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View Full Version : Mini-Lathe Improvements, A WIP Thread



epicfail48
12-20-2017, 08:48 PM
Been saying id do it for a while, and here i am! Im the proud(ish) owner of a Grizzly g8688 lathe, and have always been of the opinion that while it works, it could work a lot better. I know the general opinion is that this class of machine is more a toy than tool and isnt appropriate for much of anything, let alone spending the time necessary to improve, but my opinion is the bones are there, and getting excellent performance (inside what can be expected for this class of machine) is just a matter of putting in some elbow grease.

First, lets meet the victim:
https://i.imgur.com/tS6k6Ijm.jpg

Pretty bog standard mini-lathe, almost no modifications. Now, it does work okay at the moment but ive had some issues with it. The first and most obvious is the plastic headstock gears, I broke the low-speed side a while back so that needs to be replaced. Still works in high gear though, barely. Sticking with the headstock, id also like to change out the stock radial bearings with a set of better quality tapered roller bearings. Ive had some serious issues with workpiece deflection, .005" of taper or more on ~1" parts, and im fairly certain half the problem there is just bearing runout/slop.

The next problem im looking to correct is the movement of the cross and compound slides. Both work, but not particularly well. Im forced to either keep the gibs so tight movement is next to impossible, or loosen the gibs for easy movement but plenty of slop. Compounding the issue is the fact that even when the gibs are locked, theres still an unpleasant lack of rigidity in the setup. Im pretty certain that this particular problem can be attributed to poor contact at the ways, and to correct that ill be trying my hand at scraping in the ways. Backlash on the 2 slides is also a problem. A minimal one to be sure, but one ill be attempting to correct by the addition of Delrin feed-screw nuts.

The rest of what ill be doing to this lathe is a touch more standard. A carriage lock, carriage stop, and cam-lock tailstock are also on the list, as is a fine powerfeed mechanism separate from the lathe drive train

epicfail48
12-20-2017, 08:55 PM
So, to recap what ill be doing to this lathe:

-Scraping in the ways of the compound- and cross-slide
-Delrin nuts for the cross- and compound-slide
-Replace the plastic headstock gear with a metal one
-Replace the stock bearings with a set of tapered roller bearings

That completes what ill be doing to try to address the mechanical accuracy. The separate list to improve usability is:

-Carriage lock and depth stop
-Tailstock camlock + improve tailstock alignment
-Fit fine powerfeed mechanism, separate from the main drivetrain

I may or may not add to either of these lists. The first thing ill be starting on is scraping in the ways on the slides, so i can get out the most difficult thing first.

danlb
12-20-2017, 09:48 PM
It sounds like a good endeavor. I use my 7x12 a lot, and found that adjusting ALL the gibs was important to allow easy, consistent and accurate use. By putting dial indicators on the bed, apron, cross-slide and compound I was able to find out exactly where the movement was.

May I suggest that before scraping the ways that you straighten and lap the gibs? Sometimes they pick up a banana shape that causes erratic contact.

I don't worry much about the backlash. The proper technique of infeed is needed whether you have .001 or .010 backlash.



I look forward to your thread.

epicfail48
12-21-2017, 02:33 AM
So, part 1, scraping in the slides! Ill be starting with the compound slide, just cause its the smallest and easiest to replace if i screw up. First things first, a disassembly and cleaning to see what im working with:
https://i.imgur.com/WJcifBYm.jpg

So im going to call the bit on the left the saddle and the bit on the right the base. So, to start with im going to scrape in the bottom of the saddle. Initial bluing:
https://i.imgur.com/xkiJXlXm.jpg

Yeah, not too great on the whole 'flatness' thing. In case you cant really see it, theres only blue on the very corners, and not much at that. Few rounds of scraping:
https://i.imgur.com/mAPYgZXm.jpg

Getting a little closer. Few more iterations:
https://i.imgur.com/V46exrX.jpg

Id say thats a pretty good bearing surface. Better than the start at any rate.

epicfail48
12-21-2017, 02:34 AM
Now, onto the base, but there we hit a problem:
https://i.imgur.com/cscxNb0.jpg

It shows just a bit in the photo, but the right side is nearly 5 thou lower than the left. Honestly, not sure at this point how im going to correct that, it seems like a little much to attempt to correct via scraping while keeping everything in plane. I might throw it on the mill with a dovetail cutter and just skim it. Of course, the other problem is my present scraper is too thick to scrape into the corners of the dovetails. Both problems for another day!

vpt
12-21-2017, 08:53 AM
Every time I see or hear of these small lathes I think of this video.

Clank clank, screech, thunk thunk thunk, "looks pretty good".


https://www.youtube.com/watch?v=IwJiyFiqxTE

danlb
12-21-2017, 12:43 PM
I watch that video and see that none of his gibs are properly adjusted. You can see the toolpost tilt to the left as the cross slide lifts on the right side. Later in the video it looks like the compound gibs are loose too, as it looks like the tool post is tipping forward under load too.

