 like I was..

JoeLee
11-18-2010, 05:29 PM
The place I posted the link to wanted 7K to grind the bed of my clausing 5900. I believe that price included refitting the head stock, carriage and tail stock to the bed.

JL...............

J. R. Williams
11-18-2010, 05:45 PM
Michael
Check with John Hoff at the Home Metal Shop Club. Several years ago John did a similar project.

JRW

Peter.
11-18-2010, 06:04 PM
How on earth does someone manage to wear-out tailstock ways to any serious degree?

PeteF
11-18-2010, 06:20 PM
Michael, contact Steve at Hercus. I'm pretty sure they can do grinds that long and I think you'll find it's cheaper than you may be imagining. I guess the ways are hardened and I feel you're setting yourself up for a true Black Adder episode with your cunning plan, though Baldrick would be proud!

Peter, I believe tailstock ways are pretty common to wear, particularly their front halves, when being slid along an unlubricated bed.

Pete

Evan
11-18-2010, 06:44 PM
You'll never get it right......... You also have to contend with the angles of the V's as well as the spacing and everything the previous posters mentioned. If you have ever seen the size and design of a machine that grinds beds you would understand why a home made rig would be next to impossible.



I think it is possible to do well although far from easy. I wouldn't use a method that depends on the bed to support the grinder. The axis of the headstock is the sole reference for this job and that is how it must be approached. To begin with a good sized diameter of hydraulic cylinder tubing can serve as the basis for a jig. The essential part of the system will depend on supporting it in the chuck and at the far end of the bed way with a bearing system that is able to be adjusted to ensure that it is in alignment with the headstock axis of rotation. By using a laser mounted in the tail end of the spindle with an appropriated adaptor the coaxial alignment can be assured.

This is the laser device. It is used to align the optical axis of a telescope.

http://ixian.ca/pics8/coll1.jpg

The collimator is attached to the left end of the spindle and a beam is projected through the spindle to a target. The spindle is rotated and the laser alignment is adjusted with the setscrews until the spot stays in one place on the target. That aligns it with the axis of rotation precisely.

Then a mirror holder is made that can be attached to the far end of the hydraulic tubing in a manner that ensured the mirror holder is concentric with the tubing. That isn't difficult since the ID of the tubing is very accurate. A small mirror is installed in the mirror holder so that it is exactly normal to the axis of rotation and then the holder is installed in the tubing.

The tube and mirror assembly is installed in the chuck and supported by the shop made bearing holder at the tail stock end of the lathe. The tail stock itself might be used for this if it can be shimmed to bring it into alignment with the headstock.

The laser beam is sent down the tube and reflected by the mirror to a screen in the collimator. The screen is set at a 45 degree angle so it can be viewed through the provided hole. The screen has a small aperture in the centre that permits the laser beam to pass out of the device. The alignment of the tube is obtained by watching the location of the laser beam spot on the screen. When the slightly diverged spot exactly produces a ring around the aperture on the screen it is then going out and coming back in alignment with the axis of the spindle.

At that point you have a very sturdy reference in the form of the hydraulic tubing that is in alignment with the spindle and can serve as a linear way for a grinder. The rest is basic mechanics.

aboard_epsilon
11-18-2010, 06:57 PM
How on earth does someone manage to wear-out tailstock ways to any serious degree?

i was thinking that .

it probably isnt ..its probably the tailstock barrel worn.

all the best.markj

noah katz
11-18-2010, 07:21 PM
Somewhat tangential, but any reason acetal wouldn't make as good a material for ways as it does for leadscrew nuts?

Easier to grind for sure.

vpt
11-18-2010, 07:23 PM
Just use a belt sander.

http://www.sandertoolreviews.com/img/belt-sander.jpg

.RC.
11-18-2010, 07:32 PM
How on earth does someone manage to wear-out tailstock ways to any serious degree?

Easily, a lot of use... The tailstock ways on one of my lathes are very worn about 2 feet from the headstock...

AllThumbz
11-18-2010, 07:38 PM
+1 on what .R.C. said. Your statement:

"Sending the bed off for a regrind is out as that would be thousands." is not necessarily true because I have heard of people having it done for $500 or about $100 per foot or something like that. Then they shim up the bed using some special material made for that purpose. I'm obviously no expert, rank newbie, but I would check into prices to re-grind it flat. You may be surprised,

rkepler
11-18-2010, 08:14 PM
When I had my 10EE bed ground (and some other bit) almost 10 years ago it was a bit less than $700. But I took it in during a slack time and I understand that the price is a lot higher now.

I could see how you might align some linear ways to the ends of the bed and guide a grinder with them with some degree of accuracy. You'd want to match the angles of the existing Vs and rescrape the headstock back into alignment with the ways when complete - you have to do that anyway even if the head mounting points aren't reground unless you manage to keep the alignment in the ways (possible with scraping, a lot harder with grinding I would think).

But the grinding is going to be really tedious and the ends will likely have to be touched up a little with a scraper as there's going to be some dip in the middle - unless you have multiple support points on the linear ways. Seems to me that would induce other errors, so it might be a 'six of one' and half-a-dozen of the other choice. Scraping is going to be fun with the hardened ways.

There's a couple of different writeups on the process on the PM Monarch forum.

ammcoman2
11-18-2010, 08:22 PM
A few years ago a guy in our Model club gave a talk on how he re-ground the worn bed on his lathe.

Basically he made up a trolley on which he mounted a huge toolpost grinder. The trolley ran on skateboard bearings that ran on the machined section of the bed (between the V-way and the flat section (both front and back). There were also bearings located on the underside of the bed where the carriage clamps are and they were mounted in a cam arrangement so he could set them up with some pre-load against the upper bearings.

He showed slides of the job being done - there was a great showering of sparks. Being a skilled tradesman, he made it sound quite straightforward but he said that the machined reference surfaces he used were very accurate.

The carriage etc, were built up with Moglice (I think).

Geoff

ammcoman2
11-18-2010, 08:23 PM
I forgot to add that there were also bearings pressing against the outer edges of the bed - also preloaded.

Geoff

Black_Moons
11-18-2010, 09:10 PM
Shim the tailstock to bring it up to height, its not likey its ways are worn(How often does the tailstock move??), lots of tailstocks are not properly aligned however.
5 mil drop in the carriage ways is not a big deal either on larger diamiter parts. Much less then 5 mils error in the resulting work.

Insure any burrs on the ways are CAREFULY ground down with a hand stone (someone here might have the proper method)

And just keep it oiled from now on.

That, or spend $$$ and get it professionaly reground and skip scraping.. This is not a job you want messed up, Unless you allready have had PLENTY of experiance scraping things.

Consider it a beater lathe if you must, do your sanding/polishing/woodwork/etc on it when you get a better lathe later on.

form_change
11-18-2010, 10:14 PM
Some added information for the discussion-
For those not familiar with CVA's they are a development from the Monarch 10ee round dial lathes, so are a top notch toolroom lathe. I only have room for one lathe and this is it. Fully assembled they weigh 1.5 metric tonnes. The bed is attached to a cast base, so to move it means moving around 500 to 1000kg of cast metal.
I'm not joking about the $1000's to get it ground as the rigging equipment (hired) to get it into position was $250. A truck to Melbourne (the nearest place with grinders big enough to take the whole machine) would be several hundred dollars (Melbourne is 800km (500 miles) away). I'm getting close to $1000 just in transport costs.
This lathe dates from 1957 so has seen some work. The tail stock has an oil reservoir which when I opened it up had a lump of thick grease in it. Essentially it was being slid on the bed in a dry condition. The score marks all stop at around the same place so I suspect that for a while anyway it was used for repetition work in an unlubricated state (sacrilege!).
I've looked at the Monarch posts on PM which is what has me wondering what I can do. In this case I haven't got a way that I can rely on to use as a reference so it's a matter of finding something else - hence the linear bearing bolted to a frame attached to the machine as a starting point. From memory the PM poster (beckley?) used carbide tips on a carriage to do the bulk removal but had something to work from. The other option is make up some dummy ways out of 'softer' steel and scrape those in. I have scraped slides before, so the prospect doesn't scare me. However, the ways are hardened so I don't want to spend days trying to remove 'excess material' - and we are talking thous, not mils.

.RC.
11-18-2010, 10:44 PM
Hercus and Heavymech are in Adelaide.. Heavymech have a 2.7m (8ft I guess) churchill way grinder listed as part of their inventory...

The lathe would most certainly be worth rebuilding...

A random youtube link for some ideas..


http://www.youtube.com/watch?v=GlbKtYJJw-s

J Tiers
11-18-2010, 10:47 PM
The way I see it is that you are , right now, basically guessing at the condition.

You are pretty sure it isn't good, but you don't know how good, or bad , it is. You threw out a figure of 5 to 8 thou in terms of "dips" in the ways, but it is NOT clear how you generated a reference against which to determine that.

Reason I say that is that if you can find a reliable and useful reference to check the alleged dips against, then the very same reference may suit to determine overall flatness. Once you have one flat and straight "known", the rest of the problem becomes much easier, as you can reference it, level from it, etc.

At the moment, without further explanation, I am wondering how you KNOW the T/S ways are that bad.... You may have a good reason, we just haven't seen it.

The T/S dip is clearly NOT a good reason, as it is far more likely that the ram or the bore of the T/S is worn.

I am not saying it ain't so, I am asking for a bit more of the evidence.

That all said, A CVA is a nice machine if in good shape (going by reports, I've never used one). It could be well worth it to go ahead and have it ground. But I know from personal experience that all is not lost if a machine has some wear.

Then also, do you plan to check the ways on the grinder the low bidder is gonna use on your machine? How do you know that you will not get a faithful negative reproduction of the bumps and humps in their grinder ways ground into your bedways?

My thought is that you need to dig up someone with a long straightedge, and you folks should have some "fun with shims and paper strips" to determine what is up (or more likely down) on the ways. After that. you will have a "map" of the ways, and can make some decisions. Without doing some sort of a survey, you have nothing to really work with. Your "connoley method" may or may not be valid on your machine, depending on what method you mean.

4GSR
11-18-2010, 10:48 PM
Form_change,

I generally hang out on the Practical Machinists forum.

I'm fixing to regrind the bed ways on my 20" Lodge & Shipley lathe using a "sled" type fixture that is guided by un-worned portions of the bed ways.

If you are interested in detail what my fixture involves, send me your email address and I'll send you a pdf file of the layout of the fixture I've built. I am planning on using one of my woodworing routers for the grinder.:eek: I'll know in a few weeks how it turns out.

I don't know if private messages can be sent on this site, if not go to PM site and send me a message.

Ken

beckley23
11-18-2010, 10:58 PM
I scraped the inside flat way first, starting at the headstock end and working to the tailstock end. I then scraped one face of the inside V way, the one I determined to be in the best condition, then the other face. Once I had the necessary alignment between the inside faces, mainly being parallel, I then built the sled to be used in the planing/shaping of the outside ways to remove the bulf of the material. Those ways were scraped into alignment with the inside ways. I used ceramic inserts, a lot of them, as the cutting tool.
Needless to say, this was a very long process. In addition you are going to need a lot of special tools, #1 being a BIAX scraper, a surface plate big enough to make a suitable straight edge, special V blocks if the CVA's V ways are like the EE's, a 65* included angle, Master Precision Level, etc, etc. I already had 95% of the necessary tools to do the job, so my cash outlays weren't much. If you're starting from nothing, then you've got some decisions to make.
If you have never done this before, think long and hard about this project, and to be honest this is not a project for the beginner, IMO.
Here's a link to the ""Wreck" Update".
http://www.practicalmachinist.com/vb/monarch-lathes/wreck-update-146913/
Harry

TexasTurnado
11-19-2010, 12:31 AM
Here in Texas, the cost of precision grinding is not what you are thinking: I recently had a Colchester 15 x 50 bed ground for slightly less than $1000, including 8.5% tax. This included all necessary surfaces, including the under side of the outside ways. The work was done at Commerce Grinding in Dallas on their 300 inch Waldrich Coburg and I was very pleased with their workmanship and customer relations. Here is their website if you are interested: http://www.commercegrinding.com/index.html. There were two CNC lathe beds in line before me, as well as several other items, but I only had to wait about 10 days to get it back. I didn't get to watch mine being done, but did see the first CNC bed being ground while I was there - very impressive to see that large machine whisk the bed back and forth, removing a small amount each pass! :D

darryl
11-19-2010, 02:05 AM
Amongst other things, I'm concerned about the hardened ways- as you 'plow through' the metal, you'll be encountering a difference in hardness. This has potential to make a difficult job even more exasperating. Although, another way to look at it is that if the surfaces were all brought back to 'level', the thickness of the hardening should also be about the same. Maybe you can find a spot to test that won't be used later, like the extreme right end of the rear way. Grind a divot and keep checking it for scratchability as you go deeper and deeper. Obviously you need to go easy on the grinding so you don't anneal the spot you're working on. If you find that the hardness goes in say 20 thou, you might then feel safer grinding off 10 thou all along the ways. But if you find the hard layer to be only 10 thou thick- firstly you're going to know that all the hardness is going to get ground off if you have to go 10 thou deep in order to level the ways for the entire length of the bed. Secondly, there's probably going to be some anomalies with the grinding operation when it goes from hard to softer steel. I guess this is where scraping has the potential to fix it all up-

Any way that I can see to get this done in a home shop is going to be a lot of painstaking work, with no room for errors.

Evan
11-19-2010, 06:42 AM
Question for all:

How do the commercial bed regrinders develop a reference to the spindle axis when setting up a grinding job?

Greg Q
11-19-2010, 07:26 AM
I wonder if they do? Since the headstock does not see any wear/damage I imagine they assume that a straight co-linear bed will automatically result in a co-linear spindle when the headstock is remounted. Although I do read of shims being installed under headstocks. I'm a few thousand Km's from my nearest copy of Connelly right now so I can't give you his answer.

My lathe's headstock is cast integral to the bed, so I must mount a test bar (hollow, large diameter), zero it, and then level the lathe so that the test bar is dead level with zero runout. Using other levels and straightedges I plan to check progress when scraping the flat ways to ensure parallelism. Work on the vee ways can be done from there, possibly with the use of a King Way Alignment tool to ensure they remain parallel with the spindle.

oldtiffie
11-19-2010, 08:36 AM
So far, no one has considered whether the undersides of the apron/carriage and tail-stock should be re-ground.

If not - why not?

Why not consider regrinding the male and female dove-tails in the cross and top slides?

If it were me, I'd do a cost vs benefit analysis of grinding vs a new lathe.

I'd pretty sure too that if it were me, I'd opt for a new lathe.

But I'd seriously consider leaving the lathe "as is" and make the most or best of it.

0.008" is not a lot of wear really and can easily be "worked around".

A lot of so-called "tail-stock misalignment problems" are as much to do with the quality of the drill chuck (or the lack of quality) as it is tghe fault of the tail-stock.

Drills tend to self-centre if in a tail-stock.

I'd suggest putting the drill chuck in the head-stock morse taper and check it for eccentricity and alignment.

I have my TS quill - with a centre drill in the drill chuck - extended as far out as I can get it as it will at least partially counter the effects of misalignment.

Normal twist drills will follow the centre-drill and will flex quite easily as they are quite flexible.

My first drill after the centre drill is a 1/4" drill as it saves "web-thinning" the next an subsequent drills.

If I have a problem with a taper in a cylinder and if it is within tolerance, I leave it "as is" as it will do the job.

If it needs to be more parallel, and if it suits the job, I use a lathe file and emery paper.

If it is an internal cylinder, I use either a "3-point" or "half-round" (bearing) scraper.

All of this depends on the job requirements and the ability of the machinist.

If my lathe would not perform satisfactorily and needed a lot of cash and remedial work, I'd junk it and get another.

J Tiers
11-19-2010, 09:47 AM
Question for all:

How do the commercial bed regrinders develop a reference to the spindle axis when setting up a grinding job?

Why should they?

Unless the headstock is cast-in, the only real requirement is that the various surfaces shall be parallel and flat (as appropriate).

JoeLee
11-19-2010, 09:48 AM
Question for all:

How do the commercial bed regrinders develop a reference to the spindle axis when setting up a grinding job?

They don't from what I saw as I watched the person set up a bed at the rebuild shop I posted the link to. They indicate off the untouched portions of the bed, like under the head and the very end where the tail stock sits, outer edges where nothing rides. The bed is also only supported where it normally sits on it's base. Then they have to scrape in the bottom of the head to the newly ground bed for alignment.


JL....................................

Evan
11-19-2010, 09:48 AM
I wonder if they do? Since the headstock does not see any wear/damage I imagine they assume that a straight co-linear bed will automatically result in a co-linear spindle when the headstock is remounted.

The reason I ask is based on my South Bend 9" lathe. The headstock is clamped to the bed using the rear tail stock way and the front tail stock flat as the locating reference. It isn't referenced directly to the carriage ways. Since this is a very common lathe this can't be considered unusual. This means that the carriage ways can only be referenced to the headstock spindle indirectly if the tail stock ways are used as a reference to the spindle.

That would allow for tolerance stacking in a situation where that is the last thing you want. Further, the carriage ways are over constrained by the fact of being double Vee ways. That means they must be coplanar on THREE sides, the top and each side of the Vee ways to be considered parallel. Even a slight error in the relationship of each way to the other can cause a large magnification of that error as the carriage will ride up the vee if the angle or spacing varies at all.

The South bend lathes are famous for the accuracy of the hand scraped ways since extreme accuracy is required to make such a double vee system work. The difficulty of manufacturing such a bed is the reason that many lathes use a single constraint way system with the other side flat such as the tail stock ways on the SB and the many examples of flat ways such as Atlas lathes.

So, back to my question. How is the spindle axis referenced to the carriage ways, in particular on a lathe with ways like the SB?

edit: I seem some posts that were made while I was typing this. If you were to scrape in the headstock on a SB to align it with the carriage ways it would disturb the alignment to the tailstock. Then what?

J Tiers
11-19-2010, 09:54 AM
Deleted duplicate.....

rkepler
11-19-2010, 09:58 AM
So far, no one has considered whether the undersides of the apron/carriage and tail-stock should be re-ground.

If not - why not?

I think most folks realize that it's a given that the headstock, tailstock base and saddle ways have to be refitted to the newly ground bed. You don't grind them, you scrape them to match the bed (or, in my case of my saddle, machine in a gap and use Moglice to both raise it to the original height and fit it to the bed).


Why not consider regrinding the male and female dove-tails in the cross and top slides?

I did have the saddle cross slide ways reground as well as the taper swivel sides where the shoe rides. The cross side had to be built back into height with way material, the compound wasn't significantly worn and was only rescraped for contact.

I also had the top of the saddle and the cross slide cleaned up with a 'rough' grind.


If it were me, I'd do a cost vs benefit analysis of grinding vs a new lathe.

I CVA is the same class of lathe as a Monarch 10EE, very high quality and capable of very nice precision as well as some pretty serious cutting. I've turned off the .0001" lobes from centerless grinding as well as taken .200" DOC in A2.


A lot of so-called "tail-stock misalignment problems" are as much to do with the quality of the drill chuck (or the lack of quality) as it is tghe fault of the tail-stock.

Drills tend to self-centre if in a tail-stock.

I'd suggest putting the drill chuck in the head-stock morse taper and check it for eccentricity and alignment.

One problem I've seen with this design is that the front edge of the tailstock base takes a lot more wear than the back edge, mine had .005 or so. I scraped the bottom back in to a nice contact with the ground bed (making the flat top level) and simply shimmed the top back into height - took a .007" shim when it was all said and done.

The right way to check the tailstock is with a parallel test bar checked when the quill is retracted and extended, that will eliminate the 'nodding' that comes with unequal wear on the base.


If my lathe would not perform satisfactorily and needed a lot of cash and remedial work, I'd junk it and get another.

A lot of home shop machinists like to buy cheap and repair, some even when it doesn't make financial sense (except that you can get into nice hardware with dollar averaging rather than a one-time purchase). Something like this lathe can't be bought new. A 10EE from Monarch as a 'reconditioned' lathe will set you back $25K+ when buying one and rebuilding it to the same standard will problem set you back $6K or so.

J Tiers
11-19-2010, 10:03 AM
If my lathe would not perform satisfactorily and needed a lot of cash and remedial work, I'd junk it and get another.

Might be short-sighted economy.

"A lot" is a variable quantity.

The OP has a machine that would, if new, cost $80,000. Refurbished by the factory, similar machines go for amounts in the multi-tens of thousands of dollars.

This is not a cheap Atlas "throwaway".

If he could spend several thousand and get performance even close to the refurbished performance, it would be a bargain. If he cannot afford to do that, then he has a choice...... live with it, sell it to someone who wants it, or scrap it for peanut money.

To replace it with new chinese of similar size will cost an amount sufficiently similar to the re-working cost as to make it a question. Possibly $5000 or so, vs something around $8000 for a re-grind/realignment.... And you buy a machine that is, frankly, not even close in potential quality.

No, the scrap price of the CVA won't come close to paying for it.

Replacing it with a used machine is to get another worn-out piece of scrap, to borrow the description given by some here..... and will certainly buy a machine with similar wear amounts. Its just "churning your money", making no improvement.

Regrinding starts to sound like a practical approach at that point, especially since IIRC the job was described as including re-aligning the H/S & T/S at least.

We know your choice, Tiffie, but you have little or no regard for fine machinery as an object, and you seem to have unlimited cash to replace equipment that you admit yourself you don't use for gain.

JoeLee
11-19-2010, 10:04 AM
I was explained to me that after the bed regrind and the saddle refit, cross slide etc. and the machine was all put back togather and ready to run a test cut was preformed, if the test piece did not meet thier specs the head was removed and the bottom of the head was scraped in to compensate for any error in cut.

