Scraper People question

[beckley23]

I don't quite understand the comments about MTR. Connelly wrote the book for a newbie, when there wasn't anything else available, a situation that remains so to this day, and will most likely remain so. The book is laid out in a logical order, and thoroughly explained; and yes, the language is a bit archiac, and it is definitely not a page turner. I will also agree that some of methods and/or prohibitions are questionable, ie: the prohibition on shimming. The fact still remains that there is nothing else available.
I wouldn't recommend the way I did the beds on my last 4 lathes, the first one I didn't write about, to a beginner. It really takes a great deal of care to employ that method. If you consider the logistics and weights involved, I think you will agree that it was easier than the recommended procedure in MTR.
Regarding the TS's. I scraped the V and flat slides to obtain the alignments. The fact that I scraped the flat way, afterwards, is the result of an error on my part for not checking the spindle alignment first, but mostly the result of how Monarch manufactured their tailstocks.In any event, either the bottom of the top, or the top of the bottom would have had to been scraped, it was a matter of the lesser of two evils. If you take a look at Monarch's design, you will understand. Also the transverse way squareness is not big concern with Monarch, at least that's my conclusion. I've gotten burned there twice.

Steve- You will do just fine, the only hard part is the actual scraping process. It seems like your TS just needs attention on the slides. I'll bet that you don't have as much scraping as your indicator readings show.
Harry

[J Tiers]

maybe there is another question.........

There is less material involved in scraping the flat and V, assuming he is right and the top half of the T/S is correctly parallel to the ram bore.

But, the process of scraping the V and flat is much more fussy, since you must scrape to several constraints at once. The V-way must keep the ram bore parallel front to back, it must bring the ram bore parallel vertically (correcting the sag), it must continue to fit the ways, and the flat way must match the V.

The V and flat are, no doubt, worn. A "real" rebuilder no doubt would scrape them to bring the 0.008 misalignment back "in".

But from a pure consideration of the skill level needed and overall hassle, it seems that the simpler way is, however, to scrape the TOP of the lower half. That requires only making it flat (checked against the top half) and bringing down the correct area in order to restore the alignment.

The spotting is simpler also, since it needs only a contact/support fit, bluing maybe 5 spots per inch.

This depends on the V and Flat actually bluing correctly against the bed as they are.

Even that is a question, since the tailstock wear suggests that there may be wear on the bed. Depending on the area the T/S was used in most, it might not be possible to make the T/S fit its ways everywhere even if the V and Flat were scraped.

As for Connoley being dictatorial...... There are many places where he suggests that a choice can be made, depending on preference and condition of the machine. It is not a "one size fits all" approach. It IS however, written with the idea that the work will be done "correctly", everything in proper order, and the machine to be as good or better than new when finished.

[MuellerNick]

I didn't want to say that MTR is a bad. Book. Au contraire, it is quite good if you can live with the writing style and lack of explanation of the whys.

Re shimming:
It's not the best solution, but the cheapest.

If you can do without it, avoid it. If you have to use it, use it all over the surface, and not just a small strip on the left and one on the right (even with different heights). That's a cheap job!

Scraped fitting surfaces do have a dynamic property, they damp much better than one that was milled or ground or planed. The factor is at least 3 times better (out of my head). The little cavities and channels are filled with oil (you apply before assembling). They act like small hydraulic dampers sucking oil through narrow orifices etc.
So the aim is to get as much contact area (and not waste area with small shimming strips) and to scrape it.


Nick

[beckley23]

JT,
Over the years I have looked for easier ways to scrape in a piece. There is no way one is going to get out of scraping the V and flat slides/ways into alignment. You're right it is fussy work, but that is a mental problem. You're always asking the question of which faces of the V to scrape, there's always going to be at least one section, and often 2 sections on opposite sides at each end. It gets real confusing when you flip the piece over, of which face gets scraped. That's why I mark the faces that get scraped.
With regard to the bed way condition, that is a judgement call. On the Series 60 in "Another New Toy", the inside ways were thoroughly checked, and there was/is bed wear right where you would expect it. The wear was so minimal, mostly on the flat way where the carriage was actually making contact from the wear on the inside face of the front V way, that I could see no significant benefit to scrape it. Steve is going to have check his bed out as best as possible and make a decision. The "Wreck" on the other hand was a totally different story, and should have been scrapped, but it's a 30" EE, and sometimes I let things get the better of my judgement.
BTW, if you think the TS base is hard, take a look at the saddle, there's the challenge.

Nick,
I have to differ with you on the lack of explanations, but agree on the rest. The shims sure do make life easy, though.
Harry

[J Tiers]

JT,
Over the years I have looked for easier ways to scrape in a piece. There is no way one is going to get out of scraping the V and flat slides/ways into alignment. You're right it is fussy work, but that is a mental problem.

BTW, if you think the TS base is hard, take a look at the saddle, there's the challenge.


Harry

"No way"? Too strong.