Of course, as soon as the tool breaks off a bit of aluminum it's no longer under load it springs back to normal and starts all over again. It's a perfect training film of what not to do.


Dan

Mcgyver
12-21-2017, 01:04 PM
rly 5 thou lower than the left. Honestly, not sure at this point how im going to correct that, it seems like a little much to attempt to correct via scraping while keeping everything in plane. I might throw it on the mill with a dovetail cutter and just skim it. Of course, the other problem is my present scraper is too thick to scrape into the corners of the dovetails. Both problems for another day!

The horizontal surfaces being at different heights doesn't much matter....the do have to be parallel though. You have to make small scrapers to fit in small dovetails and you will need to relieve those dovetails....can't scrape them properly otherwise. Relieve with a heavy old power hacksaw blade or in the mill. Something with a radius is nice, no stress riser (this cutter was originally used for fluting taps and Bertram (P&W)) but not critical, lots are done with straight cutters

And to put in oil passages and cups while its apart, every machine should have them and its surprising how many don't

https://i.imgur.com/EkngYbG.jpg

https://i.imgur.com/GVz2HNB.jpg

https://i.imgur.com/xJPEHm5.jpg

epicfail48
12-21-2017, 02:11 PM
The horizontal surfaces being at different heights doesn't much matter....the do have to be parallel though. You have to make small scrapers to fit in small dovetails and you will need to relieve those dovetails....can't scrape them properly otherwise. Relieve with a heavy old power hacksaw blade or in the mill. Something with a radius is nice, no stress riser (this cutter was originally used for fluting taps and Bertram (P&W)) but not critical, lots are done with straight cutters

And to put in oil passages and cups while its apart, every machine should have them and its surprising how many don't

https://i.imgur.com/EkngYbG.jpg

https://i.imgur.com/GVz2HNB.jpg

https://i.imgur.com/xJPEHm5.jpg

Oilcups, thank you! I knew I was forgetting something on that list. May not end up with them on the compound, but I'd definitely like to put them on the cross slide and carriage ways.

I'd like to have the surfaces at the same height to prevent an extreme amount of tilt from interfering with tool clearances. As it is now, if I were to flatten the 2 ways on the base, I'd imagine I'd end up with 3-4 degrees of tilt left-to-right. May not actually affect anything in real life, but still something I'd like to address.

As for the relief groove, I knew I needed to put one in but I'm still trying to make up a way how. A mill with a slitting saw would be my first choice, but thatd require a non-insane setup and a slitting saw, neither of which I have. Given the low criticality, I was honestly thinking of going in there with a cutting disk on a pencil grinder

For the scraper I was considering just making a carbon steel one. I know the edge wouldn't last very long, but the dovetails are small, I've got a lot of carbon steel hanging around and I'm just not set up for grinding carbide

Mcgyver
12-21-2017, 02:37 PM
I'd like to have the surfaces at the same height to prevent an extreme amount of tilt from interfering with tool clearances. As it is now, if I were to flatten the 2 ways on the base, I'd imagine I'd end up with 3-4 degrees of tilt left-to-right. May not actually affect anything in real life, but still something I'd like to address.

I'm not sure I follow. The top of the stack where the tool post mates has to be parallel to the lathe bed horizontal way, but that doesn't mean the cross slide horizontals have the coplaner. Parallel yes, but not coplaner. You'd like that them to be coplaner and its convenient to have them so, but if you're concerned there is so much to scrape, you can (with zero detriment to objectives) scrape them parallel but not coplaner and get back to flat to the bed on the next surface

danlb
12-21-2017, 03:43 PM
Just to add a data point.

I just checked my 7x12 lathe. First, a metal straightedge was laid across the plinth and a nice new Mitutoyo caliper was use to check the distance to the tops of the both ways. They measured exactly the same over that 4 inch space. Conclusion; the plinth is parallel with the ways.

Second, I checked the thickness of the bottom part of the compound slide since it sits on the cross-slide. This was measured to the left and right of the male dovetail. The side with the the gib was .002 taller than the other side. Again, using a straightedge to magnify error. I measured 4 inches out from the end of the compound and found both matched the previous discrepancy. Conclusion; the surfaces are parallel but not on the same plane.

Conclusion; It appears to me that they did grind these two pieces as matched sets. Maybe they just assembled them and then ran them through a surface grinder so that the relevant surfaces were parallel and flat??

Suggestion; I would not try to make them coplanar since that would require grinding the top of the plinth to match.

Dan

epicfail48
12-21-2017, 06:21 PM
Just to add a data point.

I just checked my 7x12 lathe. First, a metal straightedge was laid across the plinth and a nice new Mitutoyo caliper was use to check the distance to the tops of the both ways. They measured exactly the same over that 4 inch space. Conclusion; the plinth is parallel with the ways.