Look at the second picture down and you can see the double tool post grinders set up to grind one side of both V's in one pass.

http://www.galleryofmachines.com/page1.htm

JL......................

rkepler
11-19-2010, 10:07 AM
So, back to my question. How is the spindle axis referenced to the carriage ways, in particular on a lathe with ways like the SB?

In my case (and the sequence called for in the MTR) I rescraped the tailstock base to the new bed (good contact on the base and level to .0002" both ways on the flat top) then used it as a carrier for an indicator. The indicator rode on a parallel test bar in the spindle, and the headstock base was scraped to bring the axis of the spindle in line with the bed ways (since they were ground at the same time they were themselves parallel). Strictly speaking the far end of the 18" bar was left a little high, this to account for the sag in the bar.


edit: I seem some posts that were made while I was typing this. If you were to scrape in the headstock on a SB to align it with the carriage ways it would disturb the alignment to the tailstock. Then what?

I'm not sure which alignment you're asking about - vertical or axial? Vertical you can correct by shimming up the tailstock or scraping it down.

If the ways became non-parallel with the spindle axis during some process then the headstock would have to be scraped back into alignment after confirming that the ways on the bed are truly parallel. For me that was one of the advantages of having the bed ground - I could use it as the 'truth' for the rest of the rebuild.

lazlo
11-19-2010, 10:17 AM
They don't from what I saw as I watched the person set up a bed at the rebuild shop I posted the link to. They indicate off the untouched portions of the bed, like under the head and the very end where the tail stock sits, outer edges where nothing rides.

Like Joe and Jerry say, they don't -- you deliver them a bed without a headstock.

A friend (TexasTurnado) has had two bed reground at Commerce Grinding in Dallas (where Russ and Daryl Bane had their 10EE's reground), and they mark the bed for wear, and then grind the least amount of material to get the bed flat and parallel.

John has some neat pictures of his bed pre- and post-grind at Commerce -- I'll see if I can get him to post them.

JoeLee
11-19-2010, 10:34 AM
Which reminds......... as I think back when I was rebuilding my Clausing 5900. I was fortunate enough to have been put in contact with a retired engineer from Clausing. As I called him a few times, more than a few times during my venture I had asked hundreds of questions. One that comes to mind is spindle bearings and regrinding the bed. He told me that after the bed was reground the head would have to be refitted to ensure a true cut on what they used was a 6" length of steel. So I asked how do they bore the bearing seats through the head and maintain accuracy so all these mass produced machines would be accurate. He told me that teh bearing holes were initially bored undersized, the head was then mounted to the bed and they had a special jig bore machine that rode the bed rails to finish bore the bearing seats. That all made sense to me. This ensured that the spindle was true to the bed. But there was almost always some additional hand fitting that had to be done.

JL.................

lazlo
11-19-2010, 10:56 AM
So I asked how do they bore the bearing seats through the head and maintain accuracy so all these mass produced machines would be accurate. He told me that teh bearing holes were initially bored undersized, the head was then mounted to the bed and they had a special jig bore machine that rode the bed rails to finish bore the bearing seats.

Wow, that means if you take out that taper pin that locates the headstock, you're screwed.

I have a 5914 -- that's a great story!

JoeLee
11-19-2010, 11:03 AM
Wow, that means if you take out that taper pin that locates the headstock, you're screwed.

I have a 5914 -- that's a great story!

Why would you take out the tapered pin?? other than to remove the head. The pin just keeps the head from sliding back under a load. It also would have to be drilled after the fitting was complete.

JL....................

lazlo
11-19-2010, 11:16 AM
Why would you take out the tapered pin?? other than to remove the head.

The head is bolted on the ways -- look at the back side of the headstock.

The whole point of that taper pin is to locate the headstock before you clamp it to the ways. The Clausing engineer told you that the spindle taper was ground in-situ when the headstock was mounted. If you move the headstock, you'll never get it back to factory runout.

Mcgyver
11-19-2010, 11:43 AM
In my case (and the sequence called for in the MTR) I rescraped the tailstock base to the new bed (good contact on the base and level to .0002" both ways on the flat top) then used it as a carrier for an indicator. The indicator rode on a parallel test bar in the spindle, and the headstock base was scraped to bring the axis of the spindle in line with the bed ways (since they were ground at the same time they were themselves parallel). Strictly speaking the far end of the 18" bar was left a little high, this to account for the sag in the bar.


Russ, how did you hold the bar in the spindle such that its axis was dead on with the spindle bearings?

Mcgyver
11-19-2010, 11:48 AM
The head is bolted on the ways -- look at the back side of the headstock.

The whole point of that taper pin is to locate the headstock before you clamp it to the ways. The Clausing engineer told you that the spindle taper was ground in-situ when the headstock was mounted. If you move the headstock, you'll never get it back to factory runout.

I don't know that model of lathe - of the lathes I've seen, there are ones where the headstock sits on the V way and that provides the reference for alignment, and the other type where there isn't a V way under headstock. Is this pin an alignment methodology for the later.....because you don't need it for the former?

my DSG I think is the later, haven't figure out how to realign things if i get the bed ground. Currently that's serving as a adequate excuse for doing nothing :D

lazlo
11-19-2010, 12:08 PM
I don't know that model of lathe - of the lathes I've seen, there are ones where the headstock sits on the V way and that provides the reference for alignment

On the Clausing 59xx and 69xx, the headstock is sitting on the tailstock ways. There's a taper pin on the front-left of the headstock to pin the fine adjustment of the headstock. Then a clamp in the back bolts everything down.

Just ran into the shop and took this picture:

http://i164.photobucket.com/albums/u15/rtgeorge_album/Clausingheadstock.png

Mcgyver
11-19-2010, 12:11 PM
then wouldn't the alginment be absolutely constrained by the V way to the V in the headstock :confused:

Stuart Br
11-19-2010, 12:29 PM
On the Colchester Chipmaster, the headstock sits on the flat ways. There is a single locating dowel on the rear bedway behind the spindle nose. This allows the headstock to pivot in the horizontal plane for fine alignment adjustment. The headstock is secured by four bolts. So as long as the complete bed is flat following a regrind, the spindle should be in line in the vertical plane. Adjustment of the tailstock height may well be required to compensate obviously.

rkepler
11-19-2010, 12:34 PM
Russ, how did you hold the bar in the spindle such that its axis was dead on with the spindle bearings?

In the spindle taper, but it could have been held any old way. If you use a round bar of consistent diameter you can find the true spindle axis by rotating the test bar. The average of the minimum and maximum TIR is the line the indicator is taking. (Technically - you could deal with diameter change if you account for it, but non-round would be harder to correct for). Using the spindle taper just makes it easier, you can use a 4-jaw and some linear shafting if that's what you have around.

After the headstock is aligned with the bed ways you align the cross slide perpendicular to the spindle axis and level across the ways. I 'cheated' here with the saddle using Moglice putty by putting fine lead jackscrews bearing on the faces of the V way and the flat - that way I could tweak in the alignment (4-way compliance here - height, level 2 ways and perpendicular) until I was happy with it then just "glue' everything together.

For me the bed grinding was the way to go. Cost was a a couple of days driving and some time hanging with friends. Commerce Grinding in Dallas was very helpful, the owner showed me how to 'hammer in' (flatten) a circular saw blade and I saw my taper swivel being ground on the same grinder that had done my lathe bed. I think they could have ground in a small bus on that table, and there was a 10" long 3" wide swivel having the sides brought parallel, way cool. In the end the bed was precise enough that it became the reference for the rest of the rebuild.

And honestly - I'm one of those guys who could go out and buy a new import lathe and not feel a pinch from it. I chose to rebuild a 10EE because I'd end up with a great lathe that I could point at and say "It was a piece of crap and I fixed it!" I don't have a commercial shop that I have to justify, I have space in my garage where I make steam engines and such. I rebuilt the lathe for the same reason that someone rebuilds a car - for the fun and learning in the process.

JoeLee
11-19-2010, 12:59 PM
The head is bolted on the ways -- look at the back side of the headstock.

The whole point of that taper pin is to locate the headstock before you clamp it to the ways. The Clausing engineer told you that the spindle taper was ground in-situ when the headstock was mounted. If you move the headstock, you'll never get it back to factory runout.

The head stock sits on a V. The pin only holds the head from sliding, it has nothing to do with alignment. Once final alignment is obtained with the head bolted down the pin hole is drilled. If you removed the head why wouldn't you get it back??? I did and mine is OK.

JL...................

lazlo
11-19-2010, 01:29 PM
If you removed the head why wouldn't you get it back???

Same reason that if you change the spindle bearings on a spindle that's been ground in-situ that you'll never match the original run-out unless you regrind the taper.

That's why spindle rebuild services lightly regrind the spindle taper when they change the bearings: nothing is perfectly flat or perfectly round.

Richard Wilson
11-19-2010, 01:50 PM
The head is bolted on the ways -- look at the back side of the headstock.

The whole point of that taper pin is to locate the headstock before you clamp it to the ways. The Clausing engineer told you that the spindle taper was ground in-situ when the headstock was mounted. If you move the headstock, you'll never get it back to factory runout.
Unless you dismantle the headstock bearings, moving the head complete has no effect on runout. alignment possibly, not runout. If the bed ways are good enough to ensure that the carriage travels on the same alignment each time, then surely they are good enough to ensure that the headstock goes back on in the same alignment. I can see the reason why the makers bored the bearing housings in situ originally, but a headstock sitting on vee ways is going to come back on the same alignment each time, why would it not? It will only be off alignment if the original manufacturer or the reconditioner didn't get the bed straight and flat when grinding the ways.

Richard

oldtiffie
11-19-2010, 02:01 PM
The OP is in Adelaide, Australia - not in the USA or UK.

It seems that he is really stuck for room and the lathe under discussion is his one and only lathe and that either removing the lathe or fitting another one in during the period of the refit is not an option.

If that's so, he will be without a lathe during the period of the refit of this lathe - which could be months. Can he do without the lathe for that long?

Irrespective of what some may think, I do like fine machines, but all I really need is one that is sufficient for my needs.

If the lathe bed (at least) is re-ground and re-fitted in situ he is going to have to cover a lot other stuff up for a while at least.

If he is going to have it re-ground by "others" off-site, it seems that his logistics are going to be considerable.

I don't know how physically fit the OP is nor do I know how old he is.

All of these are for the OP to resolve.

John Stevenson
11-19-2010, 02:42 PM
Perhaps the OP wants to use the lathe [ heavens above ] not polish it or take pictures of it.

I look at some of the lathes on Tony's lathes.co.uk web site and in some cases knowing where they were made, what equipment they had at their disposal, and the resultant end product it makes me wonder if they had sat down, been involved in a discussion like we are having here, whether or not they would have just gave up, signed on the dole and not bothered.

We have two posters at least on this board who have made machines.
Evan has done a mill and a lathe with a wooden bed that is accurate to 2 microns in 8 zip codes.
Alan [ Jackary ] has made the step master but I don't think he's posted accuracy results or if he has they are probably only to 3 decimal places.

The above gives me the idea that things can be done if it's possible to get arses un-welded from armchairs.
failing that we can just carry on and let the Chinese do everything.

lazlo
11-19-2010, 02:42 PM
[/I]Unless you dismantle the headstock bearings, moving the head complete has no effect on runout. alignment possibly, not runout.

Sorry, you're right Richard -- alignment, not runout. I was describing the analog of grinding the spindle taper in situ to minimize runout with Clausing boring the spindle sleeve in situ to minimize alignment errors.

lazlo
11-19-2010, 02:44 PM
Perhaps the OP wants to use the lathe [ heavens above ] not polish it or take pictures of it.

The above gives me the idea that things can be done if it's possible to get arses un-welded from armchairs.

So you're saying the OP should just use the lathe with "5 - 8 thou" wear on the bed? :rolleyes:

John Stevenson
11-19-2010, 02:56 PM
So you're saying the OP should just use the lathe with "5 - 8 thou" wear on the bed? :rolleyes:
No I'm saying why not try it.

With careful work and setting up chances are he can get this to a couple of thou just by grinding, that 2 1/2 to 4 times better than he has at the moment.
Which is probably what most people have on their S/H machines but they just don't know it.

Look at on site machining, they roll up with a van, packet of sandwiches, flask and a load of machine bits like a mecanno set that they assemble round whatever it is they have to machine like large valve housing, bearing base etc.

Once the flask is empty and the sandwiches are gone they pack up and go back to base, job done.
Hefty bill in the post and this goes on every day in virtually every country of the world.

TexasTurnado
11-19-2010, 03:53 PM
then wouldn't the alginment be absolutely constrained by the V way to the V in the headstock :confused:


Not all lathes have the headstock constrained by the V way: the Colchester I am rebuilding uses a clever pair of cams on the rear of the hs in conjunction with a locating dowel at the front to allow adjustment in the horizontal plane (the small block between the ways).

http://i288.photobucket.com/albums/ll168/TexasTurnado/P5040088.jpg

That said, the flat ways still have to be scraped to adjust the hs alignment in the vertical plane.

TexasTurnado
11-19-2010, 04:17 PM
Here are a couple of pix before grinding:

http://i288.photobucket.com/albums/ll168/TexasTurnado/P2250017.jpg

http://i288.photobucket.com/albums/ll168/TexasTurnado/P3310056.jpg

And here is a pic after grinding:

http://i288.photobucket.com/albums/ll168/TexasTurnado/P5070032.jpg

It came back with a layer of grundge from the coolant the grinders used that was stubborn to remove. On the bed ways were numbers showing how much had been removed from each one - they did this in a manner so the ways would be level with each other, just lower.

In answer to the question earlier about alignment on the grinding table, the top of the each V is a reference surface that is unworn (or should be), and this is used for vertical alignment. Other unworn surfaces are used to establish horizontal alignment.

The above applies if the bed is not warped - in that case the alignment is more complicated and relies on the experience of the person doing the setup.

lazlo
11-19-2010, 04:21 PM
Here are a couple of pix before grinding:

John, post the picture where Commerce has the bed wear marked with a Sharpie.

By the way, that's my air compressor in the background of the last picture, you bastard! :D

TexasTurnado
11-19-2010, 04:32 PM
The 300 inch Waldrich Coburg (the yellow post at back is a jib crane for loading and unloading work):

http://i288.photobucket.com/albums/ll168/TexasTurnado/P5070022.jpg

Some waiting work:

http://i288.photobucket.com/albums/ll168/TexasTurnado/P5070023.jpg

Riding the 300 inch Blanchard (note the "little" cylindrical square at the left edge of the pic):

http://i288.photobucket.com/albums/ll168/TexasTurnado/P5070025.jpg

Needless to say, I was very impressed with Commerce Grinding :) The machines shown are only two of many, many there. Their complex occupies almost a whole block on which there are several buildings!

TexasTurnado
11-19-2010, 04:35 PM
John, post the picture where Commerce has the bed wear marked with a Sharpie.

By the way, that's my air compressor in the background of the last picture, you bastard! :D

Hey now, you should have came and got it before the thieves did! :D It sat there for at least three or four months.....

John

TexasTurnado
11-19-2010, 04:41 PM
John, post the picture where Commerce has the bed wear marked with a Sharpie.

You mean this one? This is how many thou was removed from each surface.

http://i288.photobucket.com/albums/ll168/TexasTurnado/P5070033.jpg

The Artful Bodger
11-19-2010, 04:47 PM
Now when I read that you had a "cunning plan" I thought you were going to say something like, ummm........

"I am going to sprinkle diamond dust over a good portion of the bed then I am going to make a concrete cast of that area, when I lift it off I will have a nice tool which I can use to finish the worn areas that I build up with...."

small.planes
11-19-2010, 05:28 PM
A CVA is not a cheap machine by any stretch. The idea of throwing it away and replacing it with anything comparable for less money than fixing it is like
Baldricks plan to fix a ceiling:

Let us not forget you tried to solve the problem of your mother's low ceiling by cutting off her head.

I have one, and its most likely worn beyond all possible redemption... I have no idea. I havent measured it.
I make things with it.
I do know that the bedway is worn some, it has different levels of 'polish' in the surface finish.
However, like the OP I am some way from doing anything about it.

Having thought about it for a little while I think that using the underside of the main saddle ways to guide a grinder would work fine, if you used some method of springing it upwards.
The under saddle gibs on a CVA are, like a 10EE, roller bearings.
As such wear to the underside is minimal, and when new they must be parrallel to the topside, or the saddle gibs wouldnt work...
Something like a rigid roller fixing, with a sprung upper roller. Join each side together with an inverted U, make 2 of them and join them front to back.
Attach grinder to top of U and have at it...

Dave

.RC.
11-19-2010, 05:29 PM
The 300 inch Waldrich Coburg (the yellow post at back is a jib crane for loading and unloading work):

Nice pictures... I have seen and heard of other slideway grinders where the work is stationary and the grinding head moves..

Picture of one type here http://www.cpe.net.au/images/current/services/reco/reco1.jpg

4GSR
11-19-2010, 06:26 PM
Nice pictures... I have seen and heard of other slideway grinders where the work is stationary and the grinding head moves..

Picture of one type here http://www.cpe.net.au/images/current/services/reco/reco1.jpg

Now I've seen it all!!!

oldtiffie
11-19-2010, 06:54 PM
At this advanced stage at which just about every one but the OP is discussing just about everything but the OP's posts and his machine, and given that in this 8-page 72-post (to date) thread in which the OP posted at posts:

#1:
http://bbs.homeshopmachinist.net/showpost.php?p=610800&postcount=1

#25:
http://bbs.homeshopmachinist.net/showpost.php?p=610885&postcount=25

and (so far as I can see) not a word since.

I'd be interested to see what the OP thinks and/or intends thus far.

form_change
11-19-2010, 08:48 PM
Time is a bit precious at the moment as we have 'company coming', but I stole some time and did some (rough) measurements with a micrometer. These were done in metric and converted to the nearest thou -
In 4" jumps moving along the front parallel way (front side of the tail stock) from the head stock, deviation (wear) in thou. 0,0,4,6,5,2,1,0,1,0,0. Rear parallel way (far edge of the carriage) 2,2,3,2,1,1,0,0,0,1,0,0.
I didn't have the time to properly measure the front V way, but when I set up the bearings the manual said there should be a 1.5 thou gap between the roller and the underside of the way. Setting the roller when the carriage was at the tailstock end, I had around 5 to 8 thou when in the usual working zone on the carriage.
I tried levering the tailstock quill when clamped to the bed. With moderate force close in I got 2 thou movement, with the quill 4" out I got 4 thou movement. Sliding the centres together, there is a vertical mismatch of around 1mm (40 thou). Extending the quill and the mismatch is worse.
From this I conclude that the front tailstock way has worn, as has the front carriage way. In addition, the tailstock is around 1mm down.
Scraping takes of 1/10th's, so for this sort of wear grinding is really the only way to go, it's just a question of how and where. I'll investigate the local leads provided but I spoke to a machine tool re-fitter and he said with the bed on no one in Adelaide had a machine big enough to do a proper job.

Michael

Mcgyver
11-19-2010, 09:41 PM
Not all lathes have the headstock constrained by the V way: .

I know that, my DSG is another example....I was responding to lazlo's post showing the pic of the V way under the headstock....I should have quoted then it would have been clearer :)

oldtiffie
11-19-2010, 09:50 PM
Thanks Micheal.

First of all, for those not in Australia, and as there are shops to do the work in the OP's home city of Adelaide, it is probable that the nearest cities with those facilities will be Ballarat and Melbourne in Victoria (~500 miles/800 Km) or Sydney or Newcastle in New South Wales (1,600 miles/2,000Km). So the transport costs may be high. I had a 800 pound shaper transported from Sydney recently and it cost ~ US$70 "depot-to-depot" plus US$120 for a tilt-tray truck and a fork lift with the shaper from depot to my home. The Sydney to Melbourne route is very busy and there is plenty of spare capacity at times.

I have checked the figures you gave (I will work in "thous" too on this occasion. The way wear starting at the head-stock and moving right in 4" increments are:

Front: 0,0,4,6,5,2,1,0,1,0,0.
Back:. 2,2,3,2,1,1,0,0,0,1,0,0.

The biggest deviation over any 12" or 8" or 4" on the front is 0.006"

The biggest deviation over any 12" or 8" or 4" on the rear is 0.001"

The difference between front and rear at each carriage position is:

Front:.............. 0,0,4,6,5,2,1,0,1,0,0.
Back:............... 2,2,3,2,1,1,0,0,0,1,0,0.
Difference:....... 2,2,1,4,4,1,1,0,1,1,0
Mean/average:. 1,1,3,4,3,1,1,0,0,0,0

The mean/average is important as it averages out the wear at each position and will be pretty close to what the tool rises and falls as the tool is about mid-way between the front and rear ways.

If, say the tool rose or fell 0.006" from say centre height over 8" it would increase the turned radius of a 2.000" diameter work piece to 1.00002" and its diameter to 2.00004".

If the toll were set 0.003" "off" such that it was say half above and half below the centre height over the saddle travel, the tool would 0.003" maximum from centre height, in which case the 1" radius of the same 2" diameter work-piece would only increase to +/-1.0000004" and the 2" diameter would be 2.0000009".

The difference will increase approximately linearly as the diameter decreases.

This only refers to vertical wear on the ways. It does not take account of unbalance/unequal lateral wear on the ways or any similar wear on the ways under the saddle.

If you are having significant "sizing" problems with your lathe, I'd suggest that you look further and else-where on the lathe other than the ways to at least see what the real errors and effects really are and what if anything needs to be or can be done to rectify it/them.

I am not and intend not to advise or tell you what to do as that is wholly and solely your right and prerogative.