Use "possibly"..... it is a question of what HE wants to do..... Alignment? what alignment?

if teh base blues to the ways, it is good in itself. You want to touch up, go for it.

if the base has its cross-key misaligning the top, that's a problem.

other than that, the base controls NO alignment if the top is already right, and you make the base upper surface repeat that correct alignment.

Now, if the base is worn off and will TURN the top part, due to the cross-key, OK then you scrape for 4 alignments at once and you do it on the V and flat.

There is a good chance that IS the case, but no guarantee of it.

Saddle?

V and flat is not so bad. Two V is bad. Like Southbend

[beckley23]

JT,
You know than I do, do it your way and I'll do it mine.
Harry

[J Tiers]

JT,
You know than I do, do it your way and I'll do it mine.
Harry

?????????????????????????

I do NOT know "more" than you do (I do know you forgot a word). So don't tell me I said so.

If there is a reason why the v and flat should be scraped instead, OK. But it seems that would be making more trouble with no better result. it seems that the top could be scraped down to bring the upper half into correct alignment, with a lot less hassle, assuming the base V and flat are OK and not throwing the top in a twist.

If you have a good reason why that won't work, let us ALL know it.

[beckley23]

Look at the requirements of the TS alignment I listed above. In the end those are the only tests needed for alignment. Let's assume that the bottom of the top, and the top of bottom have been mated for the reasons that Nick pointed out, mainly that they bear properly, incidently this should be checked, I had one top whose bottom wasn't flat and had to be scraped. There still remains the flat and V slides. These surfaces are worn, and are going to have to be scraped such the spindle test bar checks are good. Why on earth do you want to do more scraping when it's not needed.
When you scrape the V slide you're going to have scrape opposite sides until you get the test bar straight, and at some point you are going to have to start scraping the flat, and eventually you will have to start scraping for bearing area.
There are a couple of other "requirements" for levelness of the top of the bottom. I can understand the transverse requirement to a certain degree, for those of you who offset the top for taper turning, but I have a real hard time seeing the need for longitudinal level of the top of the bottom. If it's there great, but I'm not going to worry if it isn't.
I did quite a bit useless scraping on the Series 60 TS bottom, and these are the lessons I learned.
Harry

[J Tiers]

OK. Questions

The OP in this case thinks he does need to scrape the V and flat. So for him, no problem. If you have to scrape them, you may as well do as much as possible in alignments there. I totally agree.

However, let's take an example. Assume you take over a job, and someone has started by scraping the V and flat correctly to the ways. Other alignments are good, but the ram is still drooping, while the top and bottom are in good contact, and underside of top is aligned with the ram.

On the face of it, everything is correct except the T/S base. On the base, the V and flat are not aligned with the top, causing the droop, which is the basic problem. All surfaces are OK for contact etc.

But you still need to fix the droop.

Is there a good reason in this case to choose to re-scrape the V and flat, and NOT the top?

[beckley23]

OK, let's see if I can explain this.

I'm assuming the bed is in good condition. The TS slides wear in generally the same manner, the ram, quill, or spindle is pointing down and either to the front or the back, I've never seen one that is straight. So what you have is a lot of wear on the front of the slides, and less in the rear, and the V will be more worn than the flat, IME. It's real easy to scrape for the vertical alignment, but you have to scrape the V and flat slides straight down. At this point all you have done is correct the vertical alignment, in theory, but you really don't know, because you haven't corrected for the horizontal alignment, imagine doing the test bar checks at this point. For this correction you can't scrape the transverse way or slide because of the fit requirement, so you're left with the correction being made on the V slide. Now you have to decide where and which part of the inner and outer face(s) to scrape. Imagine looking straight down on the TS, which way do you have to rotate the TS to obtain horizontal alignment, and that will tell you which sections of the V slide to scrape. At the same time you will also have to scrape the flat slide straight down, to compensate for what comes off the V slide.
While all this scraping is going on, you are also doing the test bar checks periodically, to monitor progress.
Given the parameters you gave, the top and bottom planes of the bottom should be parallel, but don't alarmed if it isn't. The only things that matters are the test bar checks.
The next problem is getting the headstock and tailstock centers aligned using a test bar, or some other method, and for that I'll use shim stock.
Hope this helps.
Harry

[doctor demo]

OK. Questions
The OP in this case thinks he does need to scrape the V and flat. So for him, no problem. If you have to scrape them, you may as well do as much as possible in alignments there. I totally agree.
But you still need to fix the droop.

Let Me jump back in , I have not done any thing yet. I walked into My garage and found a stream of water running from the hot water heater out to the door. So running around gathering plumbing parts and working on it ,took away from tail stock work.
So today I blued up the end of the lathe bed and set the t.s. bottom on it and it wobbles so I know I need to do significant work on it. If I hold it down against the bed I can slide a .010 feeler under the front flat . If I put a ground round test bar in the v it is making decent contact ,but there is a distinct ridge at the bottom of the v. I'm actually thinking of setting it up on the surface grinder on a pair of dowel pins for the V and a pair of parallels for the flat way, indicate in the transverse key and grind the top flat. Then flip it over set that flat surface on the parallels on the mill and mill the flat way slide flat then change to a V end mill and clean up the V slide to get a starting point for the scraping. I don't want to scrape 9thou by hand.