Second, I checked the thickness of the bottom part of the compound slide since it sits on the cross-slide. This was measured to the left and right of the male dovetail. The side with the the gib was .002 taller than the other side. Again, using a straightedge to magnify error. I measured 4 inches out from the end of the compound and found both matched the previous discrepancy. Conclusion; the surfaces are parallel but not on the same plane.

Conclusion; It appears to me that they did grind these two pieces as matched sets. Maybe they just assembled them and then ran them through a surface grinder so that the relevant surfaces were parallel and flat??

Suggestion; I would not try to make them coplanar since that would require grinding the top of the plinth to match.

Dan

Works for me! Thanks for the data points mate, I might still go through and do the same measurements on mine just to be sure, but if the same story holds true for mine it'll be nice to avoid the extra work

danlb
12-22-2017, 10:28 PM
BTW,

If you want to check to see if your lathe is abnormal, I have access to 3 similar lathes, a 1990s HF 7x10, a 2004 SIEG 7x12 and a 1996ish HF 9x20 which can be used to see if a feature is deliberate VS a flaw.

Since they are from different eras and models there is a good chance that any feature/flaw that is in more than one will be there for a reason. It may be a bad reason, but that's harder to divine. :)

Dan

RB211
12-23-2017, 01:27 AM
This is a lot like taking a crap in a toilet, then adding gold leaf and paint to your crap in the toilet, to some how polish it up.
It's one thing to put work into a lathe that was properly built from the factory, and entirely another when nothing was machined correctly and made true. Typical Sieg quality. Go try to measure the tail stock, you'll probably take a sledgehammer to it afterwords in disgust.

3 Phase Lightbulb
12-23-2017, 01:45 AM
This is a lot like taking a crap in a toilet, then adding gold leaf and paint to your crap in the toilet, to some how polish it up.

Too many visuals.... Just say "polishing a turd" next time.. ;)

epicfail48
12-23-2017, 03:50 AM
This is a lot like taking a crap in a toilet, then adding gold leaf and paint to your crap in the toilet, to some how polish it up.
It's one thing to put work into a lathe that was properly built from the factory, and entirely another when nothing was machined correctly and made true. Typical Sieg quality. Go try to measure the tail stock, you'll probably take a sledgehammer to it afterwords in disgust.

Curious them, what would you suggest? Yeah, might be lipstick on a pig, butyou know what's worse than a crappy lathe with a lot of work in in?

No lathe at all

3 Phase Lightbulb
12-23-2017, 09:34 AM
Curious them, what would you suggest? Yeah, might be lipstick on a pig, butyou know what's worse than a crappy lathe with a lot of work in in?

No lathe at all

I think fixing or re-working equipment to perform better is a skill few people have and fewer are acquiring. I tend to rather spend money instead of fix/upgrade and I'll have nicer tools, but at the cost of being less of a machinist as I'm just exercising my wallet and not improving my machinist skills in the process. Time is probably the most scarce so that and interest level are usually the deciding factors for me.

RichR
12-23-2017, 11:06 AM
This is a lot like taking a crap in a toilet, then adding gold leaf and paint to your crap in the toilet, to some how polish it up.
It's one thing to put work into a lathe that was properly built from the factory, and entirely another when nothing was machined correctly and made true. Typical Sieg quality. Go try to measure the tail stock, you'll probably take a sledgehammer to it afterwords in disgust.

Curious them, what would you suggest? Yeah, might be lipstick on a pig, butyou know what's worse than a crappy lathe with a lot of work in in?

No lathe at all

Pay no attention to RB211, his self loathing sometimes makes him behave like an ass. He's just trying to make himself feel superior by putting
down your goals and abilities. By improving the fit and function you gain a skill set and wind up with a machine that operates more smoothly.
I personally feel your quest is worthwhile and will be following along. Most of the other replies seem to be guiding you towards success, focus
on them and ignore the noise.

J Tiers
12-23-2017, 11:53 AM
The nay sayer(s?) are not thinking.

How much worse were the castings for a Monarch 10EE when they came in from "seasoning"? Right.... they looked like funny shaped pig iron at first, but when finished and assembled, they were a fine machine.

You have a lathe kit, which was pre-machined for you. Start with that idea. "It's a "lathe shaped object" that needs tuned up to be a real lathe. You can do that, given a little work and basic equipment.

For dovetails, grind one edge on the scraper down at a slope until the business end is thin enough for the end to go into the space, so the remaining edge can scrape all the way into the clearance groove.

As for the video.... that was painful to watch. At least the guy could have bolted down his "lathe shaped object".... it jumped every time he took a cut.

RMinMN
12-23-2017, 01:53 PM
I'd like to applaud you people for even tolerating a discussion about a mini lathe. When I got mine and was starting to learn a little about using it and modifying it to do more of what I wanted, I bookmarked a number of machining sites and would visit them regularly. One of those I discarded when the owner blacklisted a bunch of contributors, most of which were answering questions accurately but the owner though were demeaning the novices. Some of you were in that list. The second site I discarded has a rule that small lathes and mills are never discussed because they aren't used by a practical machinist. I have used my mini lathe for a practical purpose more than once. Then as time went on I noticed that many of the answers given were either wrong or condescending to the person asking so I removed that bookmark too.