Best of luck.

beckley23
11-19-2010, 10:25 PM
Is there a reason you can't separate the bed and base, and then send the bed, only, off for grinding? My 30" centers EE bed weighs approx 600 LBS.
Harry

TexasTurnado
11-19-2010, 11:44 PM
As the title says, the wear on the bed ways is only the beginning of the errors on a well used machine. In the case of my Colchester, the saddle was worn more at the hs side than at the ts side, and it was worn more on the the side closest to the operator than at the back way - so it was twisted in both planes. I solved both these problems by machining and adding Turcite.

Then the ts was worn more at the hs side, so the ram was drooping - besides the fact the ram was worn in its bore in the vertical direction on both the ram and in its bore. The ts was too low after grinding, but the way surfaces of the ts cannot be built up with Turcite or Moglice, as these materials do not allow the ts to be clamped tightly enough to the ways to resist sliding. I personaly do not like shims, so I elected to make a complete new ts base from a piece of Durabar. I machined it as closely as I dared, and then scraped to final fit - after having the bore ground round and making a new ram from 4140HT.

The point is, the farther you dig into the problems of a heavily used machine, the more problem areas you will find - it's much like the layers of an onion.....:D

form_change
11-20-2010, 12:02 AM
I don't particularly want to separate the bed from the base for three reasons -
Firstly because once it's off I don't know how the casting is going to move;
Secondly because I don't know whether the clamping to the grinder will twist it;
Lastly because getting it back on may put additional distortions into it.
Other than that I'm quite open to the idea...

Seriously it might come to that but I can imagine distortion easily equal to what I have occurring if things did not go well so it's really a last resort.

I could probably live with the bed wear (although it offends my sense of 'rightness') but it's darn annoying not being able to use the tailstock for drilling a hole. It's either bell mouthed or risks breaking a drill. Several people have suggested shimming the TS, but some of that 40 thou is due to way wear so how much to shim? I also wonder whether it is worth spending a lot of time getting the TS back in shape knowing it is on a worn bed.

Further thoughts - the headstock is mounted on the (continued) TS ways. Any removal of material will lower both the same amount. CVA's have serial numbers stamped all over them (although I can't find one on the TS). I do have a few parts that have different serial numbers (and the contactors are certainly not original) so it's also possible that I have a TS from a different machine to further complicate things.

Michael

Michael

J Tiers
11-20-2010, 12:09 AM
So you're saying the OP should just use the lathe with "5 - 8 thou" wear on the bed? :rolleyes:

Might as well give it a shot......

Unless there are noticeable problems, why borrow expensive trouble?

I have to assume the OP has actually used it, has obvious, troublesome, genuine, issues about performance, and wants to improve it. Just because it looks ugly isn't a reason to go ape 'fixing" it.

Just think about all the folks who "refurbish" old Atlas etc...... carefully disassemble, clean, paint, and re-assemble, carefully replacing the decals and putting on repro brass tags, etc, etc. And they seem quite happy with their "now new" machine, despite teh fact that they have not altered the actual performance one iota.

I know about most of the problems my lathe has, I either deal with them, or fix them. I need to at some point scrape teh crosslide ways, since the slide gets a little tighter as it moves, and loose enough to work there is too loose elsewhere.

I am not getting nutty about it , since I still can get the work out as I want it.

TexasTurnado
11-20-2010, 01:06 AM
I don't particularly want to separate the bed from the base for three reasons -
Firstly because once it's off I don't know how the casting is going to move;
Secondly because I don't know whether the clamping to the grinder will twist it;
Lastly because getting it back on may put additional distortions into it.
Other than that I'm quite open to the idea...

Seriously it might come to that but I can imagine distortion easily equal to what I have occurring if things did not go well so it's really a last resort.



Just my opinion, but I think any distortions generated by removing and replacing the bed will be second or third order effects compared to the wear present. And the grinders are not going to distort the casting if they are qualified to do bed grinding - they know if they distort the casting with their clamps it will spring back after it is removed from their machine, ruining their fine work....

As Lazlo indicated, I also have a SAG 12 I am rebuilding, and it has the hs integral with the base, but the bed is removable. I did not hesitate to remove it to have it ground at Commerce after my experience with the Colchester. I think you are being overly cautious.....

PeteF
11-20-2010, 02:00 AM
Michael, I'm not sure you've been given good information from your friend regarding grinding here in Adelaide (where I am now as I type). At the end of the day, something the size of a 10EE isn't THAT long so I would definitely be chasing those contacts and getting the information first hand.

The other thing is, are you sure the tailstock you have is actually originally from that lathe and hasn't been swapped from another? As you're aware, each is scraped in to suit its own parent machine and sometimes they get mixed up if there's more than one machine when they're sold off. I was in that situation myself and had precisely the same symptoms as you, so know how frustrating it is. I shimmed mine up and it's now quite good. It still droops very slightly so I could either play with the shims some more or scrape it to perfectly level, but to be honest it would simply be for the sake of it as I have never found that slight inaccuracy to be anything other than an annoyance on paper.

Pete

darryl
11-20-2010, 04:41 AM
Going back to Michaels original proposal, I'm intrigued by the idea of creating a linear slideway framework to mount a tp grinder on. I'm not advocating this idea, as I agree the best way to get the job done is by using a commercial bed grinding service.

However, the idea has been going around in my mind the last while. How could it be done-

Chances are there is little wear very near the HS, and with luck a similar situation is found at the extreme right end of the bed. If not, do not read this any further.

Ok- a piece of certified straight rod is found and three collars are machined to fit it very closely. These should then be split at some point so they can be closed up around the rod- a hose clamp would be good enough for this job. A stub which is a tad larger than the rod would be mounted and turned to give a method of holding it in the spindle bore, and is subsequently turned to the exact OD of the rod. The stub is not disturbed from this point on until the entire job is done. The idea is to create a mounting point for the rod which is concentric and as close to the HS as possible. One of the collars straddles this stub and the rod, and as the clamp is tightened, the rod becomes totally concentric with the stub. If the collar is mounted squarely, the rod is precisely held to the spindle axis. But there is much to do before the rod can be mounted.

A piece of plate is machined to fit the way surfaces and a means created to hold it there squarely and upright. It is brought up to the stub and secured, and a mark is drawn on the plate around the stub. The plate needs this hole cut out, slightly larger than the rod. Centering the hole is not critical, only that the hole doesn't interfere with the rod as it passes through on axis. One of the collars is lightly snugged onto the stub, the plate brought up to it, everything squared, then the collar is affixed to the plate in that exact placement. I would have mounting holes predrilled in the plate, then marked and drilled in the collar, then the collar epoxied in place, with epoxy only on the bottom half, then the lower securing bolts installed and tightened. This assembly is then removed off the stub carefully (it will be quite snug) and
set aside.

In order for the grinder head to traverse enough distance to enable the complete length of the bed to be ground, minus some at the HS end, the rod will have to be longer than the bed. With a rod of suitable length on hand, carefully slide the plate assembly onto it and into a position where the rod can abut the stub in the spindle and the plate can mount to the bed at the extreme right. One collar needs to be in place at the stub, while the third one is not used yet. The rod is now mounted, the plate squared, and the collar straddling the stub and the rod is squared and tightened. The plate is tightened to the bed, and that collar is resnugged with its hose clamp.

The end result of all this is a mounted guideway that is parallel to the bed. God help us all if the HS is out of alignment with the bed- Oh, and before the rod is mounted, the carriage and all is removed from the bed.

Some rod sticks out past the end of the bed. The third collar is placed onto it. This is where a way must be found to secure the rod in this position relative to the end of the bed. Once a vertical plate has been rigidly fixed into position and squared to the end of the rod, the collar is tightened up to it and snugged up with the hose clamp. The goal obviously is to be able to slide the first plate assembly off the bed without the rod moving one iota. The length of the rod must allow the first plate assembly to hang loose at the far right and not interfere with the full motion of the grinder module. There's probably going to be some drilling, tapping, and welding going on to create this outboard plate mounting structure. However this is done must not distort the bed in any way. You might want to put some 'presag' downward pressure on this outboard mounting before tightening the collar to it, just to mimic the sag that would be introduced by the weight of that end of the rod.

So- now we have a single guide rod placed solidly on axis, and nothing to keep the grinder module from swinging around on it. It may be possible to use the unworn underside of the rear way as a control surface for the grinder module- but make sure the control arm doesn't run off it before the grinder had made the full pass.

Not an easy or quick task overall- but possible, and I believe it's possible to do a good job of the grinding. And of course, so far we haven't even touched on the making of the grinder module.

Ok- I have my bulletproof vest on-

Richard Wilson
11-20-2010, 06:23 AM
So you're saying the OP should just use the lathe with "5 - 8 thou" wear on the bed? :rolleyes:
What the OP hasn't said (I think) is what results the lathe gives in use, which surely is the important thing. If it can to do his work (whatever that is) to within his required levels of accuracy ( I'm a +/-.001" on a good day man, some of you think thats blacksmith stuff.) then stop worrying. Sure it sounds like he needs to shim the tailstock, but thats not difficult or expensive.
I've got an old clunker that only gets used for flywheels and the like now, because its got a gap bed and my more 'modern' lathe (only 60 years old) hasn't, but I used to use it for everything including crankshafts and its so worn I dare not measure it, the results would scare me to death, but with a bit of humouring it did well. Not everyone needs +/-.0001". If the OP is doing commercial work for third parties, then yes, if he's only working for himself, then possibly not. It sounds like its an awful lot of trouble and cost to get the bed ground, and I would ask myself if the difference in the end product was worth all that trouble and expense. In my youth in the 1960s I worked in sub contract machine shops in the West Midlands where the most modern machines still had 'War Finish' stencilled on the beds. What distinguished the skilled men from the rest (i.e me) was their knowledge of how to compensate for their machines failings and still get results that passed the customers inspection processes.
This site is wonderful, but if it had been around when I was starting my home workshop in 1965 with a well worn pre war Myford, there's just a chance it might have convinced me that without much more modern machinery and equipment, I was wasting my time and money. As it was, I didn't know any better, so just went ahead anyway and started building engines, which I'm still doing 50 years later, and still get a great deal of enjoyment and satisfaction from it.

Richard

.RC.
11-20-2010, 07:24 AM
The plan is to make up a frame that will bolt to some pretapped holes in the side of the lathe bed and using some linear rail, make up a carriage that I can attach a tool post grinder to. I'll use that to take out the major imperfections and then use a carbide scraper and straight edge to do the last bit.


Getting back to the original idea, I think what Beckley did to his 10EE is probably the best way to go... Scrape the flat ways and grind/scrape the V's with a sled type device..

You can probably either try to get a Biax from overseas (they do not seem to ever come up here) and use that or make your own mechanical scraper out of a reciprocating saw like this one here http://www.practicalmachinist.com/vb/general/power-scraping-anyone-tried-convert-makita-hk0500-metal-161099/

Also regarding the tailstock, Forrest did a great writeup here on reconditioning a tailstock barrel. His is post #9 http://www.practicalmachinist.com/vb/general/fit-t-s-ram-casting-158423/

Between Practical Machinist and this site there is a huge amount of reference material... Combine that with Connelly's book and google and the sky is the limit on what you can learn...

.RC.
11-20-2010, 07:50 AM
Not all lathes have the headstock constrained by the V way: the Colchester I am rebuilding uses a clever pair of cams on the rear of the hs in conjunction with a locating dowel at the front to allow adjustment in the horizontal plane (the small block between the ways).

Pretty much all British lathes and lathes based on British designs are like that.. My AU made purcell http://www.lathes.co.uk/purcell/page3.html is similar, This bed is very very well worn as well (it had a hydraulic tracer fitted and the ways are very soft cast iron), but amazingly it will hold 0.02mm over short distances like 50mm

http://img.photobucket.com/albums/v606/OzRinger/purcell%20lathe/purcelllatheathome079.jpg

luthor
11-20-2010, 08:32 AM
Ok- I have my bulletproof vest on-

Darryl, what diameter do you propose this "certified straight rod" would be to provide sufficient ridgidity over the 6+ foot span? 6 inch diameter maybe?

lazlo
11-20-2010, 10:42 AM
Getting back to the original idea, I think what Beckley did to his 10EE is probably the best way to go... Scrape the flat ways and grind/scrape the V's with a sled type device..

Harry is a master machine rebuilder - the outstanding "Rebuilding a Monarch Lathe" in the mid 90's Home Shop Machinist is his. I've seen at least 4 major machine rebuilds he's done.

The 10EE (and the CVA) have hard beds. Even with a power scraper, that's sheer masochism, even for someone like Harry.

gnm109
11-20-2010, 11:39 AM
Harry is a master machine rebuilder - the outstanding "Rebuilding a Monarch Lathe" in the mid 90's Home Shop Machinist is his. I've seen at least 4 major machine rebuilds he's done.

The 10EE (and the CVA) have hard beds. Even with a power scraper, that's sheer masochism, even for someone like Harry.


Beckley (Harry) certainly is good at rebuilding machines. I read every word of his posts over on PM and some of it was incredible. It made me all the happier that I bought a new lathe back in 1993 when I was looking for one. Although it is Chinese, it was straight with induction-hardened ways and it was a good start for someone who doesn't have the equipment nor the ability to scrape in a lathe.

I can't even remember how many used, clapped-out, boogered up, knackered, totally worn out junk lathes that I looked at before I finally gave up in my second year of searching. When you can actually see the wear in front of the chuck without even measuring it, it's time to move along.

Good luck to the OP here. Frankly, I don't envy him the job. It's especially difficult when you are in an area like OZ that has great distances. Like OZ, Sacramento where I am, has no machine shops of which I'm aware for that sort of machine rebuilding. If I needed that sort of work, I'd have to ship the item to Los Angeles. That's 400 miles each way, almost as bad as the distances he has been quoting.

Good luck! :)

S_J_H
11-20-2010, 12:01 PM
I have built a couple machines from scratch using linear ways. This was my small bench lathe-
http://i109.photobucket.com/albums/n48/S_J_H/cnc%20bench%20lathe/cnclathe012.jpg

Getting the 2 slideways properly aligned was a lot of very tedious work.
I managed to get them within .0002" over the length of travel which I think was around 12". It is hair pulling work when working with tenths over some distance.
I used a surface plate that was positioned vertically as a reference amongst other methods.

A 6ft span is going to be very difficult to get right. Not impossible, but very difficult.

My SB bed is pretty heavily worn -
http://i109.photobucket.com/albums/n48/S_J_H/SouthBendLathe006-1.jpg
The wear ridge is about 015"-.020" and I have toyed with a very similar idea, using a sled arrangement to plane it. But the carriage averages out the bed wear and the lathe will still cut within .0004" over 6" which is good enough for me.
If you decide to tackle this job please take a lot of pics!
Steve

TexasTurnado
11-20-2010, 12:45 PM
He needs to decide what he will be satisfied with and how much he is willing to spend in money and time. In my dreams, I can imagine it might be possible to regrind the ways using a Dremel and spotting techniques as in scraping (in combination with belt sander or similar), and with unbelievable patience. :D But I would also guess 99 out of 100 people would give up long before the job was done!

In my case, I found a nice almost unused Biax on ebay, complete with a set of carbide scrapers. Having heard the ways were hardened on the Colchester, I decided to give it a try with the Biax - it took less than 5 minutes to convince me that was not the way the job was going to get done! I have done some hand scraping before, so the techniques were already known.

The ways were so hard, the cutter preferred to bounce off and left a very rough surface. I will admit, that with a lot of practice, it would have gotten better, but I could not imagine being able to scrape the V ways to the accuracy needed with them being so hard - so I opted for the grinding route.

My goal was to have a lathe, that when finished, would be as good or better that when it was originally built. Up to this point, I have done all of my home activities on an disdained Craftsman Atlas 12 x 24 lathe. It was not especially worn when I got it from my father (he was retired in Florida and got it from a widow of a retired machinist), but it was a learning experience to compensate for its shortcomings.

At some point, I tired of not being able to cut in reverse, and the small bore of the spindle, so I found a spindle from a 5914 and fit it to the Atlas:

http://i288.photobucket.com/albums/ll168/TexasTurnado/Photo24-P1010112a.jpg

I also made a new ts and cross slide:

http://i288.photobucket.com/albums/ll168/TexasTurnado/Photo25-P1010114.jpg

This setup was a vast improvement over the stock Atlas, but still suffered from the poor rigidity of the basic design - but I learned to compensate for that and have done all my recent lathe work on it.

Now I am ready for a good lathe and that was my goal in rebuilding the Colchester - my point is, the OP needs to really decide what he wants and then persue it....

RussZHC
11-20-2010, 12:56 PM
Texas T:
PM sent.

rkepler
11-20-2010, 01:02 PM
Getting back to the original idea, I think what Beckley did to his 10EE is probably the best way to go... Scrape the flat ways and grind/scrape the V's with a sled type device..

The only problem with that is all of the other tooling that you need. Let's make a list:

1) Power scraper. You might be lucky and find one for $400. maybe.

2) Straight edge as long as the longest area (preferably a bit more, really) ($200 If You're Lucky)

3) Surface plate capable of proving the straight edge ($300 IYL)

4) Precision level ($150 IYL)

Marking crap like dyes, grinding stuff (diamond if you're using carbide), etc.

If you decide to scrape the bed you're going to be making all sorts of jigs to check that things are parallel. Flat is the *easy* part in a lot of ways - slap some marking gunk on the straight edge, rub a little on the surface being scraped, scrape off the markings. Rinse, lathe, repeat. But what do you do when the surface has to be parallel to another? Are you ready to machine and scrape in all the check blocks? Do you have the indicators and such to compare surfaces?

Read the lathe portion of Machine Tool Reconditioning a couple of times, when you think you understand it read it again for how to fix a twist, the reconditioning of a tailstock, etc. I learn something new every time I reread it.

Call it $1000 If You're Lucky, more like $1500 is you're in a hurry.

If all you're doing is the refit and not doing the bed all you're going to need is a little Anderson scraper and the "marking crap" and grinder. Probably $1000 less. That's just the cost - the difference in effort is a lot more.

All in all starting with a precision ground bed lets you drop a lot of the stuff that you need to scrape the bed. The bed becomes the master for most of the scraping operations, simplifying almost everything. It's still a lot of work but likely 3x easier than starting out scraping the bed.

Mcgyver
11-20-2010, 03:44 PM
The only problem with that is all of the other tooling that you need. Let's make a list:

1) Power scraper. You might be lucky and find one for $400. maybe.


take note of the the IYL part; price out a 60" staight edge new; they're thousands.....then add the years of gym membership to be able to properly manipulate it. I've got a 60" and can carry it around, but the care required to place and spot with it isn't really a one man job

When someone says they've scraped hardened ways they're either full of it, or have a big S on his chest....(if you're read Harry's excellent threads he is definitly not full of it, he must wears the S)...... I didn't try the power scraper but seeing how a perfectly lapped carbide scraper just bounces off, well, its a daunting task.


Darryl, what diameter do you propose this "certified straight rod" would be to provide sufficient ridgidity over the 6+ foot span? 6 inch diameter maybe?

it always comes back to the same problem, you can only create flat from flat (yeah i know about origination, but that's not applicable here). Price out a cylinder long enough to carry a grinder the length of the ways, large enough its not going to sage and perfectly ground over its (6'??) length. Lathe bed grinding will look cheap in comparison

While its being out a couple of thou up and down won't much matter, but it absolutey will if its out in the direction of the compound (X?)....it'll never turn properly in that case. So said cylinder needs to be perfect, and big....big and perfect=mucho dollars

what might be doable is a ground cylinder with a bunch of points along it where it can be tweaked, use an autocollimator to tune it into the perfect shape...then use it at a slide. avoids some cost in making the prefect cyinder.....other than armchairiong the idea though, if there was a grinder with 1000 miles thats how i'd go.......or psych myself up to wear the S and scrape it.

TexasTurnado
11-20-2010, 08:04 PM
approach it thusly: Some years back I saw a new lathe bed on ebay - from the description, an optics lab had purchased it to use to slide their mirrors around for laser experiments. In any event, I would procure a lathe bed (or similar), and make sure it was not hardened, so I could scrape it flat if needed. Then I would carefully mount it parallel to the bed to be ground in both planes and use a grinder mounted to that second bed to grind the first one.

This could possibly be cheaper that taking it to a grinding shop (depending on how much you value your time), but almost certainly would not attain the .0001 per foot or the parallelism that large slideway grinders are capable of.

But I echo the comments in the previous post: If there was a capable shop within a 1000 miles, I would personally drive it there and go back to pick it up myself. I'm not sure if the Colchester bed would fit in my Jeep Cherokee without removing the front seat (I used a trailer to make that trip), but the SAG12 bed certainly did. But I would remove the front seat for the trip if necessary, rather than trusting it to a third party shipper. :D

form_change
11-20-2010, 09:22 PM
Nice plan, but the family car is a Mazda 323 (small hatch) and the bed is 6ft long.
The original plan before linear bearings was making up 3x6ft long truss frames say 8" deep with a 1/2" thick mild steel face on each that (because there were 3) could be scraped in to flat. These would then carefully be attached to a sub frame along their neutral axis (no induced stresses), providing the equivalent of another bed alongside the bed to be ground.
I have noted the opinions of those voting for a professional grinding job, and I'll be asking some questions about that but still think the cost could end up being prohibitive. One idea that has appeal from the discussions on this topic is the thought of using the underside of the ways. The back parallel way is in an acceptable condition, so using that and the undersides should (theoretically) provide a good reference surface. If only I had an old lathe bed to experiment on...