Who ever had this really had it all screwed up , when I split top from bottom I knew there were shims in it . Now that I look closer it was cardboard sandwiched between brass shims. That probably has a lot to do with the twist in the base.

Steve

[J Tiers]

mr B....

OK, you assume (no doubt correctly) that the wear is such that you have to scrape anyway. I understand the scraping for the vertical, horizontal, etc, I have actually done that. It is a pain, IIRC there are 4 different things to get right. (flatness, vertical "aim", Horizontal "aim", and flat to be in correct plane relative to V.

I guess my question was that if the ONLY problem is droop, NO aim-off error, etc, the top half of T/S has its bottom aligned with ram, and all surfaces are in contact and already scraped to at least "local alignment".

Maybe the guy who started it is out sick for a month, whatever, and you have to finish the job. he already got everything scraped-in, but he messed up and it still droops.

In THAT case, which does not REQUIRE attention to any particular surface other than to fix the droop....

is there a good practical reason to CHOOSE to scrape the V and flat, versus the top of the base, to correct the droop?

Remember, all surfaces and fits are OK, and JUST the droop needs attention.

[MuellerNick]

An alternative to using shims is to cast a new higher surface with "Multimetall Stahl" or DWH. Both come from the maker of Moglice.
"Multimetall Stahl" can be scraped with good results, DWH not. Both are steel filled resins. DWH has tiny balls inside that make it impossible to scrape.
For both, you need to mill a pocket 2 mm deep and fill that with the resin. If you put the mating part on top and align it, you can even avoid scraping.

Don't use Moglice or Turcite etc. as they are too slippery. Not a good idea on a tailstock.


Nick

[Mcgyver]

Don't use Moglice or Turcite etc. as they are too slippery. Not a good idea on a tailstock.

that's a good point, hadn't thought of that.....I have been learning about the turcite process regarding the rebuilding of an old lathe, a Monarch 10ee, so its on the brain...but of course all those surfaces are primarily sliding vs. a tailstock which is locked in place taking a big load

I does though highlight a problem; after scraping, ending up with the barrel lower than the spindle. Connolly's solution is to scrape the headsctock down to match. Everyone groans at that as being a huge inbalance in work vs gain but I can see how its the 'job done right' solution. Shimming is a way to get things to height, but its sort of saying i'll live with an inferior build to avoid a bunch of work...maybe thats a bit too judgemental sounding, but its what it is - there may be lots of times when it is a compromise that makes sense.

Its a compromise imo because the tailstock to its base is a bearing surface that moves. It doesn't move often, but it does move....and I see having thin shim stock between to heavy bearing surfaces that move as being less than ideal.

Is there a way in between lowering the headstock and shimstock? What about milling some off the top of the base and then attaching with counter sunk screws a piece of 1/4" thick cast iron, that had been scraped flat of course. The loads is almost all compression and solid cast iron to cast iron is maintained for the bearing surface.

Does the condition of the tailstock barrel alter the approach? In Steve's case he's happy with the barrel fit so that becomes the reference point. I have a tailstock i'm not happy with....I'd toyed with the idea of line boring and then lapping the barrel after scraping the tailstock to the bed. Easy to say, not so sure its as easy to do...for one thing the line boring set up will have a very long bar hence have a lot of flex.

If the barrel also requires restoration, would you bore/lap it first (by whatever means) then align things as already desicribed? Or would you do the barrel last using the lathe bore it somehow. The later sure eliminates a lot of scraping challenges!

[MuellerNick]

Shimming the tailstock:
If you insert thin sheet metal, do it where there is the least movement. That would be between top and base.

Here's my voting how to fix TS height:
* scrape spindle stock down
* make TS higher with Multimetall.
* insert thick CI "shim" (I'd glue it with Locktite)
* classical shimming.

Fixing the TS's quill:
I helped a friend to fix his factory-worn-out quill. He made a mandrel a tad thicker than the original quill. Then we bored the TS 3 mm bigger on my mill. He then clamped the mandrel in the spindle head, slipped the TS over and cast the too big bore with Moglice. He didn't have to make geometric corrections. But it was more luck than knowledge (IMHO).
The best procedure I think is:
Crome the quill up on the outside by 0.2 mm or what is needed. Will cost you some bugs, but worth it. Then grind/lap it down to a constant diameter (it won't come out cylindrical after chroming). Now lap the TS bore to fit the quill. You'll get the best fit ever, better than factory made. But you'll have to accept that you will have to correct TS geometry. I wouldn't even try, because I think it will fail anyhow if you do it in the lathe. It will come out too low and not pointing in the right direction. The TS has to be a tad higher.

Albeit, you might temporarily shim up your spindle head while you do that. Then correct the TS by scraping. Might be worth a try.


HTH,
Nick