I've learned a ton since I bought my mini lathe and mini mill, thanks to people like you. I'm nowhere near competent but I enjoy learning and doing projects.

epicfail48
12-23-2017, 01:54 PM
Appreciate the encouragement guys! I'll have more work stories posted soon, I'm still trying to decide if I want to replace mill the Dovetails. I did do some checks, and the top of the saddle where the tool post sits was not ground to be parallel to the base, there's a pretty considerable slope to it. I'm probably going to blue up the ways a little more and see just how close everything is, then decide if I want to kill the ways or just bring the top parallel with the bottom

3 Phase Lightbulb
12-23-2017, 02:08 PM
How does the MicroLux 7x14" lathe compare to the others out there? I picked mine up at an auction not knowing much about the mini lathes.

http://www.bbssystem.com/pictures/mini5.jpg

http://www.bbssystem.com/pictures/mini1.jpg

tomato coupe
12-23-2017, 02:09 PM
... The second site I discarded has a rule that small lathes and mills are never discussed because they aren't used by a practical machinist. I have used my mini lathe for a practical purpose more than once ...

The site you're referring to does not allow discussion of said machines because they normally aren't used by professional machinists, which is its target demographic.

RB211
12-23-2017, 02:14 PM
I had a microsux mini lathe, sorry to say, that’s where my bad taste comes from. They are all made in the same factory by the same unskilled craftsman not doing proper checks.


Sent from my iPhone using Tapatalk Pro

3 Phase Lightbulb
12-23-2017, 02:21 PM
I had a microsux mini lathe, sorry to say, that’s where my bad taste comes from. They are all made in the same factory by the same unskilled craftsman not doing proper checks.


Sent from my iPhone using Tapatalk Pro

What problems did you have with yours? I'm disappointed by the lack of power as it stalls it stalls very easily but when taking very lite cuts it seems to function really well for such a small lathe that you can basically carry away under one arm for a few seconds :)

danlb
12-23-2017, 02:24 PM
How does the MicroLux 7x14" lathe compare to the others out there? I picked mine up at an auction not knowing much about the mini lathes.




The Microlux brand is often considered to be top of the class. Rumor is that they commissioned their own beds, making them a bit stiffer than normal. They were one of the first of the asian machines to provide leadscrews based on imperial threads.

Having a second lathe is really handy. You can use it for second operations without disturbing the setup on the other lathe. You can also use it to make parts for your other lathe if something breaks. :)

The key to working with all of these lathes is to properly adjust the gibs and check that everything is lubed and aligned. Use sharpened tools that are properly aligned and they will work as well as any other lathe (within their work envelope).

Dan

01-7700
12-23-2017, 02:29 PM
Appreciate the encouragement guys! I'll have more work stories posted soon, I'm still trying to decide if I want to replace mill the Dovetails. I did do some checks, and the top of the saddle where the tool post sits was not ground to be parallel to the base, there's a pretty considerable slope to it. I'm probably going to blue up the ways a little more and see just how close everything is, then decide if I want to kill the ways or just bring the top parallel with the bottom

I have one of the Grizzly mini lathes, it was my first. It's not the most able piece of equipment but for making small parts it is adequate. I have made enough money with that toy lathe to pay for itself and buy a turn-of-the-century Southbend and a mill drill and then some 3 times over. I'm going to use the mini lathe to make bushings for the Southbend in a lathe rescue. So yeah, it has it's uses and limitations. Better to not be impaired by a lack of imagination that some here have expressed. More power to you if you have the money to buy the biggest and best lathe. It's not the quality of the metal tool that makes the machinist, it's the quality of the grey matter that matters most.

RB211
12-23-2017, 02:34 PM
Because I was asked, my own lathe is a Lathe Master 8x14 which is the same as the HF 8x12. It is not a Sieg product and it’s a FAR better lathe for a slightly larger foot print. I rate its capabilities to that of a South Bend 9” model C lathe, but without being clapped out.
Listen, I fully respect the skills needed to bring this mini-lathe back into square, my problem is the “WHY”. It has design flaws that cannot be corrected.


Sent from my iPhone using Tapatalk Pro

Mcgyver
12-23-2017, 02:37 PM
Learning scraping to get things mating and aligned properly is a fantastic skill. If you think about it, a failure of the manufacturer to create the proper fit and alignment just about is what puts a machine into the poor quality catagory. Epic, I would encourage you to approach the lathe as a reconditioning situation which means everything gets fixed, you have to plan and think through a sequence. You'll learn a ton and quite possibly end up with a great little lathe.