Michael

.RC.
11-20-2010, 09:38 PM
Shameless scraping pircture... As I just did it ten minutes ago...took me half an hour to go from milled surface to this...

http://img.photobucket.com/albums/v606/OzRinger/surfacegauge006Custom.jpg

Richard Wilson
11-21-2010, 07:11 AM
[QUOTE=S_J_H]I have built a couple machines from scratch using linear ways. This was my small bench lathe-
http://i109.photobucket.com/albums/n48/S_J_H/cnc%20bench%20lathe/cnclathe012.jpg

[I]My SB bed is pretty heavily worn -
http://i109.photobucket.com/albums/n48/S_J_H/SouthBendLathe006-1.jpg
The wear ridge is about 015"-.020" and I have toyed with a very similar idea, using a sled arrangement to plane it. But the carriage averages out the bed wear and the lathe will still cut within .0004" over 6" which is good enough for me.[/I
Exactly the point I was trying to make. Don't get hung up on measuring wear if the machine still produces results which are acceptable for your sort of work.

Richard

PeteF
11-21-2010, 10:38 PM
Nice plan, but the family car is a Mazda 323 (small hatch) and the bed is 6ft long.
The original plan before linear bearings was making up 3x6ft long truss frames say 8" deep with a 1/2" thick mild steel face on each that (because there were 3) could be scraped in to flat. These would then carefully be attached to a sub frame along their neutral axis (no induced stresses), providing the equivalent of another bed alongside the bed to be ground.
I have noted the opinions of those voting for a professional grinding job, and I'll be asking some questions about that but still think the cost could end up being prohibitive. One idea that has appeal from the discussions on this topic is the thought of using the underside of the ways. The back parallel way is in an acceptable condition, so using that and the undersides should (theoretically) provide a good reference surface. If only I had an old lathe bed to experiment on...

Michael

This is a clone of a 10EE and has a 6 ft long bed?

To give an indication of cost, to grind a Hercus/SB 9 bed is about 300 bucks, throw in another 75 to rent a ute and engine lifter for the day!

Even if you did manage to build a temporary bed around the other one AND managed to get it perfectly straight etc etc with your 6 ft straight edge you have, what were you thinking of using as a grinder? I had to laugh when somebody suggested using a dremel, you may as well try free-handing it with a belt sander!!

.RC.
11-21-2010, 11:05 PM
Is the bed of a 10EE scraped to the base? If so the CVA might be as well so there will be no distortion issues...

form_change
11-22-2010, 04:20 PM
I've been checking out the names suggested for grinding and so far no joy. Hercus can grind up to 900mm long, but I need 1800mm long. They did suggest another company who can do a little over a metre...

While the series 1 lathe could be considered a copy of the 10ee, the series 3 is different enough that it should be considered a separate (although from a common stock) machine to the 10ee. From my point of view, one of the features it has that the 10ee doesn't have is a simple speed change method - most of the posts I read on the PM Monarch forum seem to be about problems people have with the electrics.

The bed being scraped in to the base is one of my concerns - being scraped in it needs to go back exactly where it came from. I can imagine that the beds were ground and scraped for the carriage after attachment (it's what I'd do if I wanted to guarantee what I was producing did not distort). I have removed beds from lathes before but not like this - the CVA base is cast and rests on 3 points on the ground with no attachment screws etc. Simply put, the cast base is a structural part of the lathe. No folded sheet metal here.

PeteF - My plan was to use a tool post grinder, as per the first post in the thread. I haven't done the numbers yet but I can see no problem with a properly constructed truss being rigid enough - it's just a matter of minimizing induced distortions and ensuring enough rigidity. I once made a 3.6m long truss that weighed around 10kg and supported a person in the middle with only a few mm of deflection.

Michael

lazlo
11-22-2010, 04:34 PM
Michael, I have an article from an ancient Model Engineer where a guy jury-rigged a tool post grinder on a track that ran on some unused portion of the bed.
According to the article, it worked great, but I can't remember if he posted measurement after the fact.

How would you dress the wheel for each pass? Especially on a little toolpost grinding wheel, which will wear quickly.

4GSR
11-22-2010, 04:47 PM
Michael,

There's no reason in the world why it won't work..it will. And you will have to some degree a much more accuract lathe than you did before regrinding the bedways. It may not get you .0000001" accuracy, but it will be much better than before. I'm fixing to find out on my 20" Lodge & Shipley lathe in the weeks to come. I'm waiting on some grinding wheels I bought off of eBone.
I don't expect the grinding finish to be that good, but a good oil stone and paint thinner will smooth out to a nice finish!;)

Holding .001" tolerance better than .010"!!!

Ken S.

Robo
11-22-2010, 06:29 PM
Proceed sir cause I want to read about it:)

TexasTurnado
11-22-2010, 10:35 PM
I had to laugh when somebody suggested using a dremel, you may as well try free-handing it with a belt sander!!


I think you missed the point of the post: I was suggesting roughing it in with a belt sander (or equivalent), then spotting it with a st edge and using a Dremel to grind down the high spots (since it may be too hard to scrape), removing only a small amout each time.... Repeating this process many times, as in conventional scraping, should result in a reasonably flat surface in materials too hard to scrape. As the surface got flatter, I would expect the ginding tool would want to be softer, such as the rubberized abrasives.

Besides, think of the benefits - the lower areas between the high spots would be natural oil reservoirs.... no need to flake later! :D

TexasTurnado
11-23-2010, 12:13 PM
Here is the challenge: On a bed like the one on the Colchester, there are 8 surfaces about 6 foot long (2 flat ways, 2 Vee ways with a surface on each side, and 2 surfaces on the underside of the outside ways) that need to be ground to precision flatness and aligned with each other in three planes (counting two for the Vee's).

Using the price I paid as a reference ($1000), that averages out to $125 per surface - does anyone really think they can do this at home at less cost? Even it they count their time as $0 per hour? :D

BTW, the going rate at Commerce was $90 per hour for man and machine, so that means they spent a little over 11 hours on the job, a large portion of which was setup time (initial setup, dressing wheels, setup for the different angles, etc).

lazlo
11-23-2010, 12:42 PM
Using the price I paid as a reference ($1000),

the going rate at Commerce was $90 per hour for man and machine, so that means they spent a little over 11 hours on the job, a large portion of which was setup time (initial setup, dressing wheels, setup for the different angles, etc).

John, did you pay roughly the same price for the SAG?

TexasTurnado
11-23-2010, 02:23 PM
John, did you pay roughly the same price for the SAG?


Yes, it was maybe $100 less - I would have to dig up the receipts to quote an exact number.

oldtiffie
11-23-2010, 04:01 PM
I wonder what the OP's thoughts are now as regards feasability, scope of works, time-lines, cost as well as required outcome.

ulav8r
11-23-2010, 07:51 PM
Tiffie, instead of wondering, why don't you just ask him???????????????

Mcgyver
11-23-2010, 08:33 PM
Tiffie, instead of wondering, why don't you just ask him???????????????

lol, he's tied up searching for a "I was wondering" wiki link

oldtiffie
11-23-2010, 08:36 PM
Because some of the items I mentioned are or maybe regarded by the OP as being (more) "personal" than tool/shop-related.

My "wondering" gives the OP the option of not replying where-as my "asking" may seem to imply that I "need to know" - when I really don't.

.RC.
11-23-2010, 10:50 PM
The bed being scraped in to the base is one of my concerns - being scraped in it needs to go back exactly where it came from.

It only has to fit on the scraped area as the whole scraped area is going to be flat.. I can not see removing the bed from the base as an issue...

oldtiffie
11-23-2010, 11:05 PM
Why not just grind the mating faces of the bed and base.

Or why scrape or grind them at all?

The lathe - presumably - is going to have to be re-leveled and tested.

form_change
11-23-2010, 11:12 PM
I managed to get an indicative price for a bed re-grind from the only company I could find in town that has a grinder large enough to do the job.
To take between 5 and 10 thou off 6 surfaces is priced at between $2000 and $3000. (for those in the US, the Oz$ and the US$ are almost the same at the moment so those numbers can be taken as read). The problem is the size of the lathe bed - smaller grinders exist but the big ones are harder to find.
While it would be nice to have the grind done professionally, I certainly can't throw that sort of money around. I want to change the oil valves over the Xmas break so while I'm doing that I'll get the straight edge out, do some further assessment and have a look at the carriage running surfaces. The TS needs aligning and raising up as well to be get rid of some issues with it.
I have not been convinced by anything said so far that grinding at home is not possible (I will acknowledge difficult, exacting, time consuming etc etc) and one thing I would like to do is find a small old lathe bed and experiment a little with it - see what can be done. That won't be for a while. I will document and photograph so that if a success others can see what has been done.
Michael

Mcgyver
11-23-2010, 11:26 PM
Why not just grind the mating faces of the bed and base.

Or why scrape or grind them at all?

The lathe - presumably - is going to have to be re-leveled and tested.

If the lathe is scraped to the base, you don't know that the areas of contact are in the same plane or even parallel planes, only that they are perfect (to the ability to scrape, say a tenth or better) mates. So if you take the lathe bed off, and the surfaces where it mates the base are NOT in the same plane, it will not sit flat when on the grinder table and you may in fact temporarily distort the casting via holding it to the table.

you could, invert the lathe, hold on three spots, shim and grind the bottom of the bed, then grind the top of the base putting both the mating areas of both parts in the same plane. You grind the ways then and take delight in the knowledge that it'll go back together perfectly....but unless you're working with a mismatched base and lathe, why go through all the work? just ship the bed mounted on the base.

I'm sure lots of guys have figured the men in Sidney probably ground or machined one of the surfaces first so that the scraped lathe and base fit is likely close to planer and that just grinding the bed (detached from the base) is fine. And maybe it would be....but.....if you're at all concerned about getting the perfect job done on maybe the nicest lathe there is, it would be FAR less work to send out lathe and base rather than grind/rematch the two surfaces

Keep in mind these lathes do not need levelling. The base rests on the floor on three points.....you just set it on the floor and alignment should be perfect. That underpins, literally, the reason for maintaining the base/bed fit

form_change
11-24-2010, 03:20 AM
I read Mcgyver's post and thought it was a good exposition of some of my concerns and why I don't want to split the bed from the base.
The only additional comments on it I will make are that regardless of whether or not the mating surfaces are co-planar, because of the precise nature of the surfaces having separated they then have to be carefully protected. Unless I build a proper full form crate, I don't know whether that will happen. Even at the grinder's (although you assume normal care will be taken) accidental damage to the surface is possible. It's another worry I can do without.
The other concern is that CI does crack. I've already had one casting on the lathe crack when I removed it from the place it had been sitting for around 50 years. The connection between bed and base is a couple of large studs and nuts. It would be a disaster if loosening a bolt for dis-assembly or worse, tightening when reassembling caused a crack to run across the bed casting. I think I would then own around 1500kg of what is called in the trade "mixed scrap". Even without cracking, castings will move particularly if material is removed. While after 50 years I would expect the assembled castings to have reached an equilibrium condition, un-restraining some parts may allow one or both components move to a new equilibrium.
I guess the short answer is that as soon as the joint is broken the amount of risk exposure increases greatly. Even with the lathe's current wear if I have a choice of splitting off the bed to grind it or living with the errors I'd prefer to live with the errors.

Michael

macona
11-24-2010, 03:30 AM
Why not just grind the mating faces of the bed and base.

Or why scrape or grind them at all?

The lathe - presumably - is going to have to be re-leveled and tested.


If it is truly built like a monarch the beds and bases are bedded together and then ground as a whole unit. The base and bed become one, for what its worth and they are not intended to ever come apart. This is why a 10EE does not have to be leveled. In fact, the lathe is only on the ground in three points.

oldtiffie
11-24-2010, 05:01 AM
If it is truly built like a monarch the beds and bases are bedded together and then ground as a whole unit. The base and bed become one, for what its worth and they are not intended to ever come apart. This is why a 10EE does not have to be leveled. In fact, the lathe is only on the ground in three points.

OK. One unit it is and seems intended to remain as such.

I picked up earlier that the lathe is on a three-point/leg "tripod" support and suspension system which like most tripods is self-leveling on the shop floor/slab - ie it will not "rock" as a 4 or more leg/support system may.

When I mentioned leveling I meant in the sense that a surveyor's level or theodolite tribrach/base is leveled - ie in the true horizontal plane - using three adjusting screws. That system will adjust but not impart any "twisting" or distortioning stress on the lathe/level/theodolite.

Also, so far as I can see, the OP is not intending to - or is intending to not - grind the underside of the carriage, the cross-slide or the top slide or the tail-stock.

If that's so, I will make no further comment on it as the matter is decided by the OP as it is his lathe and it is his prerogative.

.RC.
11-24-2010, 06:40 AM
If it is truly built like a monarch the beds and bases are bedded together and then ground as a whole unit. The base and bed become one, for what its worth and they are not intended to ever come apart. This is why a 10EE does not have to be leveled. In fact, the lathe is only on the ground in three points.

I thought I saw a picture once of a Monarch sales catalogue of a whole line of 10EE beds on a Thompson grinder being ground..

malbenbut
11-24-2010, 10:22 AM
Has anyone any pictures of a portable grinding gantry for grinding lathe beds?
MBB

rkepler
11-24-2010, 10:45 AM
If it is truly built like a monarch the beds and bases are bedded together and then ground as a whole unit. The base and bed become one, for what its worth and they are not intended to ever come apart. This is why a 10EE does not have to be leveled. In fact, the lathe is only on the ground in three points.

So far as I know the beds were machined, hardened and then ground with the 'feet' down, then the bed was mated to a base with the base being scraped to match the bed's feet. The base on mine certainly was scraped to the bed - there's 4 bolts holding the bed down from inside the base through some fairly small contact patches, somewhat visible there:

http://www.kepler-eng.com/images/10ee_base_painted.jpg

The base is *very* rigid and unlikely to move on the 3 point mount, so if the bed is mounted to the base without adding strain to the bed it'll be in good shape.

TexasTurnado
11-24-2010, 03:19 PM
I thought I saw a picture once of a Monarch sales catalogue of a whole line of 10EE beds on a Thompson grinder being ground..

I suspect that is indeed the case, as the hs would be in the way of the grinder on lathes with an integral hs - like my SAG12. That's why I was not worried about removing its bed and sending it out to be ground.

On lathes like the SAG12, the entire bed is scraped in to match the hs, instead of the more conventional method. Scraping is only necessary to adjust the vertical alignment, as there is a pin at the front of the bed and two adjustment setscrews at the rear to align it in the horizontal plane.

http://i288.photobucket.com/albums/ll168/TexasTurnado/P7210051.jpg

http://i288.photobucket.com/albums/ll168/TexasTurnado/P8020054.jpg

In the pix, you can see the studs for alignment on the base and the holes for the setscrews on the rear bed mounting flange.

BTW, removing the bed makes it one hell of a lot easier to prepare for and paint the lathe! :D

rkepler
11-24-2010, 03:30 PM
BTW, removing the bed makes it one hell of a lot easier to prepare for and paint the lathe! :D

I don't think I would have painted everything unless I'd removed the bed for grinding. It's a real PITA otherwise. Nice job on your paint, I like to call mine a "10 foot paint job" as that's the best distance from which to view it.

Machtool
11-24-2010, 07:39 PM
I thought I saw a picture once of a Monarch sales catalogue of a whole line of 10EE beds on a Thompson grinder being ground..
Richard

I was just looking at this a few days ago.

Click on the right hand thumb nail pic in this link.

http://www.machinetools.com/us/listings/view/fulltontech-fg200 (http://www.machinetools.com/us/listings/view/fulltontech-fg200)

That looks to me like 3, 4 to 5 metre long slant bed lathe bases sitting on a 20 metre table. Ex Dalian China. Will that fit in your shed?

Regards Phil.

macona
11-24-2010, 07:54 PM
I thought I saw a picture once of a Monarch sales catalogue of a whole line of 10EE beds on a Thompson grinder being ground..


Yep, you're right. I could have sworn I read that they were ground on their bases.

Here's the post with the pic.

http://www.practicalmachinist.com/vb/monarch-lathes/how-monarch-ground-10ee-beds-image-171613/

TexasTurnado
11-24-2010, 09:39 PM
If the lathe is scraped to the base, you don't know that the areas of contact are in the same plane or even parallel planes, only that they are perfect (to the ability to scrape, say a tenth or better) mates. So if you take the lathe bed off, and the surfaces where it mates the base are NOT in the same plane, it will not sit flat when on the grinder table and you may in fact temporarily distort the casting via holding it to the table.

I do not agree...:) When the lathe was made, either the bed or the base was ground (or scraped flat with proper tools), and the mating part scraped to match - at least on quality machines.

That said, I am not nearly as optimistic as many here apparently are, that either the base or the bed is now in the same condition, ie, mating surfaces are still in the same plane. It is pretty well known that cast iron "seasons" and changes as it ages - so why assume the bed and or base is as it was when it left the factory?

If you leave the bed and base together, and they are warped, then indeed, you had better not remove them for any reason if you recondition them that way. :D

It seems quite possible, and indeed probable, that these surfaces several feet apart, are NOT now coplanar. I intend to investigate this at reassembly, and scrape to correct (while also bringing the ways into alignment with the spindle axis.

Also, I think it is shortsighted to think the grinder is going to simply clamp the bed to the grinding table flat on each surface and "have at it"! Not only is time spent carefully mounting the bed to have the ways parallel to the motion of the wheel, but care is given in mounting and shimming to not induce any new stress in the bed. Idealy, if the clamping is right, one clamp at a time can be loosened, and the alignment to the grinding head will not change. This is one reason, the time spent actually grinding is much less the time required to do the job correctly.....

I watched the guy for a while at Commerce Grinding (setting up one of the beds before mine), and he made many trips around the bed adjusting the clamps (particularly where they were located), and running the bed back and forth with indicators attached to the grinding head to get it right before ever turning the wheel on to take a trial cut.

For my SAG12, I will check the alignment of these surfaces with my 6 ft camelback, a Starrett 199, and a small surface plate (as I don't believe my 36 x 48 surface plate is long enough, even on the diagonal). The camelback will indicate if the two surfaces are aligned with each other, the surface plate will tell if they are flat, and the master level will tell me if they are both level with each other.

Then I will probably sit the bed on the base and do the "three papers" test around the perimeter of each mounting flange - this should give an idea how well the bed and base are aligned with each other. Then I will need to check how well the axis of the spindle is aligned to bed ways. This may require a custom slide or I may be able to use the ts base to slide along the ways - I haven't gotten that far yet.....:)

All this wasn't necessary for the Colchester - the plinths at either end are independent of each other and have adjusting screws at the floor to level the bed. :D

PeteF
11-24-2010, 09:43 PM
I'll get the straight edge out, do some further assessment and have a look at the carriage running surfaces. The TS needs aligning and raising up as well to be get rid of some issues with it.
I have not been convinced by anything said so far that grinding at home is not possible (I will acknowledge difficult, exacting, time consuming etc etc) and one thing I would like to do is find a small old lathe bed and experiment a little with it - see what can be done. That won't be for a while. I will document and photograph so that if a success others can see what has been done.
Michael

Michael, you have a precision cast straight edge the length of this bed?

.RC.
11-24-2010, 10:11 PM
http://www.machinetools.com/us/listings/view/fulltontech-fg200 (http://www.machinetools.com/us/listings/view/fulltontech-fg200)

That looks to me like 3, 4 to 5 metre long slant bed lathe bases sitting on a 20 metre table. Ex Dalian China. Will that fit in your shed?

About three quarters of it will :)

lazlo
11-24-2010, 10:17 PM
For my SAG12, I will check the alignment of these surfaces with my 6 ft camelback, a Starrett 199, and a small surface plate

John, I asked you this question in person: how are you going to spot the 6 foot camelback? It was an Ebay score, so you have to assume it's not flat. :)

Are you going to have the camelback ground at Commerce?

form_change
11-24-2010, 10:31 PM
I have a camelback (from memory) around 30" long and that's heavy enough to lift as it is. However, this should be long enough to bridge the main dips in the bed. I probably don't need that sort of precision anyway at the moment (it's been ground to microns) as in the first instance I was only intending to use feeler gauges to get a better map of the way deviations. It's one of those tools that only comes out occasionally but is used when nothing else will do the job. I bought it cheap at a junk shop where it was used as a door stop, reground it and it's fine.

Michael

TexasTurnado
11-25-2010, 12:13 AM
John, I asked you this question in person: how are you going to spot the 6 foot camelback? It was an Ebay score, so you have to assume it's not flat. :)

Are you going to have the camelback ground at Commerce?


That's another of the unknowns at this point. I asked Commerce about grinding it, but they were not keen on the idea - they said it heats up too much (even with the coolant flowing) to give good results. :( I have to assume this is from experience....

I have been watching for a 30 or 36 by 72 (or even 60) surface plate, but no luck so far. Maybe I can get them to kiss it off lightly so I can see where the problems are (or aren't)... :D

Actually, except for the gouges in the surface from careless handling, it doesn't look bad on the 5 ft diagonal of my 3 x 4 plate. The worst of these is about 1/8 wide and about .010 deep, but is diagonally across the face at one end.

Edit: It just occured to me, I can spot it on the flat way of the Colchester.... ;)

.RC.
11-25-2010, 01:01 AM
Edit: It just occured to me, I can spot it on the flat way of the Colchester.... ;)

I don't think ground surfaces will hold the blue...

beckley23
11-25-2010, 10:23 AM
Scraped surfaces are much better for spotting than ground surfaces.
A word about straight edges;
You are going to discover that using a camelback straight edge to spot an inclined surface, such as a V way, is extremely difficult, especially on the narrow inside faces found on a 10EE. I used a 4' camelback to spot the ways on my 12" CK Monarch, with a 7' bed length, and was very difficult to use on the V ways. The problem is holding it, and making sure there is good surface contact. You are holding it at the bottom, just above the flat, with the rest of it laying on your forearms. The 2-1/4" width of the flat doesn't help, when spotting a 3/4" wide surface. You've got to make sure that you're not rocking. The next time I scraped a bed, it was a 59" long 10EE bed, 30" centers, I made a new straight edge. I made it from 1-1/4" X 2" X 48" Meehanite, it weighs 40 LBS, the camelback weighs 37 LBS. It was a lot easier to manipulate than the camelback. I also used it to spot the front inside face of the V way on the Series 60 Monarch, approx 100" long. You do need to qualify the SE every now and then, and make very minor corrections, but this style does work.
Harry

Mcgyver
11-25-2010, 10:42 AM
That's another of the unknowns at this point. I asked Commerce about grinding it, but they were not keen on the idea - they said it heats up too much (even with the coolant flowing) to give good results. :( I have to assume this is from experience....