I've also encouraged people before to pick a machine that is worthy of the full monty, as its a heck of lot work....makes more sense to do so on a Porsche than a Chevette. While I think that is still good advice, you go with what you've got. Its a small lathe so won't take the time a bigger one would. You can for sure improve it and what you will learn about accuracy, fit and alignment will serve you well with any project....so have at it and ask away if you have questions.

danlb
12-23-2017, 02:59 PM
Now that you have scraped in the bottom of the compound, has it changed the original issue? If I recall, it was that you could not adjust the gibs for easy movement without unwanted slop.


Dan

RMinMN
12-23-2017, 03:04 PM
Because I was asked, my own lathe is a Lathe Master 8x14 which is the same as the HF 8x12. It is not a Sieg product and it’s a FAR better lathe for a slightly larger foot print. I rate its capabilities to that of a South Bend 9” model C lathe, but without being clapped out.
Listen, I fully respect the skills needed to bring this mini-lathe back into square, my problem is the “WHY”. It has design flaws that cannot be corrected.


Sent from my iPhone using Tapatalk Pro

Your 8x12 weighs more than twice what my 7x14 does (which is good) and costs nearly double what my little one does. Part of why I got the smaller one is that I could wrestle it down the stairs to the basement and get it up onto a bench by myself. The other part is that I have a 10x24 lathe also, but it is in an unheated garage and since I live in northern Minnesota, it is unusable for several months of the year. I have to save the larger projects until warmer weather. I can learn a lot about the use of the lathe with the little one and with more safety as it isn't powerful enough to rip my arm off.

RB211
12-23-2017, 03:08 PM
Your 8x12 weighs more than twice what my 7x14 does (which is good) and costs nearly double what my little one does. Part of why I got the smaller one is that I could wrestle it down the stairs to the basement and get it up onto a bench by myself. The other part is that I have a 10x24 lathe also, but it is in an unheated garage and since I live in northern Minnesota, it is unusable for several months of the year. I have to save the larger projects until warmer weather. I can learn a lot about the use of the lathe with the little one and with more safety as it isn't powerful enough to rip my arm off.

There was a point in time you could buy them for 600$ from HF with coupons. If you take it apart, its much more manageable. If your working on small projects, I find the Taig mini lathe to be cheaper and much better as its ready to go and machined perfectly true, as long as its work envelope works for you.

epicfail48
12-23-2017, 07:05 PM
Now that you have scraped in the bottom of the compound, has it changed the original issue? If I recall, it was that you could not adjust the gibs for easy movement without unwanted slop.


Dan

You know, I haven't actually checked that yet, everything still disassembled. It's been a busy week for me, so I haven't got a whole lot of anything done. Certainly be interesting to test though, I get the feeling the movement will be a little smoother even with just that small amount of work done. Still have a load of work to do though, I'm not looking forward to checking the parallelism of the Dovetails...

epicfail48
12-23-2017, 07:09 PM
OH! I finally remembered what I forgot to add in my original to-do list:

New Gibs

Presently the Gibs are just the stock ones. I figure I can either go through the trouble of improving the stock mystery metal ones and hope they work okay, or I can take the extra 10 minutes to make some new cast iron ones. Given everything else, I'd rather take the time and do it properly

AD5MB
12-23-2017, 07:43 PM
going back to that piston video - from 0:53 50 1:08 - do those measurements sound like a rather robust cut to make a piston ring groove wider? if you have to cut an extra 41 100ths, just how wide is this ring?

danlb
12-23-2017, 08:08 PM
going back to that piston video - from 0:53 50 1:08 - do those measurements sound like a rather robust cut to make a piston ring groove wider? if you have to cut an extra 41 100ths, just how wide is this ring?

I'd say that video is basically off topic since it is a demonstration of doing everything wrong and yet still able to get a usable result. After all, he could not even explain a measurement without getting it wrong.

Obviously a mistake. 41/1000 is more likely. Almost 1/2 inch for a ring is really out of bounds.

Dan

CCWKen
12-23-2017, 09:45 PM
Every time I see or hear of these small lathes I think of this video.

Clank clank, screech, thunk thunk thunk, "looks pretty good".


https://www.youtube.com/watch?v=IwJiyFiqxTE
That poor guy didn't know what a lathe was but had to justify the $500 to the wife (taking the video). Man, that thing was jumping all over the place. I was waiting for the cutoff tool to snap and hear him blame the piston. :cool:

vpt
12-23-2017, 10:07 PM
It is quite comical!

I am sure Epicfail will true up his lathe and it will perform very well within its limits. Even my Atlas does alright within its limits, just can't hog off material.

01-7700
12-24-2017, 07:51 AM
That poor guy didn't know what a lathe was but had to justify the $500 to the wife (taking the video). Man, that thing was jumping all over the place. I was waiting for the cutoff tool to snap and hear him blame the piston. :cool:

He has come a long way since that video - and spent a ton of money on that hole in the water.

CCWKen
12-24-2017, 08:32 AM
I watched some of his other videos. If he built the submarines the same way he rebuilt that engine, it's no wonder they went up for sale. It gives credence to the law of not buying a submarine built in Oklahoma. I was laughing so hard at that wooden one with the "wheels" on the bottom with a hand crank, I almost hurt myself.