The issue I don't think is heat but temperature. Heat buildup can be eliminated with coolant but there is almost nothing you do about the very high temps where the molecule of grit hits the molecule of iron- its a function of cutting speed and coolant doesn't lower it much. I've heard stories of guys trying to grind wood plans and having them turn into bananas; I suppose because these high local temps altered the stress in the material. Incidentally wood plane soles greatly benefit from a scraping job imo.

I would not try grinding a straight edge for this reason, you risk destroying it and as noted a ground surface doesn't hold the blue very well. Also, how do you clamp it? What pains do you think a commercial grinder is going to take to ensure holding the dang thing creates zero distortion?


Edit: It just occurred to me, I can spot it on the flat way of the Colchester....
scraping to an existing way of course carries obvious problems, you don't know its condition or even if new you don't know that there's no twist in it. It might make for a quick and dirty check, but what if you spot you and get some weird pattern, are you going to have confidence in which one you scrape?

you can either buy three :eek: or a surface plate....or use someone else's. I've a 60" camel back sitting here waiting for the day a local guy lets me use his surface plate. The things are worth a small fortune and are a precision instrument that becomes the baseline for all your machines so it has to be done properly

Harry's right about weight of big straight edges. I'd thought of some sort of balance or zero gravity device, but haven't taken it further...spotting with a 60" camel back for sure is not a one man job...its all i can do to carry it around

TexasTurnado
11-25-2010, 12:49 PM
I don't think ground surfaces will hold the blue...

Not too well, but it does work - I had to do this to match the ts base to the newly ground ways on the Colchester (and also for the match to the saddle - although those were Turcite covered surfaces).

If I actually do use the flat way to check the st edge, it might be better to put the blue on the st edge and let the way show the high spots by removing or thining the blue....

Lazlo has cautioned me about using the 5 ft diagonal of the surface plate to spot the 6 ft camelback, as Forrest had problems using a short plate to spot a longer st edge in the past - here is the situation:

http://i288.photobucket.com/albums/ll168/TexasTurnado/P5260053.jpg

At worst, I can accurately spot the first 60 inches from either end and have confidence using that - the question is whether it will be accurate over the full 72 inches if I alternately spot from opposite ends...

lazlo
11-25-2010, 12:55 PM
I asked Commerce about grinding it, but they were not keen on the idea - they said it heats up too much (even with the coolant flowing) to give good results. I have to assume this is from experience....
The issue I don't think is heat but temperature. Heat buildup can be eliminated with coolant but there is almost nothing you do about the very high temps where the molecule of grit hits the molecule of iron- its a function of cutting speed and coolant doesn't lower it much.

What?? Are you saying that you can't surface grind iron?

Commerce doesn't want to grind camelbacks because they're long skinny pieces, and the heat will twist any asymmetry in the casting.


you can either buy three :eek:

Spotting long, skinny pieces against each other is an exercise in madness, as Forrest found :) The three plate method is very susceptible to twist: three plates shaped like potato chips will spot perfectly to each other.

That's why all the classic scraping manuals tell you to use square plates, and mark the corners when you're doing the three plate method. You're supposed to rotate each plate 90 each time you switch plates, which avoids matching potato chip warps.

http://i164.photobucket.com/albums/u15/rtgeorge_album/MooreTwistI.jpg
http://i164.photobucket.com/albums/u15/rtgeorge_album/MooreTwistII.jpg

TexasTurnado
11-25-2010, 12:56 PM
Scraped surfaces are much better for spotting than ground surfaces.
A word about straight edges;
You are going to discover that using a camelback straight edge to spot an inclined surface, such as a V way, is extremely difficult, .....
Harry

+1 on that, Harry! That was another factor that convinced me to take the Colchester bed to Commerce for grinding.... :D I have not weighed the 72 inch camelback, but it must be in the vicinity of 120 -150 lbs - it is all I want to move by myself, let alone try to hold on a sloped surface.

lazlo
11-25-2010, 01:06 PM
Lazlo has cautioned me about using the 5 ft diagonal of the surface plate to spot the 6 ft camelback, as Forrest had problems using a short plate to spot a longer st edge in the past

That was actually Harry who had problems using a short plate to spot a longer camelback, in the "Rebuilding a Monarch Lathe" in the mid 90's Home Shop Machinist articles. He describes that he spotted the camelback in sections, and didn't realize until deep into rescraping the Monarch bed that the camelback had a twist.

Connelly et al all tell you specifically not to spot long references on shorter surface plates for exactly that reason.



By the way, as far as ground spotting references: I bought a prismatic dovetail reference from *cough* Reliable on Ebay. It's the typical Cast iron polygon, with a steep angle cut for marking dovetails. I was surprised, when I received it, that it was ground on all sides. But the maker then added half-moon flakes to fill the spotting compound. It's marked "Property of the Martin Marietta Toolroom", and it marks-up dead-nuts on my surface plate. Spots really nicely too.

TexasTurnado
11-25-2010, 01:35 PM
Are you going to have the camelback ground at Commerce?

On a hunch, I just went out and measured the SAG12 bed - it is "only" 48 inches long, so I can further put off solving this problem. :D Even my 48 inch camelback should be long enough to spot the SAG 12.....

TexasTurnado
11-25-2010, 01:42 PM
That was actually Harry who had problems using a short plate to spot a longer camelback, in the "Rebuilding a Monarch Lathe" in the mid 90's Home Shop Machinist articles. He describes that he spotted the camelback in sections, and didn't realize until deep into rescraping the Monarch bed that the camelback had a twist.


Oops, my memory is not what it use to be....:)

But that presents me with an opportunity to ask Harry directly if he thinks the extra 12 inches can be accurately spotted on the diagonal of my plate - what do you think, Harry? There is quite a bit of overlap, but is it enough?

Richard Wilson
11-25-2010, 02:23 PM
[QDon't get hung up on measuring wear if the machine still produces results which are acceptable for your sort of work.

Richard[/QUOTE]
All of this stuff with camelbacks etc is fascinating, but still unanswered is the point I tried to make earlier, does the machine produce results good enough for what the OP needs it to do, and will the grinding, scraping etc etc be worth all the considerable effort?

Richard

Mcgyver
11-25-2010, 04:05 PM
What?? Are you saying that you can't surface grind iron?

Commerce doesn't want to grind camelbacks because they're long skinny pieces, and the heat will twist any asymmetry in the casting.

Spotting long, skinny pieces against each other is an exercise in madness, as Forrest found :) The three plate method is very susceptible to twist: three plates shaped like potato chips will spot perfectly to each other.



i wasn't really advocating generation, just listing it as one way it could be done....smiley meant i wasn't seriously recommending it. It would be like walking across the country to avoid bus fair....unless walking across the the country is someone's thing, it doesn't make much sense; too much work

I've ground lots of cast iron so its not that, and heat can be controlled with coolant....but the high localized temps from grinding can cause problems with warping. Perhaps I'm not using the right terminology but i think its a temperature issue vs a heat issue...but we often interchange the two. As was explained to me by tool and die guys, grinding can warp parts because of the high temps at the point of contact even with no overall temp change in the work (because of coolant). I think we're say thing same thing though??; the grinding temperatures on a shape like that risk warping it, not because its cast iron.

Whether you need to worry about it is I think dependent on the shape/size of the work. Chunky solid pieces less a concern than thin sections. I heard of wood planes drastically changing shape so imo its a risk.... like a wood plane its a small cross section compared to its overall size and mass so might be a likely candidate for trouble.....and as a reference tool its where you don't want trouble

Plus ground doesn't take blue well and it would be tough to hold without twisting it. I'd even throw into the nay pot the argument that surfacing a reference tool should be done with something more accurate than another machine's ways which you're getting if you grind it....all ads up to me being of the opinion grinding a straight isn't a good idea.

.RC.
11-25-2010, 04:14 PM
Wouldn't it be easier to measure bed wear with a precision level?

This is how it is explained in Michael Morgans book.

http://img.photobucket.com/albums/v606/OzRinger/machinetoolreconditioning001.jpg

This is how I plan to measure the wear in the V ways on my purcell lathe

http://img.photobucket.com/albums/v606/OzRinger/Cert3LCM010Custom.jpg

lazlo
11-25-2010, 04:14 PM
I've ground lots of cast iron so its not that, and heat can be controlled with coolant....but the high localized temps from grinding can cause problems with warping.

Wow, I've surface ground a bunch of cast iron references: angle blocks, toolmaker's knees -- even that neat little Eclipse reference block you sent me. They all turned out mirror smooth, with a spotless surface when marked on my surface plate.


Plus ground doesn't take blue well and it would be tough to hold without twisting it.

No doubt. I'm sure the latter is a major reason why Commerce doesn't like to grind camelbacks. But as I pointed out above, you can half-moon flake the surface to get good spotting. I'll take some picture of my Martin-Marietta reference after I pass out from turkey :)

John: you probably remember -- I have a Biax power flaker if you want to borrow it.

beckley23
11-25-2010, 04:25 PM
When I originally scraped the 4' SE, I used the wrong method. I have an 18" X 24" surface plate, across corners it's about 30". When I did it the first time, I alternated ends for spotting and scraping. Bad choice. When I discovered the problem, I started at one end and prgressively moved down in 6-8" increments. Each section is finished before moving to the next, and I only scraped the next section. You should see the flat developing, and when spotting in the old and new sections shows up you know you're almost there. Get the meeting blended and you're ready to advance to the next section. It was a hard lesson in what not to do, but it didn't cost that much timewise in the overall job. I appllied what I learned to the way scraping.
When I scraped the "new" straight edge, I picked up a 24" X 36" surface plate, it isn't perfect, but I can't tell from the results I'm getting on the "Wreck" or the Series 60.
BTW, "Reconditioning a Lathe-Revisited" , the 1st installment started in the Sep/Oct 2004 issue of HSM, and ran for 4 issues. The original Reconditioning article appeared Jan/Feb 1984 HSM. It was about a 13" Sheldon.
Harry

form_change
11-25-2010, 04:27 PM
Richard, in answer to your question "yes and no". The wear on carriage ways does not affect what I do. As someone has calculated the vertical wear I have is only changing the diameter at around the 14th decimal place.
The tailstock is another matter. As I said very early on in the thread as it currently is I get bell mouthed holes and can snap drill bits easily due to vertical misalignment. Several respondents have suggested shimming the TS but the ways are worn there too, so to fix the TS 'properly' the ways should ideally be reground (and once the machine is set up for grinding...)
It gets more complicated - via PM it has been pointed out to me from the symptoms I have the carriage is worn enough to be rubbing directly on the bed and I may also have preferential wear on one side of the carriage V way. As a result I want to do more checks when I replace the oil valves and the carriage is removed from the bed. I have already seen that I can't get a 1.5 thou feeler between the bed and carriage so there is contact.
The least I feel I must do at the moment is relieve the carriage (avoid further wear), replace the oilers (ensure lubrication is present) and shim the TS (fix the drilling issues). A professional bed grind would a good thing to add to the list but financially that's out of the question.
While I occasionally get to repair machine tools at work this activity is a hobby for me to make up for the frustration of working in a manufacturing company's quality department. (No one listens when you say that a process won't produce results to spec, but everyone holds you responsible when you stop the crap they have made going out the door). As a result the considerable effort does not concern me as much provided the end result is an improvement.

Michael

Mcgyver
11-25-2010, 04:31 PM
Wow, I've surface ground a bunch of cast iron references: angle blocks, toolmaker's knees -- even that neat little Eclipse reference block you sent me. They all turned out mirror smooth, with a spotless surface when marked on my surface plate.


So have I - they are all more solid shapes than the more latice like camel back. I qualified it by saying the risk factor is tied to the shape.....so plane bodies are risky, V blocks aren't...strikes me that camel backs probably are.....and that its the shape/section that is the concern not that its cast iron - its an issue with any material (depending on the section of course!)

This isn't something i can testify to in court, just a lot anecdotes suggesting the more latice like or lightly structured the peice is the more likely it is that high grinding temps will cause warpage - but aren't you basically saying the same thing when you said they would want to grind it because the heat could warp it?..... so i'm confused :confused:

form_change
11-25-2010, 04:39 PM
RC I have done that one as well. It will produce a result but has two caveats to it -
It give a result as slopes (inclination) so extra head work is required to work out what the surface is doing.
You are comparing between two points, so any local dips are not necessarily found.
The other problem is that the levels are very sensitive (mine is around 0.04mm per metre) so the item being measured has to be close to level anyway. I checked my surface plate once and found I had to shim a side a fraction of a mm just so the level vial could be on centre, even though the 'normal' level I used to set up the table had said it was fine.

Michael

.RC.
11-25-2010, 04:39 PM
Richard, in answer to your question "yes and no". The wear on carriage ways does not affect what I do. As someone has calculated the vertical wear I have is only changing the diameter at around the 14th decimal place.


But that is on the assumption that the wear is even on both ways..

I know this is not the case on my purcell lathe and the saddle not only moves up and down as it travels along the bed but in an arc as well moving the tool in and out from the workpiece...

My tailstock is the same, and I like on your lathe is the worse problem then worn carriage ways..

Forrest hammers the message time and time again that when you start to undertake a reconditioning job the first thing you must do is a survey of the machine to find out first where the wear is. And write it all down in a notebook..

I was thinking in bed last night of other ways to measure V-wear and came up with an idea of using a dial indicator if you have an unworn reference plane to use... Often the flat bits between the ways is unworn and in the same plane as the ways... I believe you can use this as the required reference...

oldtiffie
11-25-2010, 04:52 PM
Michael.

Good down-to-earth practical assessment and costs benefits analysis with a cap on costs etc.

The tail-stock wear and its follow-on problems are in two parts - ie wear on the under-side of the TS base and the tops of the TS ways on the lathe bed.

Why not address them as separate but related problems/issues?

As the bed seems to be going to be left largely "as is", and as the TS is a smaller item that can be done locally/in-house and/or off-site, why not do the TS?

As the TS is "soft" - ie not induction or other-wise hardened - the base could be done on a shaper or a mill and a grinder followed up by hand-scraping as normal if or as required? Any build(ing)-up and/or packing or shimming can be incorporated in the scope of works.

An "improved" TS should at least solve part of the problem.

The rest of the scope of works could be done piece-meal or incrementally over time as time, space, use of the lathe and cash require or allow.

I have no problem with high-class work when it is needed or necessary for the sake of it but I am usually more inclined to work "to the degree necessary" to get the job functional and usable and "fit for purpose".

lazlo
11-25-2010, 04:54 PM
the more latice like or lightly structured the peice is the more likely it is that high grinding temps will cause warpage - but aren't you basically saying the same thing when you said they would want to grind it because the heat could warp it?..... so i'm confused :confused:

I guess I'm confused by the comment that:


" the high localized temps from grinding can cause problems with warping.

grinding can warp parts because of the high temps at the point of contact even with no overall temp change in the work (because of coolant). "

I think it's simply the case that the grinding process is heating the casting, and long skinny pieces, especially with a highly asymmetric casting like a camelback, will twist from the heat. So you end up grinding a noodle, and when it cools back down, it's a twisted mess.

But it has nothing to do with cast iron -- in fact, gray cast iron has a much lower coefficient of thermal expansion than steel. That's one of the reasons it's used in metrology references.

In other words, a long, thin, asymmetric steel casting will warp even worse, as anyone who'd ground thin flat stock can attest.

oldtiffie
11-25-2010, 05:22 PM
I don't think so.

The linear and volumetric co-efficients of iron and steel are very similar with each about 11 and 33 respectively.

http://en.wikipedia.org/wiki/Coefficient_of_expansion#Thermal_expansion_coeffic ients_for_various_materials

Mcgyver
11-25-2010, 05:45 PM
I think it's simply the case that the grinding process is heating the casting, and long skinny pieces, especially with a highly asymmetric casting like a camelback, will twist from the heat. So you end up grinding a noodle, and when it cools back down, it's a twisted mess.


I agree asymmetrical shapes will likely cause more trouble, and if I left the impression that this was a cast iron issue then that was in error. but its more than a heat issue....you can keep the entire workpiece at room temperature via coolant...except at the point of contact, and still have warping problems when grinding. In that case, heat, ie coefficient of expansion over the whole piece, isn't an issue because its not present....flood keeps it at room temp. Its the very high temps right where the grinding takes place that messes things up. I can't offer science on it beyond that, it was taught to me by a tool and die friend as some ever present when grinder to be aware of ....and that where its a problem will be a function of the section. As i say, I wouldn't swear to it but it seems to hold true and there's anecdotal support for it to the extent I wouldn't risk it on something like a camelback - the risky profile, expensive and needs to be dead on.

oldtiffie
11-25-2010, 06:15 PM
I'd go along with the grinding perhaps being a problem with the camel-back, but if the same physics apply generally, it would suggest that the lathe will distort under grinding - and yet those lathe beds that are ground seem to be very/quite accurate after grinding.

A previous set of pics posted here showed 0.014" (as I recall) "shaved off" but the lathe bed was apparently quite/very accurate after that heavy grinding.

The OP's lathe would seem to need about 0.008" (as I recall) ground off - assuming that is the only planar error - and that a "witness" was left.

All too often the biggest problem with grinding is fine wheels and too deep a depth of cut - and/or too slow a feed rate and the wheels getting "clogged" and/or "blunt" and doing more rubbing than cutting - and needing frequent (re)dressing.

I use the coarsest wheel that I can lay hands on to get the bulk of material off, let the job (unclamped) settle to ambient shop temperate, and then finish grind (a "medium" wheel is good enough most times).

TexasTurnado
11-25-2010, 06:43 PM
When I originally scraped the 4' SE, I used the wrong method. I have an 18" X 24" surface plate, across corners it's about 30". When I did it the first time, I alternated ends for spotting and scraping. Bad choice. When I discovered the problem, I started at one end and prgressively moved down in 6-8" increments. Each section is finished before moving to the next, and I only scraped the next section. You should see the flat developing, and when spotting in the old and new sections shows up you know you're almost there. Get the meeting blended and you're ready to advance to the next section. It was a hard lesson in what not to do, but it didn't cost that much timewise in the overall job. I appllied what I learned to the way scraping.
When I scraped the "new" straight edge, I picked up a 24" X 36" surface plate, it isn't perfect, but I can't tell from the results I'm getting on the "Wreck" or the Series 60.
BTW, "Reconditioning a Lathe-Revisited" , the 1st installment started in the Sep/Oct 2004 issue of HSM, and ran for 4 issues. The original Reconditioning article appeared Jan/Feb 1984 HSM. It was about a 13" Sheldon.
Harry

That's good info, Harry - thanks for posting it. Now I have "a plan of attack" when this item comes up again - it's currently pretty far down on the list of things to do..... :D

oldtiffie
11-25-2010, 11:32 PM
I agree asymmetrical shapes will likely cause more trouble, and if I left the impression that this was a cast iron issue then that was in error. but its more than a heat issue....you can keep the entire workpiece at room temperature via coolant...except at the point of contact, and still have warping problems when grinding. In that case, heat, ie coefficient of expansion over the whole piece, isn't an issue because its not present....flood keeps it at room temp. Its the very high temps right where the grinding takes place that messes things up. I can't offer science on it beyond that, it was taught to me by a tool and die friend as some ever present when grinder to be aware of ....and that where its a problem will be a function of the section. As i say, I wouldn't swear to it but it seems to hold true and there's anecdotal support for it to the extent I wouldn't risk it on something like a camelback - the risky profile, expensive and needs to be dead on.

I think that the main problem with grinding hardened and perhaps brittle tool-steel - which may be rapidly heated and cooled progressively as the grinding proceeds - is "micro-crack(ing)" fracturing which can ruin a tool or reduce its operational life or periods/cycle between re-conditioning or re-sharpening or replacement.

While it is a long shot with the induction (or any) hardened surface it should not significantly affect the non-hardened cast iron. The mass of the cast iron, while a restraint to expansion and contraction, is quite ductile, it is also a good conductor of heat and a good heat-sink.

I'd be more concerned about ambient temperate differences and fluctuations as well as "wind heat/chill" in the shop during the process of the works.

I am with the OP as I'd leave the lathe bed "as is" and just do up the tail-stock to a functionally adequate level.

I'd be surprised if a few representative test cuts showed any significant errors on the lathe as it is now.

These should be done anyway as part of the evaluation process and to provide a bench-mark and a definition of required scope/s of work.

.RC.
11-26-2010, 04:22 AM
The solution to this problem just dawned upon me....

All depends on how accurate a job you want and making an accurate map of where the wear is and how much wear there is...

A sled with CNC controlled downfeed.. Modern CNC machines have error correction where they can make a surface truer then the slides of the machine if the machine knows where the error is and can compensate as required...

Might take a bit to work out but I cannot see why it would not work...

luthor
11-26-2010, 07:00 AM
But it has nothing to do with cast iron -- in fact, gray cast iron has a much lower coefficient of thermal expansion than steel. That's one of the reasons it's used in metrology references.

In other words, a long, thin, asymmetric steel casting will warp even worse, as anyone who'd ground thin flat stock can attest.

I think you have it the wrong way around Lazlo, Steel actually has the lower expansion according to the Machinerys Handbook. The difference is only.00000022"/inch/deg F so lets just say they are the same.

oldtiffie
11-26-2010, 07:49 AM
This is going to send the purists to the Wailing Wall, but not so long ago the OP's bed would have been put on a planer to get quite a good finish and degree of accuracy and then hand honed and/or scraped if and as required to the degree necessary.