01-7700
12-24-2017, 10:14 AM
Agreed. Anyone who wants to sign on for duty aboard his research vessel should be encouraged to first watch his early videos. LOL

garyhlucas
12-24-2017, 12:28 PM
If I was in the market for a Mini-Lathe I would happily pay MORE than retail to get this one when he gets it done!

Toolguy
12-24-2017, 01:00 PM
The spindle and ways are the heart of any machine tool. Get that right and you've got a usable machine. I had a 12 x 40 lathe bought new in 1995. The intention was to use it for a year or 2 until I could upgrade to something better. I spent the first 2 weeks reworking it, many of the same problems on all the Chinese imports. Ended up using it to earn a living on for 18 years. At the end of that time I sold it for more than I paid and it was still in better shape than when I got it new.

All this is to say that I think the rework in this thread will be entirely worthwhile and satisfactory at the end. There is also a certain pride of ownership in a machine that one has brought up to snuff, and much enjoyment to be had in using said machine. Soldier on, EF!

RB211
12-24-2017, 08:36 PM
The bed ways are narrow, the cross slide ways are narrow, the tail stock will need to be rebored so it’s actually true. He can make everything perfect, and I applaud, and admire the skill required, but you aren’t going to fix the design problems.

danlb
12-24-2017, 09:33 PM
The bed ways are narrow, the cross slide ways are narrow, the tail stock will need to be rebored so it’s actually true. He can make everything perfect, and I applaud, and admire the skill required, but you aren’t going to fix the design problems.

RB, you are polluting the thread with assertions that only apply to the one machine that you had. That's a disservice to people trying to learn from epicfail's work. My 3 HF lathes did not need work other than adjustments. That means that some of them work well without modifications. In my experience, if you can't do decent work with a 7x10, chances are you were still learning and did not adjust it or use it correctly.

Dan

adatesman
12-24-2017, 11:04 PM
Yet a 5 thou dip towards the chuck on an old American Lathe is acceptable.

Both are Lathe Shaped Objects, capable of holding tolerances based on the end user. Some can compensate and put out good work, and others can't.

It's a poor man who blames the tool.

J Tiers
12-25-2017, 12:13 AM
Yet a 5 thou dip towards the chuck on an old American Lathe is acceptable.

...

The actual difference in turned size for normal size workpieces is TINY with that change in height. Calculate it sometime for a workpiece of 1" or 0.5", you may be shocked by the tiny change.

Now. if the wear is all on the front way, so it TILTS the carriage, you can get some interesting results, depending on the width of the ways vs the height of the cutter.

Or if you are working with 0.090 diameter parts, that can have a larger effect also.

3 Phase Lightbulb
12-25-2017, 12:19 AM
Yet a 5 thou dip towards the chuck on an old American Lathe is acceptable.



Probably creates a perfect taper at the end of shafts for press-fitting bearings or hubs or whatever you want to press fit on the end :)

RB211
12-25-2017, 02:41 PM
Yet a 5 thou dip towards the chuck on an old American Lathe is acceptable.

Both are Lathe Shaped Objects, capable of holding tolerances based on the end user. Some can compensate and put out good work, and others can't.

It's a poor man who blames the tool.
Says the person that probably has a really nice lathe...

adatesman
12-25-2017, 02:54 PM
Says the person that probably has a really nice lathe...

I have a tiny Sherline and a rather worn Clausing 5900. Neither fall into the "really nice" category, but both can put out good parts provided I do my part.

RB211
12-25-2017, 03:06 PM
I have a tiny Sherline and a rather worn Clausing 5900. Neither fall into the "really nice" category, but both can put out good parts provided I do my part.

The Sherline from the factory is true, everything machined and fitted perfectly, as was the Clausing when new, and the Clausing has nice wide ways, a well balanced machine. You can easily adjust for wear and tear on those machines. You aren't fighting design flaws.

adatesman
12-25-2017, 04:14 PM
The Sherline from the factory is true, everything machined and fitted perfectly, as was the Clausing when new, and the Clausing has nice wide ways, a well balanced machine. You can easily adjust for wear and tear on those machines. You aren't fighting design flaws.

I'm guessing you've never actually used a Sherline? They're quite limber and the combination of plastic gibs and aluminum-on-steel sliding surfaces aren't exactly well fitted or well designed.

As for the Clausing, yes it was a fairly nice lathe when new. Mine is far from that condition.

RB211
12-25-2017, 06:20 PM
I'm guessing you've never actually used a Sherline? They're quite limber and the combination of plastic gibs and aluminum-on-steel sliding surfaces aren't exactly well fitted or well designed.

As for the Clausing, yes it was a fairly nice lathe when new. Mine is far from that condition.

I’ve had Taigs, thought they were great. Surprised to hear that Sherline isn’t as good

The Artful Bodger
12-25-2017, 06:31 PM
I have two of the original brass bed Sherlines but one is missing the headstock. Neither is at all worn.

epicfail48
12-25-2017, 07:31 PM
Says the person that probably has a really nice lathe...