There are some quite large bridge (vertical) mills that are very accurate and more then large enough for that job on the OP's lathe bed. They are precision CNC/NT-controlled and very versatile. The finish will be first class and may only need scraping to "cosmetic", "touch-up" or lubrication purposes.

My guess is that if the OP asked around the traps in Adelaide (OZ) he may well find one.

If the OP's lathe bed is hardened it may need to be ground, but if the depth of cut is in the order of 0.008" there won't be much if any of the hardened surface/s left.

If it were me, I'd check the lathe with some representative test cuts (without using the tail-stock) to see just how good or bad the machine is in terms of what the OP wants or needs the lathe to do.

As I said previously, I'd be more inclined to tackle the tail-stock first if needs be.

If I went the "whole bit", I'd include the saddle ways and the cross and top slide dove-tails at least.

Greg Q
11-26-2010, 08:11 AM
If I went the "whole bit", I'd include the saddle ways and the cross and top slide dove-tails at least.

Those items will have to be scraped for alignment and bearing in any event, and perhaps flaked too for oil retention. It is an article of faith that wear in hardened beds will be about 20% of the wear that the saddle will suffer. Milling may be the best bet for the saddle, followed by replacement material. (Garlock, moglice, metal spray, etc). Finally scraping for bearing using the restored ways as a reference.

The traditional order of operations is top slide first, then cross slide, then saddle/bed, then bed. You cannot justify spending time on the beds without addressing the other elements of the equation too.

Greg

oldtiffie
11-26-2010, 09:11 AM
That makes sense Greg as with 0.008" wear in the saddle ways on the bed the saddle is all but or actually is riding on or fouling the lathe bed.

Some others need to think this out as when the tool is loaded up when cutting on the job, the force required to advance the tool is applied by the saddle gearing to the rack. This causes a big turning moment on the saddle as the is quite a horizontal separation between the tool cutting-edge and the rack.

This turning moment is more often than not - with relatively light cutting - is resisted by the weight of the saddle.

With heavier cutting, the resistance to up-lift by the saddle is inadequate as the additional load and turning moment/s will tend to cause the saddle to slide/climb up the ways until it is resisted by the stop plate on the under-side/s of the saddle which engage/s the machined face/s under the lathe bed. Needless to say, these gaps have to be kept to a practical minimum so as to minimise saddle up-lift under heavy loads.

Any wear or material removal from the top of the lathe bed ways and any that is removed from the saddle ways will not only be added to the gaps referred to but will cause the saddle gears to move further out of mesh with the rack but will also cause misalignments between the lead-screw, the power feed shaft and the start/stop shaft as their end bearings will no longer be aligned to the saddle either.

And so it goes.

moe1942
11-26-2010, 10:27 AM
Has moglice been mentioned yet?? I know nothing about it but have seen others mention its use in way repair.

http://www.moglice.com/

lazlo
11-26-2010, 11:04 AM
I think you have it the wrong way around Lazlo, Steel actually has the lower expansion according to the Machinerys Handbook.

Note that I said gray cast iron. The graphite flakes act like a compression spring, and absorb the movement of the iron grains as they expand.

Gray cast iron has one of the lowest Coefficients of Linear Thermal Expansion (CTE) of any "common" material: 5.8 x 10-6 inch per F

Ductile cast iron is 6.6 x 10-6 inch per F

Steel's CTE is ~ 20% greater than gray cast iron: 7 x 10-6 inch per F

http://i164.photobucket.com/albums/u15/rtgeorge_album/CTE-2.png

A good quote from one of my foundry books:


"Gray irons, especially those with a low C.E. offer excellent shape stability, even at very high temperatures. Warping remains minimal until resistance drops to very low values. This characteristic is almost unique to Gray iron."

The low coefficient of expansion of grey cast iron is the reason Moore et al use grey cast iron rather than ductile for surface plates, scraping masters, et al. There are even grey cast iron alloys with a high nickel content that have CTE's that approach Invar (in the 0.68 x 10−6 in per F range).

TexasTurnado
11-26-2010, 12:39 PM
Any wear or material removal from the top of the lathe bed ways and any that is removed from the saddle ways will not only be added to the gaps referred to but will cause the saddle gears to move further out of mesh with the rack but will also cause misalignments between the lead-screw, the power feed shaft and the start/stop shaft as their end bearings will no longer be aligned to the saddle either.

And so it goes.


Indeed, which is precisely why products like Moglice, Turcite, etc were developed. I used Turcite, and by choosing the appropriate thickness and carefully calulating the amount of metal to be machined off, the saddle can be repositioned correctly:

http://i288.photobucket.com/albums/ll168/TexasTurnado/P8200053.jpg

oldtiffie
11-26-2010, 03:10 PM
Thanks TT - good advice.

There is or can be a lot of difference between scraping with and/or without grinding - or vice-versa - and restoration of a machine.

I have no issue with anyone who chooses to under-take that task. Nor have I any issue with any who either only do as much as is needed - or who for their own reasons do little or nothing at all.

J Tiers
11-28-2010, 01:17 PM
Lazlo has cautioned me about using the 5 ft diagonal of the surface plate to spot the 6 ft camelback, as Forrest had problems using a short plate to spot a longer st edge in the past -



I can vouch for the issues..... I think it actually can work, but GETTING it to work is not as easy as it seem that it would be. Even with a shorter S.E.

It seems to end up being similar to the issue of pressing harder on one end than the other.... affects the bluing, and also can drive you crazy with rocking on the "edge" of the area not yet scraped.

oldtiffie
11-28-2010, 05:51 PM
I can't see where a large straight edge as part of a bed-scraping process is relevant if the bed is hardened or unless or until the bed is ground down until the hardening on the part or surface to be scraped is removed.

If the bed is precision-ground, why scrape it flat(ter?).

If the bed is as flat as that it could or should be used as the reference for (filling and?) machining and scraping the under-side of the saddle (and the cross and top slides) as its not likely those surfaces - before or after filling - will be hardened.

If the bed were not hardened but was precision ground, I can see the sense in scraping it for lubrication (and "looks"?) but not for "flat" as the grinding process should take care of that.

But, if on the other hand, for what ever reason, someone wants to scrape it if or when its not really needed - good for them.

beckley23
11-28-2010, 06:50 PM
If you're having rocking problems spotting across corners, spot going the length of the surface plate for a few cycles, and cross check across corners, eventually you will get to a point when the shorter length spotting isn't necessary.
I had rocking problems when I initially started the scraping after milling on my custom SE, but after a few cycles it ceased, and I never used the short spotting sequence.
IMO, this rocking issue is a minor problem that goes with the territory, and you will quickly learn to deal with it.
Harry

J Tiers
11-28-2010, 07:32 PM
The rocking is a lesser issue, I think.

The bigger one seems to be an inherent difference in spotting, possibly due to the overhanging weight on a longer-than-plate straight edge. That will depend on how much longer it is.

Theoretically, you should be able to basically bring a section of the SE to a flattish condition, and then bring the rest down to meet it. It does not seem to work quite that way in practice, or perhaps it is better to say "that isn't what it LOOKS like when you actually do that process" (whether or not that is actually what is really happening).

oldtiffie
11-28-2010, 08:15 PM
I think some things need to be (re-)said and (re-)considered.

Ideally, the surface plate used to check or for scraping-in the camel-back (or anything else) needs to be at least one grade better than the camel-back etc. and the camel-back when scraped-in needs to be at least one grade better than the lathe bed or what-ever else it is used to check.

The surface plate needs to be at least two grades better than the lathe bed etc.

So,if you want a really really good lathe bed you are going to need a better camel-back etc. and the camel-back etc. is going to a top-notch surface plate.

As the ultimate reference here is the surface plate it should be at least Grade AA and be "mapped" to see where the optimum flatness is for checking the camel-back.

If the surface-plate is Grade AA (reference grade), the camel-back can only be assumed to be grade A (Inspection Grade) at best and the lathe bed at Grade B (Shop Grade).

Here is my Grade AA (Chinese) "map" for my 400mm x 300mm surface plate. Units are in micro-meters (aka "microns") and are ~ "4 tenths":
http://i200.photobucket.com/albums/aa294/oldtiffie/Surface%20plate/Surfplategradediag1.jpg

The "best diagonal" for checking (the camel-back etc) is from top-left to bottom-right as there is only a 0.12um (0.0004 x0.12 ~ 0.00005 ~ half a tenth) "bump" in the centre.

The other (bottom-left to top-right) has a 0.37um "dip/hollow" ie 0.0004 x 0.37 ~ 0.00015" (~ 1.5 tenths).

And so it goes.

I will address using the camel-back in other than the vertical shortly.

TexasTurnado
11-28-2010, 09:02 PM
I can't see where a large straight edge as part of a bed-scraping process is relevant if the bed is hardened or unless or until the bed is ground down until the hardening on the part or surface to be scraped is removed.

If the bed is precision-ground, why scrape it flat(ter?).

If the bed is as flat as that it could or should be used as the reference for (filling and?) machining and scraping the under-side of the saddle (and the cross and top slides) as its not likely those surfaces - before or after filling - will be hardened.

If the bed were not hardened but was precision ground, I can see the sense in scraping it for lubrication (and "looks"?) but not for "flat" as the grinding process should take care of that.

But, if on the other hand, for what ever reason, someone wants to scrape it if or when its not really needed - good for them.

There is a legitmate use of a st edge for a hard bed and scraping the ways with carbide, but I brought up the subject of the st edge for checking the coplanar issues where the surfaces of the bed mate to the base.

J Tiers
11-28-2010, 09:46 PM
I think some things need to be (re-)said and (re-)considered.

Ideally, the surface plate used to check or for scraping-in the camel-back (or anything else) needs to be at least one grade better than the camel-back etc. and the camel-back when scraped-in needs to be at least one grade better than the lathe bed or what-ever else it is used to check.

The surface plate needs to be at least two grades better than the lathe bed etc.

So,if you want a really really good lathe bed you are going to need a better camel-back etc. and the camel-back etc. is going to a top-notch surface plate.


B'rouf....

All very well...........

However, for someone who states that they have 5 to 8 thou of dips in their bed, NOT equal between the two ways the carriage travels, it is perhaps less than top level on the list...... With the front way dipping and the back way NOT dipping, the effect on workpiece diameter is very much larger than for an equal dip..... perhaps not 1:1, but likely 1:3, perhaps 1:4 or so.... for a possible variation of up to 2 or 3 thou on the work.

For that situation I very much suspect that traceability specs to the national laboratory is secondary to getting the roller-coaster fixed up to a dull rattle. A good solid half a thou or even 0.75 thou variation is going to make that person quite happy (especially if the differential variation is fixed), and it should.

TexasTurnado
11-28-2010, 09:48 PM
I think some things need to be (re-)said and (re-)considered.

Ideally, the surface plate used to check or for scraping-in the camel-back (or anything else) needs to be at least one grade better than the camel-back etc. and the camel-back when scraped-in needs to be at least one grade better than the lathe bed or what-ever else it is used to check.

The surface plate needs to be at least two grades better than the lathe bed etc.


I don't think I agree that one loses an arbitrary grade as indicated above....

I don't know what the typical thickness of marking dye is, but I do know some use alcohol for the most exacting uses. And I don't think the error is anything like .0001 inch difference between the master plate and a st edge properly scaped to it. I remember being surprised at just how sensitive the scraping process was when I first started.

The plate you mentioned above in not big enough to be useful with a long st edge, but if it was, I think you would find distintively different markings on the alternate diagonal if accurately scraped to the other one.

Which does support the idea a map of the errors would be quite useful..... I don't remember getting such a map with my grade A (I could not find an AA plate in a 3 x 4 ft size) plate - just a certificate it had a certain max error (from an American co even though it came from China).

oldtiffie
11-29-2010, 01:58 AM
Originally Posted by oldtiffie
I can't see where a large straight edge as part of a bed-scraping process is relevant if the bed is hardened or unless or until the bed is ground down until the hardening on the part or surface to be scraped is removed.

If the bed is precision-ground, why scrape it flat(ter?).

If the bed is as flat as that it could or should be used as the reference for (filling and?) machining and scraping the under-side of the saddle (and the cross and top slides) as its not likely those surfaces - before or after filling - will be hardened.

If the bed were not hardened but was precision ground, I can see the sense in scraping it for lubrication (and "looks"?) but not for "flat" as the grinding process should take care of that.

But, if on the other hand, for what ever reason, someone wants to scrape it if or when its not really needed - good for them.


There is a legitmate use of a st edge for a hard bed and scraping the ways with carbide, but I brought up the subject of the st edge for checking the coplanar issues where the surfaces of the bed mate to the base.

Thanks TT.

Actually, there is quite a possibility that a plane could have a lateral twist in it and the straight edge may not pick it up - but a good precision level should - if the ends/corners of or defining the plane are leveled.

Example: get a bit of sheet metal with a fairly high length:width ratio and twist the ends slightly. Now put a level on the diagonal that the sheet metal plate is twisted about. Surprisingly small isn't it? The more so in a case of a narrow face measured with a straight edge on a plate or surface with a very slight or small twist as in the case of a machine/lathe bed.

The camel back is very good if used vertically - as on a flat surface - as the camel-back is made with a parabolic curve (and strut) which has a very low deflection and a very high resistance to deflection in the vertical plane. Its resistance to deflection - and distortion - reduces as or if the level in moved from the vertical toward or to the horizontal. Once the level departs from the vertical its calibration is or becomes invalid. This applies if the level is uses on the "vee-way" faces of a lathe bed way - ie the "prismatic" faces.

Checking and scraping to or of a single or pair of prismatic faces is several orders of magnitude of skill and difficulty above compared to flat level faces.

If a say camel-back level is longer than the diagonals of a surface plate and can physically be seen or felt to "rock" (from side to side) it is unlikely to be the surface plate and frankly, the level needs to be a lot flatter before it goes on the surface plate.

I don't think I'd fancy scraping a hardened bed or surface at all as even frequent re-sharpening of a Bi-ax (power) scraper TC-tipped blades is a PITA.

oldtiffie
11-29-2010, 02:09 AM
Originally Posted by oldtiffie
I think some things need to be (re-)said and (re-)considered.

Ideally, the surface plate used to check or for scraping-in the camel-back (or anything else) needs to be at least one grade better than the camel-back etc. and the camel-back when scraped-in needs to be at least one grade better than the lathe bed or what-ever else it is used to check.

The surface plate needs to be at least two grades better than the lathe bed etc.

I don't think I agree that one loses an arbitrary grade as indicated above....

I don't know what the typical thickness of marking dye is, but I do know some use alcohol for the most exacting uses. And I don't think the error is anything like .0001 inch difference between the master plate and a st edge properly scraped to it. I remember being surprised at just how sensitive the scraping process was when I first started.

The plate you mentioned above in not big enough to be useful with a long st edge, but if it was, I think you would find distinctly different markings on the alternate diagonal if accurately scraped to the other one.

Which does support the idea a map of the errors would be quite useful..... I don't remember getting such a map with my grade A (I could not find an AA plate in a 3 x 4 ft size) plate - just a certificate it had a certain max error (from an American co even though it came from China).

Thanks again TT.

I will try to find the limits of flatness for a 3 foot x 4 foot Grade A surface plate (NIST standard) and will work out the tolerance/s over the 5 foot diagonal of the plate. I will post it here later. You might be surprised at just how much variation (in "tenths") that is allowed.

There should be no good reason the better diagonal (5 feet) should not be adequate to scrape or check your level to.

But having said that, I'd think the surface transposed from the Grade A plate to the lathe bed would be Grade B at best. (I will work that out as well).

oldtiffie
11-29-2010, 02:22 AM
Originally Posted by oldtiffie
I think some things need to be (re-)said and (re-)considered.

Ideally, the surface plate used to check or for scraping-in the camel-back (or anything else) needs to be at least one grade better than the camel-back etc. and the camel-back when scraped-in needs to be at least one grade better than the lathe bed or what-ever else it is used to check.

The surface plate needs to be at least two grades better than the lathe bed etc.

So,if you want a really really good lathe bed you are going to need a better camel-back etc. and the camel-back etc. is going to a top-notch surface plate.


B'rouf....

All very well...........

However, for someone who states that they have 5 to 8 thou of dips in their bed, NOT equal between the two ways the carriage travels, it is perhaps less than top level on the list...... With the front way dipping and the back way NOT dipping, the effect on workpiece diameter is very much larger than for an equal dip..... perhaps not 1:1, but likely 1:3, perhaps 1:4 or so.... for a possible variation of up to 2 or 3 thou on the work.

For that situation I very much suspect that traceability specs to the national laboratory is secondary to getting the roller-coaster fixed up to a dull rattle. A good solid half a thou or even 0.75 thou variation is going to make that person quite happy (especially if the differential variation is fixed), and it should.

Thanks JT.

I used the measured wear figures (X 0.001" over and at 4" intervals) for the OP's lathe earlier in this thread. They were not too bad at all really as regards functionality (I did the indicative math for that as well), but the main problems seem to be that the wear in the carriage/saddle vee-ways will be several times that of the bed ways, and further, the OP cannot fit a 0.0015" feeler between the saddle in the "worst wear"(and "most used"??) part/s of the bed so there is little chance of removing much or any more than 0.008" from the lathe bed at this stage. The OP has said that he does not want to re-condition the saddle or the tail-stock at this stage.

oldtiffie
11-29-2010, 03:58 AM
Originally Posted by oldtiffie
I think some things need to be (re-)said and (re-)considered.

Ideally, the surface plate used to check or for scraping-in the camel-back (or anything else) needs to be at least one grade better than the camel-back etc. and the camel-back when scraped-in needs to be at least one grade better than the lathe bed or what-ever else it is used to check.

The surface plate needs to be at least two grades better than the lathe bed etc.

I don't think I agree that one loses an arbitrary grade as indicated above....

I don't know what the typical thickness of marking dye is, but I do know some use alcohol for the most exacting uses. And I don't think the error is anything like .0001 inch difference between the master plate and a st edge properly scaped to it. I remember being surprised at just how sensitive the scraping process was when I first started.

The plate you mentioned above in not big enough to be useful with a long st edge, but if it was, I think you would find distintively different markings on the alternate diagonal if accurately scraped to the other one.

Which does support the idea a map of the errors would be quite useful..... I don't remember getting such a map with my grade A (I could not find an AA plate in a 3 x 4 ft size) plate - just a certificate it had a certain max error (from an American co even though it came from China).

OK TT.

I went looking at the "Starrett" site for the formula (NIST applicable) for the required accuracy (measured across the diagonals) for all grades and sizes of surface plates and came across this Starrett link first.

http://ecatalog.starrett.com/Default.aspx#401

The tolerance for 4 foot x 3 foot (1200 x 900mm) plates are:

Grade AA (Reference): 0.00020" (2 tenths) and 0.005mm (5 um)

Grade A (Inspection): 0.00030" (3 tenths) and 0.0076mm (7.6um)

Grade B (Tool Room): 0.0008" (8 tenths) and 0.0203mm (20.3um)

The accuracy is reduced by half with each step/grade down.

Given that its more likely than not that the camel-back level will be no better than your grade A plate the accuracy of the level will be no better than 0.0003" (3 tenths) at best and more likely to be at or approaching Grade B (0.0008" = 8 tenths).

It is not likely that the lathe/machine bed/part will be better then Grade B and probably less.

Any "certificate" for a surface plate will have a limited life and NIST requires that they be re-calibrated and if necessary reconditioned periodically otherwise they are classed/regarded as "out of test".

I would be VERY careful when buying a used surface plate - for obvious reasons.

It should be obvious why I required - and got - the "map" of my surface plate.

The OP, in an earlier post, said he was employed in a manufacturing enterprise "Inspection" department/section which I guess means Metrology, so he should be aware of all of this.

Precision grinding (or the scrap heap) is looking better by the minute after the lathe is no longer performing well enough for the OP's purposes and requirements.

I will continue to chase up the NIST formulas for surface plates.

oldtiffie
11-29-2010, 05:24 AM
Here are some "good reads" on surface plates:

http://www.tru-stone.com/pages/forms_lit.asp

See page 6 here of US Government Spec. GGG-P-463e which is probably the standard to which all USA-made surface plates were made. The latest and ISO and NIST standards are only relatively minor up-dates of the spec.

http://www.tru-stone.com/pdf/FedSpecGGG-P-463c.pdf

Table 113 (page 6) spells it all out.

http://www.jwdonchin.com/Starrett/Catalog/pdf/481.pdf

http://www.qualitydigest.com/aug03/articles/03_article.shtml

http://www.google.com.au/#hl=en&source=hp&biw=1259&bih=494&q=surface+plate+calibration&rlz=1W1IRFC_en&aq=2&aqi=g10&aql=&oq=surface+plate&gs_rfai=&fp=9914a78f68f001bf

http://www.tru-stone.com/pages/smp.asp

J Tiers
11-29-2010, 09:45 AM
Tiffster:

Point being that it is NOT a case of "you gotta do it this way, or you can't do it at all".

If the bed is a roller coaster, and the OP SEEMS to have stated he does not want to do ANY of the standard things to be done (grind bed, recondition saddle and T/S).

Faced with that, basically any legitimate grade of straight edge can be used as a reference to generate a flat surface that will be one or two orders of magnitude* better than what he states he has.

I personally believe he might be well served by turning the machine on and using it, and THEN deciding if his results justify more work.

But if he has to "get into it", and is NOT going to send it out for grinding, etc, there is no need to get shirty about the grade of reference tool. It is bound to be better than using one part of the roller coaster to flatten another part........

of course we are limited to the information released, who knows if there is more info that affects the decision. Maybe the bed is NOT that bad, maybe it is WORSE. Maybe a turned cylinder comes out looking like an ornamental candlestick. WE can't tell from here.

* order of magnitude in this case = 3.2x

oldtiffie
11-29-2010, 12:21 PM
JT.


Point being that it is NOT a case of "you gotta do it this way, or you can't do it at all".

I was at some pains to avoid saying and did not say that.

The OP or anyone else is quite at liberty to do - or not do- as they want - on their own machine/s.

All that I did was to point out the standard use and tolerances of surface plates and levels that are calibrated/scraped to a surface plate and then applied to a surface on a machine - in this case, a lathe bed.

But at the end of the day, it is the OP's lathe and the OP's option only as to what is or is not done to his lathe.

He did quantify some wear measurements that he made and posted them in this thread. I will dig them out later and will re-post them here. I made some comment on them - including test cuts - but have seen no reply.

I can and do only surmise that what the OP does or does not do to his lathe in his own good time is his business alone. It is certainly not mine.

oldtiffie
11-29-2010, 06:00 PM
Here are some pertinent, relevant and selective quotes from the OP:

http://bbs.homeshopmachinist.net/showpost.php?p=610800&postcount=1

My lathe bed has seen better days and could do with some attention. I'm a while off doing something about it but came up with a plan that I thought I'd toss out there for suggestions and comment.
I have two issues. One is that one of it's many previous owners didn't bother keeping the oiling mechanisms full and so there are visible score marks on the ways. (Someone even tried grease as a way lubricant - in the oil pump reservoir...) Measuring using one of Connelly's techniques I'm getting dips of 5 to 8 thou. The other thing is that the tailstock ways are worn enough such that the headstock and tailstock axis are not vertically co-incident. I've snapped drills discovering this.Sending the bed off for a regrind is out as that would be thousands. The plan is to make up a frame that will bolt to some pretapped holes in the side of the lathe bed and using some linear rail, make up a carriage that I can attach a tool post grinder to. I'll use that to take out the major imperfections and then use a carbide scraper and straight edge to do the last bit.
Has anyone tried this ? Anyone see any obvious holes in the plan, or ideas for improving it?

http://bbs.homeshopmachinist.net/showpost.php?p=610885&postcount=25

For those not familiar with CVA's they are a development from the Monarch 10ee round dial lathes, so are a top notch toolroom lathe. I only have room for one lathe and this is it. Fully assembled they weigh 1.5 metric tonnes. The bed is attached to a cast base, so to move it means moving around 500 to 1000kg of cast metal.
I'm not joking about the $1000's to get it ground as the rigging equipment (hired) to get it into position was $250. A truck to Melbourne (the nearest place with grinders big enough to take the whole machine) would be several hundred dollars (Melbourne is 800km (500 miles) away). I'm getting close to $1000 just in transport costs.
This lathe dates from 1957 so has seen some work. The tail stock has an oil reservoir which when I opened it up had a lump of thick grease in it. Essentially it was being slid on the bed in a dry condition. The score marks all stop at around the same place so I suspect that for a while anyway it was used for repetition work in an unlubricated state (sacrilege!).
I've looked at the Monarch posts on PM which is what has me wondering what I can do. In this case I haven't got a way that I can rely on to use as a reference so it's a matter of finding something else - hence the linear bearing bolted to a frame attached to the machine as a starting point. From memory the PM poster (beckley?) used carbide tips on a carriage to do the bulk removal but had something to work from. The other option is make up some dummy ways out of 'softer' steel and scrape those in. I have scraped slides before, so the prospect doesn't scare me. However, the ways are hardened so I don't want to spend days trying to remove 'excess material' - and we are talking thous, not mils.

http://bbs.homeshopmachinist.net/showpost.php?p=611139&postcount=73

Time is a bit precious at the moment as we have 'company coming', but I stole some time and did some (rough) measurements with a micrometer. These were done in metric and converted to the nearest thou -
In 4" jumps moving along the front parallel way (front side of the tail stock) from the head stock, deviation (wear) in thou. 0,0,4,6,5,2,1,0,1,0,0. Rear parallel way (far edge of the carriage) 2,2,3,2,1,1,0,0,0,1,0,0.
I didn't have the time to properly measure the front V way, but when I set up the bearings the manual said there should be a 1.5 thou gap between the roller and the underside of the way. Setting the roller when the carriage was at the tailstock end, I had around 5 to 8 thou when in the usual working zone on the carriage. I tried levering the tailstock quill when clamped to the bed. With moderate force close in I got 2 thou movement, with the quill 4" out I got 4 thou movement. Sliding the centres together, there is a vertical mismatch of around 1mm (40 thou). Extending the quill and the mismatch is worse.
From this I conclude that the front tailstock way has worn, as has the front carriage way. In addition, the tailstock is around 1mm down.
Scraping takes of 1/10th's, so for this sort of wear grinding is really the only way to go, it's just a question of how and where. I'll investigate the local leads provided but I spoke to a machine tool re-fitter and he said with the bed on no one in Adelaide had a machine big enough to do a proper job.

Continued next page:

oldtiffie
11-29-2010, 06:01 PM
Continued from previous page:

http://bbs.homeshopmachinist.net/showpost.php?p=611156&postcount=75

Thanks Micheal.

First of all, for those not in Australia, and as there are shops to do the work in the OP's home city of Adelaide, it is probable that the nearest cities with those facilities will be Ballarat and Melbourne in Victoria (~500 miles/800 Km) or Sydney or Newcastle in New South Wales (1,600 miles/2,000Km). So the transport costs may be high. I had a 800 pound shaper transported from Sydney recently and it cost ~ US$70 "depot-to-depot" plus US$120 for a tilt-tray truck and a fork lift with the shaper from depot to my home. The Sydney to Melbourne route is very busy and there is plenty of spare capacity at times.

I have checked the figures you gave (I will work in "thous" too on this occasion. The way wear starting at the head-stock and moving right in 4" increments are:

Front: 0,0,4,6,5,2,1,0,1,0,0.
Back:. 2,2,3,2,1,1,0,0,0,1,0,0.

The biggest deviation over any 12" or 8" or 4" on the front is 0.006"

The biggest deviation over any 12" or 8" or 4" on the rear is 0.001"

The difference between front and rear at each carriage position is:

Front:.............. 0,0,4,6,5,2,1,0,1,0,0.
Back:............... 2,2,3,2,1,1,0,0,0,1,0,0.
Difference:....... 2,2,1,4,4,1,1,0,1,1,0
Mean/average:. 1,1,3,4,3,1,1,0,0,0,0

The mean/average is important as it averages out the wear at each position and will be pretty close to what the tool rises and falls as the tool is about mid-way between the front and rear ways.

If, say the tool rose or fell 0.006" from say centre height over 8" it would increase the turned radius of a 2.000" diameter work piece to 1.00002" and its diameter to 2.00004".

If the toll were set 0.003" "off" such that it was say half above and half below the centre height over the saddle travel, the tool would 0.003" maximum from centre height, in which case the 1" radius of the same 2" diameter work-piece would only increase to +/-1.0000004" and the 2" diameter would be 2.0000009".

The difference will increase approximately linearly as the diameter decreases.

This only refers to vertical wear on the ways. It does not take account of unbalance/unequal lateral wear on the ways or any similar wear on the ways under the saddle.

If you are having significant "sizing" problems with your lathe, I'd suggest that you look further and else-where on the lathe other than the ways to at least see what the real errors and effects really are and what if anything needs to be or can be done to rectify it/them.I am not and intend not to advise or tell you what to do as that is wholly and solely your right and prerogative.

Best of luck.

http://bbs.homeshopmachinist.net/showpost.php?p=612258&postcount=114

I managed to get an indicative price for a bed re-grind from the only company I could find in town that has a grinder large enough to do the job.
To take between 5 and 10 thou off 6 surfaces is priced at between $2000 and $3000. (for those in the US, the Oz$ and the US$ are almost the same at the moment so those numbers can be taken as read). The problem is the size of the lathe bed - smaller grinders exist but the big ones are harder to find.
While it would be nice to have the grind done professionally, I certainly can't throw that sort of money around. I want to change the oil valves over the Xmas break so while I'm doing that I'll get the straight edge out, do some further assessment and have a look at the carriage running surfaces. The TS needs aligning and raising up as well to be get rid of some issues with it.
I have not been convinced by anything said so far that grinding at home is not possible (I will acknowledge difficult, exacting, time consuming etc etc) and one thing I would like to do is find a small old lathe bed and experiment a little with it - see what can be done. That won't be for a while. I will document and photograph so that if a success others can see what has been done.
Michael

http://bbs.homeshopmachinist.net/showpost.php?p=612536&postcount=130

I have a camelback (from memory) around 30" long and that's heavy enough to lift as it is. However, this should be long enough to bridge the main dips in the bed. I probably don't need that sort of precision anyway at the moment (it's been ground to microns) as in the first instance I was only intending to use feeler gauges to get a better map of the way deviations. It's one of those tools that only comes out occasionally but is used when nothing else will do the job. I bought it cheap at a junk shop where it was used as a door stop, reground it and it's fine.

Michael

http://bbs.homeshopmachinist.net/showpost.php?p=612818&postcount=146

Richard, in answer to your question "yes and no". The wear on carriage ways does not affect what I do. As someone has calculated the vertical wear I have is only changing the diameter at around the 14th decimal place.
The tailstock is another matter. As I said very early on in the thread as it currently is I get bell mouthed holes and can snap drill bits easily due to vertical misalignment. Several respondents have suggested shimming the TS but the ways are worn there too, so to fix the TS 'properly' the ways should ideally be reground (and once the machine is set up for grinding...)
It gets more complicated - via PM it has been pointed out to me from the symptoms I have the carriage is worn enough to be rubbing directly on the bed and I may also have preferential wear on one side of the carriage V way. As a result I want to do more checks when I replace the oil valves and the carriage is removed from the bed. I have already seen that I can't get a 1.5 thou feeler between the bed and carriage so there is contact.
The least I feel I must do at the moment is relieve the carriage (avoid further wear), replace the oilers (ensure lubrication is present) and shim the TS (fix the drilling issues). A professional bed grind would a good thing to add to the list but financially that's out of the question.
While I occasionally get to repair machine tools at work this activity is a hobby for me to make up for the frustration of working in a manufacturing company's quality department. (No one listens when you say that a process won't produce results to spec, but everyone holds you responsible when you stop the crap they have made going out the door). As a result the considerable effort does not concern me as much provided the end result is an improvement.

Michael

http://bbs.homeshopmachinist.net/showpost.php?p=612986&postcount=160

Those items will have to be scraped for alignment and bearing in any event, and perhaps flaked too for oil retention. It is an article of faith that wear in hardened beds will be about 20% of the wear that the saddle will suffer. Milling may be the best bet for the saddle, followed by replacement material. (Garlock, moglice, metal spray, etc). Finally scraping for bearing using the restored ways as a reference.

The traditional order of operations is top slide first, then cross slide, then saddle/bed, then bed. You cannot justify spending time on the beds without addressing the other elements of the equation too.

Greg

And so far as I can see from the posts on this thread, this is where the matter rests with the OP.

TexasTurnado
11-30-2010, 12:31 PM
I still have some items I would like to discuss, so I will start a new thread titled "Scraping Topics".

J Tiers
11-30-2010, 11:52 PM
We killed anotehr one?

I questioned the T'S alignment issue as necessarily being proof of a fault, since as otehrs pointed out as well, droopy rams are common.

We flat do NOT know what he has.......

Greg Q
12-01-2010, 12:35 AM
Another thing about all of this is the need to have a standardised series of tests and techniques to survey machines. I am going to look into posting a paraphrased version of "Testing of Machine Tools" by Schlessinger. It covers all of the standard specifications and how to determine them.

The bad news is that it also requires some good measuring tools.

Tailstock ram droop can be checked with a DTI or a co-ax, say three checks with the ram in, out and midway should be enough to check for a trend.

Greg

form_change
12-01-2010, 05:20 AM
I wouldn't say killed another one - the original question related to grinding/ resurfacing lathe beds in a home workshop. The answer seems to be (in general) that no one has.
I listed some measurements in post 73 of this thread. While quick and dirty, they showed to my satisfaction (and a couple of others that sent PM's) that I did have wear on the bed but my TS quill looked to be relatively unworn - rather that the issues were due to alignment of the quill to the lathe axis and a height difference between centres that so far resists explanation. Short term the TS will probably be shimmed and the carriage relieved to limit contact. I can tolerate the bed wear but the TS movement is harder to tolerate.

Michael

J Tiers
12-01-2010, 09:34 AM
Well, Jon Elson, who is the moderator of the Atlas/Craftsman yahoo group, DID in fact resurface his Sheldon with some form of sliding grinder.

IIRC he did other things as well, and has as much esoteric measuring equipment as Lazlo does....... So he had ways to check his work, as well as characterize the bed to begin with.

he has a website for "pico-systems", and has that process described in a piece hosted there. .

There are a couple of similar pages, his is

http://pico-systems.com/


If you fo to the machining area, and select the Sheldon lathe, it is described with photos. Unfortunately, not with much detail.

dp
12-01-2010, 12:14 PM
The bad news is that it also requires some good measuring tools.

Tailstock ram droop can be checked with a DTI or a co-ax, say three checks with the ram in, out and midway should be enough to check for a trend.

Greg

You can get a quick visual check for tail stock droop and alignment with a simple laser edge finder held in a collet in the tail stock. If you're patient you can even measure the droop this way to a high degree of accuracy.

http://littlemachineshop.com/products/product_view.php?view=classic&ProductID=2604

oldtiffie
12-01-2010, 06:15 PM
Almost but not quite Dennis.

The edge-finder needs to able to rotate so that any axial misalignment error can be identified and if required, reduced or eliminated.

I have the same lathe as you do. I also have an MT2 taper with a "live" Jacobs chuck on it (the chuck revolves on the MT2 taper - as does a live centre).

I'd just aim the "spot" at a (preferably blue) "target" about 100mm (~4") away, spin the chuck by hand and either note and accept the defined circle or use the edge-finder "X" and "Y" adjusters to reduce the "circle" to a "spot". The axis of the tail-stock MT and the edge-finder are co-incident to a quite surprising degree of accuracy. The "beam" is projected along that axis. The "spot" or "circle" "sharpness" and size are adjustable to be quite sharp and small.

I deliberately said that the beam is aligned to the TS MT2 taper axis as its quite possible that the MT taper axis is not coincident with the TS quill axis.

But.

Once the edge-finder is aligned to the TS quill axis it will soon pick up any deviation from the "tit" at the centre of a "faced-off" surface cut on the lathe (held in the chuck) as the "tit" will be coincident with the head-stock spindle axis.

The off-set of the "spot" to the "tit" will show any significant vertical or horizontal misalignment between the TS MT and/or quill axis and that of the head-stock.

Moving the quill in and out will cause any angular axial misalignment to show up as the spot moving out from and back to centre on the "tit".

That will only apply for one position of the TS on the lathe bed. It would require several such test at several different positions of the TS.

In an ideal state the spot would be on and stay on the "tit".

The limitation is the effective range of the blue ray.

http://i200.photobucket.com/albums/aa294/oldtiffie/measuring/Centring1.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/measuring/Centring2.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/measuring/Centring3.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/measuring/Centring4.jpg

oldtiffie
12-01-2010, 07:35 PM
Another thing about all of this is the need to have a standardised series of tests and techniques to survey machines. I am going to look into posting a paraphrased version of "Testing of Machine Tools" by Schlessinger. It covers all of the standard specifications and how to determine them.

The bad news is that it also requires some good measuring tools.

Tailstock ram droop can be checked with a DTI or a co-ax, say three checks with the ram in, out and midway should be enough to check for a trend.

Greg

Thanks Greg.

That will define the scope of any work required in terms of the particular machine/tool owner's requirements - as well as what may not need to be done.

That sets the basis for scope of work, skills, time and cost - ie a rational costs-benefits analysis - where all viable options and required outcomes are assessed.

But that, as you allude to, requires the tools and skills required to measure those parameters and assess the results.

No mean task - and no mean cost (or time) either.

My "touch stone" is a new (or sufficiently) "as new" machine that will do the job. Machines or tools that "will do" for what I need or want to do are quite/relatively cheap and so the existing machine under test and assessment has to be pretty good to justify any substantial work, time or cost involved.

beckley23
12-01-2010, 07:56 PM
Your tailstock is misaligned for several reasons.
The bed is worn, as evidenced by your measurements.
The TS slides are very worn, IME, mostly in the front and more so on the flat slide.
Any remedial action you take now regarding the TS, will be of questionable value.
In order to fully restore the TS alignment, the bed must be first reconditioned, either by grinding, or scraping, then you can work on the TS slides. All of the alignment corrections will be made to the slides, except one, which is the alignment to the HS spindle which is the last alignment. I think you'll find that difference you see in the alignments now, approx .040", has been greatly reduced to a more manageable level. This is all shown in the ""Wreck" Update", that I linked to earlier. It is also shown in the "Another New Toy" topic in the Monarch Forum on PM, it is a "sticky". This is also covered in Connelly's "Machine Tool Reconditioning".

Your lathe is just as much a "Wreck" as mine was, except I don't think you have a lathe that's been rolled on its back.
I assume from your description that the inside flat way is worn and scored a short distance from the headstock. Since the CVA is a copy, for intents and purposes, of the EE, I'm also going to assume that they are extremely similar in the details of their clearances. On the EE, in fact all Monarch lathes that I'm familiar with, the saddle has a "false" slide for the inside flat way. According to Monarch the clearance between the saddle and the "false" slide is approx .004", or more. It does not bear on the ways, and is not meant to, but over time as the saddle wears this clearance is reduced. In cases of lack of lubrication from oil pump failure in the apron, the saddle wears to the point, that the "false" inside flat slide is bearing. If this situation goes on for any length of time, you will see the results that you see. Monarch's solution is to remove the saddle, and machine more clearance into the "false" slide. I tried that on the Series 60, and the saddle was considerably harder to move when reassembled. It was then, after some test cuts, that I decided to correct the situation by reconditioning the inside face of the front V way and applying Multifil 426 to the saddle slides.
It is not an easy fix, but it can be done. Both the "Wreck" and the Series 60 had this problem, and the solutions have been described.
Harry

PeteF
12-01-2010, 08:43 PM
Well, Jon Elson, who is the moderator of the Atlas/Craftsman yahoo group, DID in fact resurface his Sheldon with some form of sliding grinder.

IIRC he did other things as well, and has as much esoteric measuring equipment as Lazlo does....... So he had ways to check his work, as well as characterize the bed to begin with.

he has a website for "pico-systems", and has that process described in a piece hosted there. .

There are a couple of similar pages, his is

http://pico-systems.com/


If you fo to the machining area, and select the Sheldon lathe, it is described with photos. Unfortunately, not with much detail.

Did he? According to his site he tried grinding it himself with reference to the the "good" TS ways, and and not only did it not work, it actually made things worse! He says he resorted to using oilstones and hand rubbing the high spots down! Given that, as I understand it, the OP doesn't have ANY good ways to reference from, his situation is even worse than that described above. There is a reason people are suggesting either have it commercially ground, scrape it, or leave it alone.

lazlo
12-01-2010, 09:20 PM
Another thing about all of this is the need to have a standardised series of tests and techniques to survey machines. I am going to look into posting a paraphrased version of "Testing of Machine Tools" by Schlessinger. It covers all of the standard specifications and how to determine them.

Connelly's Machine Tool Reconditioning goes step-by-step through the Schlessinger Limits for each machine type (lathe, mill, surface grinder), and shows not only how to measure each limit, but how to scrape it back into aligment.

oldtiffie
12-01-2010, 09:23 PM
Well said Pete.

That is the "nitty gritty", bottom line and perhaps end-game so far as the OP is concerned as its his lathe, time and money and his right to decide what suits him on the day.

Getting in "too deep" when you can see it happening and being able to get out or back out is bad enough, but getting so far in that there is no reasonable outcome or not knowing how or when to "call it quits" is even worse - but all too easily done.

I think that the OP has been very sensible about it as he has a lathe that he can use until he has time to think about it and what and when to do whatever he decides to do.

PeteF
12-01-2010, 10:12 PM
Don't get me wrong Tiff, I've never done anything like this myself and think at face value the OP's original concept of creating "artificial" ways on which a temporary grinding carriage could slide has, in theory, a lot of merit. Indeed I admire his thinking outside the traditional box.

However from a practical perspective the difficulty in making the temporary ways that length, scraped perfectly flat AND that didn't sag as the carriage moved along them AND had a very rigid carriage AND used a suitable precision spindle and so on and so on, I simply can't see the theory translating successfully into practice. Even a very small surface grinder is a relatively beefy bit of kit, for good reason, never mind something with the capacity to grind a bed as mentioned here.

gnm109
12-01-2010, 10:31 PM
Don't get me wrong Tiff, I've never done anything like this myself and think at face value the OP's original concept of creating "artificial" ways on which a temporary grinding carriage could slide has, in theory, a lot of merit. Indeed I admire his thinking outside the traditional box.

However from a practical perspective the difficulty in making the temporary ways that length, scraped perfectly flat AND that didn't sag as the carriage moved along them AND had a very rigid carriage AND used a suitable precision spindle and so on and so on, I simply can't see the theory translating successfully into practice. Even a very small surface grinder is a relatively beefy bit of kit, for good reason, never mind something with the capacity to grind a bed as mentioned here.


You've summed it up nicely. Using a carriage to grind a lathe bed is one of those ideas that, in theory, could work perfectly. The devil is in the details, however.

I also was wondering about wear on the grinding wheel as it travels back and forth....the slightest amount from one side to the other would translate into a possibly unrecoverable error.

It's so far out of my league that I probably shouldn't even comment, except to say that it sounds terribly difficult. There's a reason why a professional bed regrinding shop gets the money they do for that sort of work.