I can second the original statement. I can hold tolerances of a few thousand on this lathe as-is, it's just a pain in the bloody rear and usually takes a little hand work

tomato coupe
12-25-2017, 11:00 PM
I can hold tolerances of a few thousand on this lathe as-is, it's just a pain in the bloody rear and usually takes a little hand work.

What does "a little hand work" entail?

epicfail48
12-26-2017, 05:42 AM
What does "a little hand work" entail?

The occasional bit of file work or polishing. Nothing major of course, and only on critical bits

mygrizzly1022
12-26-2017, 11:35 AM
epicfail48
Do not be discouraged by the negativity of some of the comments. To quote my Father ”It is p-ss poor tradesman that blames his tools” . The internet is awash with fine examples of the work that in skilled hands they can produce. So, to say they are crap is “FALSE NEWS” .Those lathes are a big bang for the buck and any improvements you make only make the bang bigger. I started with one and moved on when I thought I had outgrown it. I sold it and have kicked my but ever since, because having it around for the jobs it is very good at is worth more than what I got when I sold it. I got what I paid for it, but gave the tooling away. Big dumb!!

Bert

tomato coupe
12-26-2017, 11:35 AM
I can hold tolerances of a few thousand on this lathe as-is, it's just a pain in the bloody rear and usually takes a little hand work.

"What does "a little hand work" entail?"


The occasional bit of file work or polishing. Nothing major of course, and only on critical bits

What tolerance can you hold on this lathe without the followup hand work?

The Artful Bodger
12-26-2017, 01:51 PM
Shoe box lathe...

http://farm6.static.flickr.com/5176/5511632818_2a20e1e634.jpg

...quite handy for truing up the wheels I make for Lego trains.

3 Phase Lightbulb
12-26-2017, 02:00 PM
Shoe box lathe...

http://farm6.static.flickr.com/5176/5511632818_2a20e1e634.jpg

...quite handy for truing up the wheels I make for Lego trains.

You going to put a DRO on that bad boy? :)

The Artful Bodger
12-26-2017, 02:15 PM
You going to put a DRO on that bad boy? :)

Oh yes, but first it will be getting a QCTP, a taper attachment, 3 phase and VFD but none of that will happen until I get a precision level and get it set up properly.

Doc Nickel
12-26-2017, 02:18 PM
It always amuses me when somebody will denigrate a new import lathe, exclaiming that one has to do so much work to them to make them decent- had fit parts, deburr, readjust gibs, do minor repairs on things one should not have to repair, etc.

And then turn right around and recommend that you instead buy a used American machine, which, they say, are available in abundance, and "usually just need some work to repair and clean up". :D

By all means, do carry on. :)

Doc.

The Artful Bodger
12-26-2017, 02:37 PM
Dont forget all the free sand that you get with an import machine.

J Tiers
12-26-2017, 03:22 PM
It always amuses me when somebody will denigrate a new import lathe, exclaiming that one has to do so much work to them to make them decent- had fit parts, deburr, readjust gibs, do minor repairs on things one should not have to repair, etc.

And then turn right around and recommend that you instead buy a used American machine, which, they say, are available in abundance, and "usually just need some work to repair and clean up". :D

By all means, do carry on. :)

Doc.

They are usable. Usually.

If you buy a used but decent condition US, UK, German, East European, or better brand asian machine, you will get the features of a "real" lathe, back gear, a real QC box, wide range threading without changing gears, and a machine that was made to fine tolerances and made to work hard, and well.

If it has wear, and it will, you can evaluate that and see if it is too much for your use. Some wear may still be better than having no wear, but instead having lousy fit and finish.... like the low cost "master precision" level I bought, that turned out to only sit on 3 of its four corners.... your choice which three. Not so good if the crosslide is like that.

Any given machine may be better than that. Maybe a LOT better. And some sources are better than others. A lot of perfectly usable machines are imported from the cheap asian sources.

With the low cost, made-to-a-price asian machines, you may get a solid machine with lots of cast iron, but you may also get a lot of fluff features in an attempt to make up for a lack of basic fit and finish. Basically pinstripes, cupholders, and heated seats to make up for the lack of other more expensive features, or the lack of basic "fitting".

Maybe you are OK with that, and maybe you are not.

You CAN use either one. You CAN use a machine that is not perfect. Just depends on which way you want your "not perfect" to be.

epicfail48
12-26-2017, 05:44 PM
"What does "a little hand work" entail?"



What tolerance can you hold on this lathe without the followup hand work?