JMO.

oldtiffie
12-02-2010, 12:02 AM
Don't get me wrong Tiff, I've never done anything like this myself and think at face value the OP's original concept of creating "artificial" ways on which a temporary grinding carriage could slide has, in theory, a lot of merit. Indeed I admire his thinking outside the traditional box.

However from a practical perspective the difficulty in making the temporary ways that length, scraped perfectly flat AND that didn't sag as the carriage moved along them AND had a very rigid carriage AND used a suitable precision spindle and so on and so on, I simply can't see the theory translating successfully into practice. Even a very small surface grinder is a relatively beefy bit of kit, for good reason, never mind something with the capacity to grind a bed as mentioned here.

No offense taken Pete - at all - as I was very pleased to see that post of yours.

Whatever "way" the OP uses to grind the lathe bed, it not only has to be very "stiff" vertically but even "stiffer" laterally so far as deflection being minimised during the grinding process goes. The set up relative to the head-stock and the lathe bed is another matter that needs to be accurate and is pretty critical as regards accuracy.

Anything taken off "too much" may not be recoverable in practical terms.

If there is any vertical deflection it can in large part not really upset a parallel turned piece if it is only say no more than say 0.004" - but preferably no more than 0.002".

A "drop" of say 0.004" from say 0.000" will only cause an increase in the radius of a 1" test piece to increase from 0.50000" to 0.500016" - say about 0.16 of a "tenth".

That same "drop" of say 0.004" from say 0.000" will only cause an increase in the radius of a 1/2" test piece to increase from 0.250000" to 0.250032" - say about 0.32 of a "tenth".

A "drop" of say 0.004" from say 0.000" will only cause an increase in the radius of a 1/4" test piece to increase from 0.12500" to 0.125064" - say about 0.64 of a "tenth".

But if that 0.004" were to be "split" so that 0.002" was above centre and 0.002" below it over the length of the test cut the differences in radii and diameters would be negligible.

But on the other hand, any lateral error in the "vee" way/s will cause the carriage to move that amount which will increase or decrease the test piece radius directly.

That is to say that no matter what the diameter a say 0.004" lateral "error" in the say/s will cause the tool to remove 0.004" from the radius and 0.008" from the diameter no matter what the diameter.

This, in large part, explains why so many lathes with "lots" of "vee-way" (and under-side of the carriage too) are as accurate as they are as most of the wear is vertical and not lateral (as it usually is in a milling machine dove-tail).

If my lathe got to the point where I seriously needed to contemplate having it ground, I'd seriously have to contemplate doing the saddle way/s (and building them up) and the cross-slide and top-slide too - and potentially a LOT more besides, it would have to be a seriously compelling case or else that lathe would be off to scrap and a new one bought in.

I could buy a seriously good Chinese lathe (new) for some of the figures the OP quoted just for a bed grind.

This sort of work requires a spare lathe as well as a lot of room to strip, clean, lay-out and re-assemble that carriage at least.

But I do not want to tell the OP what to do.

He is doing very well taking his time and assessing his issues and options.

Greg Q
12-02-2010, 03:29 AM
That's a neat trick with the laser...and as you point out once you achieve the minimum circle diameter you are left with whatever runout your chuck presents. I still don't see how it relates to the spindle axis though.

Also, mounting the laser in the tailstock bore will indicate droop as the ram is run in and out. It will not show if the ram is parallel to the lathe bed (which we weren't discussing anyway)

WRT your last point Tiffie, in my case there are intangibles that override rational behaviour. This hobby allows me to afford some pretty remarkable machines which you can no longer buy at any price. Repairing them is the price you pay, and often the rewards are greater than the labour involved. Purely from a zen perspective if nothing else.

The process of restoring a toolroom machine seems to me to be exactly the same as fixing up an old bike or muscle car.

.RC.
12-02-2010, 03:47 AM
I could buy a seriously good Chinese lathe (new) for some of the figures the OP quoted just for a bed grind.




errr no... Seriously good chinese lathes are not imported into this country because they would be that expensive no one would buy them...

oldtiffie
12-02-2010, 04:59 AM
Originally Posted by oldtiffie
I could buy a seriously good Chinese lathe (new) for some of the figures the OP quoted just for a bed grind.

errr no... Seriously good chinese lathes are not imported into this country because they would be that expensive no one would buy them...

Err yes.

The cost for the bed grind to the OP "all up" with transport plus intangibles - and contingencies - etc. would not have left much change from AU$4,000.

This lathe is not bad at all and would suit me fine - AU$4,350 and I'd expect to get it at under AU$4,000.

https://www.machineryhouse.com.au/images/105721.jpeg

https://www.machineryhouse.com.au/Products?stockCode=L682D

For my requirements, that is a seriously good lathe - with a good warranty and parts support.

Transport is no problem as it is only about 40Km from home - not more than an hour with the trailer on. And at ~600Kg (say 1,300 pounds) is within my 1 tonne hoist capacity.

If I wanted it delivered on a truck with a fork-lift it would probably cost me about $150.

Wheel the old lathe out, install the new lathe, dismantle and disable all component parts of the old lathe and take it to the local municipal recycle depot - no cost and only 10 Km away.

Up and running in under a day with no real disruption to the shop at all.

.RC.
12-02-2010, 05:47 AM
"Seriously good" is in the eye of the beholder...

oldtiffie
12-02-2010, 05:51 AM
Nope.

I'm a realist - not a romantic.

In my case and for my purposes that lathe is seriously good and fit for purpose.

PeteF
12-02-2010, 06:08 AM
That's a neat trick with the laser...and as you point out once you achieve the minimum circle diameter you are left with whatever runout your chuck presents. I still don't see how it relates to the spindle axis though.

Also, mounting the laser in the tailstock bore will indicate droop as the ram is run in and out. It will not show if the ram is parallel to the lathe bed (which we weren't discussing anyway)

Greg, if a centre was placed in the spindle bore and the laser described an equal circle around it as the laser was rotated (or if it had absolutely no runout, hit the centre), wouldn't it then indicate that at least at that point on the bed the TS bore and bed (hence hopefully HS spindle) were all linear? Of course at that point it could be a coincidence of the wear in the TS base, any droop, and wear in the ways were cancelling each other out, but that would become evident at further points on the bed. With regards the TS "droop", I would think that unlike measuring with a DTI, winding the ram in and out won't indicate any difference on the laser. Assuming everything runs in and out linearly, winding the ram out simply moves the laser closer to the target, but as it's moving along the same line I would think it won't make any difference to the circle (or, ideally, spot) produced by the laser?

Pete

Edit: I guess I should have said that I'm presuming the very basics of ensuring the TS and HS are at the same height were done before any further investigation. After all there's no point in going any further if they're not at the same height. Tiff where did you get your laser from, Little Machine Shop? I've seen a "home brew" effort in some mags but think the LMS laser is a bit pricey for what it is. As you pointed out, they can be calibrated by rotating so no monumental accuracy seems to be involved in their initial construction. I seem to recall a very similar idea being used with a web-cam camera some years back.

.RC.
12-02-2010, 06:20 AM
In my case and for my purposes

That is what I mean by "in the eye of the beholder"

In the grand scheme of things it is not a "seriously good lathe"

A new $80 000 10EE from Monarch is a "seriously good lathe" A Hardinge HLV is a seriously good lathe... As is a Weiler or Schaublin.. All top of the line and very very expensive..

It is a bit like what constitutes a "big lathe".. If you use little 12" swing machines all the time and you see a 21" swing machine you think that is a big lathe... While reality is a 21" swing or even a 36" swing machine is not a big machine nor really even a medium size machine... They are toys compared to the really big monsters with 20ft swings..

Greg Q
12-02-2010, 06:21 AM
Quoting Pete F:

"Greg, if a centre was placed in the spindle bore and the laser described an equal circle around it as the laser was rotated (or if it had absolutely no runout, hit the centre), wouldn't it then indicate that at least at that point on the bed the TS bore and bed (hence hopefully HS spindle) were all linear? Of course at that point it could be a coincidence of the wear in the TS base, any droop, and wear in the ways were cancelling each other out, but that would become evident at further points on the bed. With regards the TS "droop", I would think that unlike measuring with a DTI, winding the ram in and out won't indicate any difference on the laser. Assuming everything runs in and out linearly, winding the ram out simply moves the laser closer to the target, but as it's moving along the same line I would think it won't make any difference to the circle (or, ideally, spot) produced by the laser?"

Yes, it would. Except that the dimension of the laser spot is much larger than the sensitivity of our conventional instruments. (Blake, DTI, Centricator, what-have-you)

The laser if mounted in the tailstock ram only shows the axis of same. If that axis is inclined relative to the ways (because of a worn base) then that will become apparent when you try to target the HS spindle axis. If, however, the ram droops with extension owing to a worn TS bore, then the laser spot should fall with ram extension. The subsequent repair schemes are of course different, neither of them trivial.

Tailstocks wear at the front because of the way they are shoved along the ways...the operator pushes at the back, causing the tailstock to grind into the ways (and swarf) at the front of the base. The typical absence of wipers or lube points on tailstocks aggravates the wear.

PeteF
12-02-2010, 06:33 AM
Yes, it would. Except that the dimension of the laser spot is much larger than the sensitivity of our conventional instruments. (Blake, DTI, Centricator, what-have-you)

The laser if mounted in the tailstock ram only shows the axis of same. If that axis is inclined relative to the ways (because of a worn base) then that will become apparent when you try to target the HS spindle axis. If, however, the ram droops with extension owing to a worn TS bore, then the laser spot should fall with ram extension. The subsequent repair schemes are of course different, neither of them trivial.

Indeed. I had in my mind to use it in conjunction with more traditional measuring techniques. I thought it could be a very useful way to get a TS aligned accurately if it was done at the far end of the bed where there is typically not a lot of wear. As you said, the laser dot itself isn't especially small, but I would think over the length of the bed the angular differences in the planes would be amplified by the relatively large distance between the laser and the target, thereby making it actually quite a useful tool. Up close to the HS on the other hand I'd think it just about next to useless.

Edit: I guess I'm rather selfishly thinking of my own particular situation where the TS on my little lathe was both worn and from a completely different machine. While I was able to shim it up to get it quite accurately on centre, the for/aft "tilt" I found a lot more difficult to really accurately measure, hence correct. While the only time it probably really matters is, say, when reaming, it would still be nice to get it spot on. In this particular instance I thought the laser method showed promise to help identify any tendency for the tailstock to point slightly up or down. You don't think the laser would be accurate enough even at around 1 m arm?

oldtiffie
12-02-2010, 07:10 AM
Originally Posted by oldtiffie

In my case and for my purposes
That is what I mean by "in the eye of the beholder"

In the grand scheme of things it is not a "seriously good lathe"

A new $80 000 10EE from Monarch is a "seriously good lathe" A Hardinge HLV is a seriously good lathe... As is a Weiler or Schaublin.. All top of the line and very very expensive..

It is a bit like what constitutes a "big lathe".. If you use little 12" swing machines all the time and you see a 21" swing machine you think that is a big lathe... While reality is a 21" swing or even a 36" swing machine is not a big machine nor really even a medium size machine... They are toys compared to the really big monsters with 20ft swings..

Nope - again.

I said what I meant and meant what I said.

The new lathe I mentioned is quite satisfactory for my purpose - "as is". I am not so sure about the OP's clone 10EE in its "as is" state.

As the $4,000 lathe suits my purposes, why should I waste $80,000 on a new or re-conditioned (by the factory) "as new" 10EE?

Not-with-standing that he 10EE won't fit into my shop and I don't have the power to run it.

I've run Macson (OZ), DSG (the best in the range in a laboratory) as well as "Ward" and "Lang" and other large and small as well as Schaublin lathes and mills in a tool-room, Cincinnati and other grinders etc. which while nice and necessary in their place then don't suit me here so self-evidently they fall outside my current definition of and requirement for "seriously good". They would, in my case, be an impediment and a serious waste of a lot of money.

I have no sentimental or emotional attachment or regard for any machine now-a-days as its only something that does the job I want it to do (in which case it stays or gets bought) and if it doesn't, it gets destroyed and disposed of - or not bought in the first place.

That $76,000 difference can do a lot better than being wasted on a machine I neither want nor have any use for.

If others have a perceive "need" and a lazy $80K to spend on - good for them. Its their decision and their money.

My point is that for the lathe at $4K ready to go is a lot cheaper than doing all works necessary to fully restore the OP's lathe to "10EE" as ("near"?) new condition. But I'd guess that the "re-grind" only option that the OP seems to have in mind will not be all the more or less than the lathe I have in mind - for what I want and need to do.

But that's for the OP to decide - not me or anyone else either - as it should be.

Greg Q
12-02-2010, 07:39 AM
Edit: I guess I'm rather selfishly thinking of my own particular situation where the TS on my little lathe was both worn and from a completely different machine. While I was able to shim it up to get it quite accurately on centre, the for/aft "tilt" I found a lot more difficult to really accurately measure, hence correct. While the only time it probably really matters is, say, when reaming, it would still be nice to get it spot on. In this particular instance I thought the laser method showed promise to help identify any tendency for the tailstock to point slightly up or down. You don't think the laser would be accurate enough even at around 1 m arm?

Some quick "back of the iphone" math gives me around 5 spot dimension for 1 arc-second. I only have a cheap 1st generation laser level here...the spot looks like it might be at least 100, which means...20 arc seconds or so. Sounds like it might be good enough, depending*

*when doesn't it depend?

Greg Q
12-02-2010, 07:43 AM
Nope - again.

I said what I meant and meant what I said.

The new lathe I mentioned is quite satisfactory for my purpose - "as is". I am not so sure about the OP's clone 10EE in its "as is" state.

As the $4,000 lathe suits my purposes, why should I waste $80,000 on a new or re-conditioned (by the factory) "as new" 10EE?

Not-with-standing that he 10EE won't fit into my shop and I don't have the power to run it.

I've run Macson (OZ), DSG (the best in the range in a laboratory) as well as "Ward" and "Lang" and other large and small as well as Schaublin lathes and mills in a tool-room, Cincinnati and other grinders etc. which while nice and necessary in their place then don't suit me here so self-evidently they fall outside my current definition of and requirement for "seriously good". They would, in my case, be an impediment and a serious waste of a lot of money.

I have no sentimental or emotional attachment or regard for any machine now-a-days as its only something that does the job I want it to do (in which case it stays or gets bought) and if it doesn't, it gets destroyed and disposed of - or not bought in the first place.

That $76,000 difference can do a lot better than being wasted on a machine I neither want nor have any use for.

If others have a perceive "need" and a lazy $80K to spend on - good for them. Its their decision and their money.

My point is that for the lathe at $4K ready to go is a lot cheaper than doing all works necessary to fully restore the OP's lathe to "10EE" as ("near"?) new condition. But I'd guess that the "re-grind" only option that the OP seems to have in mind will not be all the more or less than the lathe I have in mind - for what I want and need to do.

But that's for the OP to decide - not me or anyone else either - as it should be.

I've seen you write similar before, and I wonder if your attitude springs from your long career on the machines? There are plenty of amateurs doing what I do for a living, and their vehicles are much nicer than what I'd buy for myself if I had to do it in my spare time. I have operated some horrific pieces of crap professionally, and don't mind them. In my private life however, I can't abide by cheap ****. That's why I do without a lot of things I guess.

vpt
12-02-2010, 08:53 AM
So when is the grinding going to start? I keep checking the thread for pictures to see what the OP came up with and how it is going.

oldtiffie
12-02-2010, 09:09 AM
Greg.

Thanks.

I appreciate and respect your way of doing things.

I am a pragmatist and a realist and certainly not a romantic as regards tools etc. I have no real ego problems with machines either.

I set my requirements at 5 on a scale of 10. If what I see makes 5>7 its doing pretty well. Over 8 as does under 5 needs a good look at in most cases but unless it has a compelling case it is rejected.

The OP's lathe is an object lesson in the travails of buying and/or having a really worn "good" machine.

As I've said else-where, I have no issues but lots of respect for those that "make do" or (intend to?) "do up" an old or worn "quality" or "name" machine or tool.

I, as I presume do most here, have limited funds that have to "make do". I pay cash for everything. If I haven't go the spare cash I just simply go without and wait until I have that cash.

I detest credit.

I like to know that what I have in my account is mine to piss up against the wall if I choose without it being ear-marked as payment of a loan or for payment to someone else.

Actually, some of the gear I have is remarkably good as regards accuracy, state and serviceability. I do quite well with stuff that others may regard as sub-standard or "junk". Perhaps it is - but it and I get the job done.

I write off anything I buy to zero as it will never be realised and if it were valued it is only a best guess as to what someone might pay at possibly not much more than "Fire" or "Estate" sale values.

I find that I don't often have to wait to save funds for what I want to buy for the shop as the initial "surge" has abated over time to now being a more reasonable (sedate?) "pace".

I've had my fingers burned often enough in the past and just as often by myself as others. I've learned my lessons over time and make a good effort to match my purchases with my needs (as opposed to my "wants") and resources.

I do "lash out" once in a while - but not too often.

I am not a fan of "hogging" and thrashing machines. I prefer to use them at no more than just below or less than their normal limits on small work so many smaller and lighter - and less expensive - machines meet most of my needs.

But I don't begrudge or belittle others who may differ as I respect their rights to do as they will.

J Tiers
12-02-2010, 09:54 AM
To a certain degree, the question can come down to what you get for the money.

IF, and that is in this case a rather large "IF", an amount equivalent to the cost of a reasonable chinese machine can be spent and the result will be the restoration to something similar to original accuracy of a very good lathe, that can be worth while.

This is NOT SENTIMENTALITY.

it is a business decision. Return on investment.

If I buy a Chevrolet sedan, at retail cost, in a few years I can sell it for whatever residual price it may bring, which is likely to be low, somewhat over scrap value, in the range of 15% of new cost.

If I ALREADY HAVE a used and somewhat abused Lamborghini, and restore it properly to usable + condition, I can expect to be able to sell it later for at least what I paid for it, probably including restoration costs and a decent premium.

The situation here is similar. You offer the choice of an investment in either:
a) a usable chinese machine, quality somewhere between a Trabant and a Chevrolet
or b) an investment in restoring a valuable classic, call it a Lamborghini

Your choice is the Trabant. or possibly using as-is, I can't tell which you mean.

if your SOLE consideration is something that spins a workpiece when you want that a few times a year, then it isn't even worth restoration, let alone buying a new machine. it will work fine as-is. Buying a new machine is do-able, but does not buy you as much for the money. "Trabants" from china are pretty numerous and when they start to come up for sale as HSMs die off, they won't bring much. The few I have seen usually sold at large discounts.

Accepting that the choice is restore vs buy a different machine...... and that using as-is is not on the table.... If you want to use a good machine, AND think that if you sell the machine later, you prefer not to lose money on the deal, then it is probably a superior business decision to restore the better machine. This is opposed to selling it as-is at a probable loss, and investing in a much lower quality machine which will not have much residual value.

Sentiment be hanged.

macona
12-02-2010, 02:54 PM
Nope - again.

I said what I meant and meant what I said.

The new lathe I mentioned is quite satisfactory for my purpose - "as is". I am not so sure about the OP's clone 10EE in its "as is" state.

As the $4,000 lathe suits my purposes, why should I waste $80,000 on a new or re-conditioned (by the factory) "as new" 10EE?



FWIW, they are actually new now, and the price went up to $100k. A reman is about 60k. From what I understand they are even having 30 inch beds cast again.

form_change
12-02-2010, 04:34 PM
VPT and others waiting for some action - don't hold your breathe. As I said in I think my first post, It will be a while before I do anything as even after I have a workable plan there will be extensive preparation to be done before any wheel touches metal.
Once I have something worth showing I'll post results for people to see in a new thread.

Meanwhile my take on why I bought an old lathe. I had a 7x20 lathe but found for my TAD volunteer work (Technical Aid to the Disabled) that something larger would be more useful. I had the choice between new Chinese ($3 to 4k) or something second hand (dealer prices $4 to $8k). I also looked on eBay and saw someone selling a CVA for $6k. Intrigued, I did some research and based on the lathes.co.uk page and snippets on the 'net from Tim Leech and John Stevenson* decided that if I could get one at a reasonable price it would be a good project machine as well as having the capabilities that I wanted (secondhand Monarchs and DSG's were also considered for restoration). A strong consideration was that new attracts a lot of attention from the other half. Something that looks old and battered can appear in the shed far more readily.
I paid $1.5k for it (plus transport) and after fixing loads of the usual sorts of problems (parts missing, electrics non functioning, replacing bearings and so on) I have a functioning lathe. The bed (and it's sliding components) is the last major part of the project. Once that's done I hope it will last another 50 years.

Michael
*These two guys have been very helpful but I think I may have put John's nose out of joint - ever since learning that the lathe could cut 19tpi and had taper turning fitted (neither of these features his CVA has) I haven't had a response to any of my emails. If I'm ever in Nottingham I may have to smooth the waters with a pint of something...

PeteF
12-02-2010, 04:38 PM
Some quick "back of the iphone" math gives me around 5 spot dimension for 1 arc-second. I only have a cheap 1st generation laser level here...the spot looks like it might be at least 100, which means...20 arc seconds or so. Sounds like it might be good enough, depending*

*when doesn't it depend?

Ok, that may be worth pursuing then, time for a cheap-arse laser pointer perhaps ;) The problem I was encountering when trying to accurately measure the overall dip of the TS quill is that it required me to measure along it, and it's not especially long, by moving the indicator/TS along the bed. Again one of those situations that works great in theory but proved quite difficult to accurately do in practice for various reasons.

Anyway, I'll let you guys continue the old argument of restoring versus buying new. Personally I can't think of too many situations where restoring makes economic sense (if labour is included), but thank goodness a heck of a lot of people don't think purely along those lines ...

.... I'm one of those suckers ;)