Depends on how careful I'm being and the shape of the part, as well as the material. Straight cylinder with no shoulders and somewhere I can use a shear cut bit with a slow feed, I can get ~+-.001. Other lower precision stuff I can usually get withing about +-.003 if I'm paying attention, though honestly the stuff I make either needs to be dead nuts or nobody cares in terms of accuracy, so I'm either shooting for an exact fit or "eh, close enough"

tomato coupe
12-26-2017, 06:35 PM
Depends on how careful I'm being and the shape of the part, as well as the material. Straight cylinder with no shoulders and somewhere I can use a shear cut bit with a slow feed, I can get ~+-.001. Other lower precision stuff I can usually get withing about +-.003 if I'm paying attention, though honestly the stuff I make either needs to be dead nuts or nobody cares in terms of accuracy, so I'm either shooting for an exact fit or "eh, close enough"


I can second the original statement. I can hold tolerances of a few thousand on this lathe as-is, it's just a pain in the bloody rear and usually takes a little hand work

I've never seen one of these lathes, much less used one. I'm trying to get a feel for what they can do, but I guess I'm a little too dense to understand what you're saying. Your first statement implies you can hit .001 without any "hand work" whereas your second statement implies you have to do some hand work most of the time in order to hold a few thousandths.

How about a different question: If you machine a part at some diameter, how closely will subsequent parts match it if you use only the hand wheels (or DRO?) for guidance, i.e. you don't make measurements and "sneak up" on the final dimension for each part? In other words, how repeatable is the lathe?

J Tiers
12-26-2017, 07:05 PM
Most of them are "1 thou" machines at best, at least the lathes, meaning you can, with care, probably hold 1 thou or so.

Hand work presumably means lapping, etc to get to a tighter tolerance, meaning that no, the machine itself is not really intended to hold anything better than 1 thou, and you will need to be fussy to get that.

Lots of machines in that category. Not just "asian" machines.

They probably differ most in how much hassle it is to get to the 1 thou. Some make it fairly easy, some need a lot of fussing. Some, of the same brand and model, may just not be well enough made to do it.

mattthemuppet
12-26-2017, 07:40 PM
You going to put a DRO on that bad boy? :)

I started out on something similar and it was better than no lathe, taught me a lot too. I did actually add some digital calipers as dros as it did have any dials on it

epicfail48
12-27-2017, 05:31 AM
I've never seen one of these lathes, much less used one. I'm trying to get a feel for what they can do, but I guess I'm a little too dense to understand what you're saying. Your first statement implies you can hit .001 without any "hand work" whereas your second statement implies you have to do some hand work most of the time in order to hold a few thousandths.

How about a different question: If you machine a part at some diameter, how closely will subsequent parts match it if you use only the hand wheels (or DRO?) for guidance, i.e. you don't make measurements and "sneak up" on the final dimension for each part? In other words, how repeatable is the lathe?


Most of them are "1 thou" machines at best, at least the lathes, meaning you can, with care, probably hold 1 thou or so.

Hand work presumably means lapping, etc to get to a tighter tolerance, meaning that no, the machine itself is not really intended to hold anything better than 1 thou, and you will need to be fussy to get that.

Lots of machines in that category. Not just "asian" machines.

They probably differ most in how much hassle it is to get to the 1 thou. Some make it fairly easy, some need a lot of fussing. Some, of the same brand and model, may just not be well enough made to do it.

Jtiers said it pretty well for me. The hand work only really comes into play when I need to hold a very tight tolerance, so yeah, lapping and the like. General use, the machine can be coaxed to hold tolerances of about .001" with care, but if I'm rushing it obviously gets a little higher.

Honestly, as far as what these machines can do, they can do whatever fits in their work envelope, just depends on how good the operator is. There are limitations you need to work inside of course, you won't be taking 1/4" cuts, need to take a spring pass, etc, but you can do good work.

Oh, and I've got no idea on repeated parts. Oddly enough I've never done more than 1 part per sitting...

JCHannum
12-27-2017, 09:57 AM
The fact of the matter is that holding 0.001" (and 0.005" much more realistically) is more than adequate for probably more than 95% of HSM work. I do not mean "Good enough for the girls I go with" work, but work that is functional and acceptable by any normal standard. The fit and finish of most HSM work is one off in nature and as long as part A fits and functions in concert with part B, mission accomplished.

RB211
12-27-2017, 11:19 AM
The fact of the matter is that holding 0.001" (and 0.005" much more realistically) is more than adequate for probably more than 95% of HSM work. I do not mean "Good enough for the girls I go with" work, but work that is functional and acceptable by any normal standard. The fit and finish of most HSM work is one off in nature and as long as part A fits and functions in concert with part B, mission accomplished.
It you’re building engines, even steam locomotives, there’s a ton of parts that require accurate lathe turning for fits, which means being able to turn to .001 on a regular basis a must for the times you need to be extra diligent to get that .0005. If you’re just turning things to have a profile for looks, sure .005 to .010 is fine, who cares.

JCHannum
12-27-2017, 11:53 AM
I didn't say that there are not instances where 0.001" accuracy is required. However, most parts are specified with +&- tolerances, and as long as the part falls within that tolerance range, it is acceptable. I suspect very few steam engine parts were specced with tolerances and fits within 0.001" TIR, and most HSM projects are outside of that range.

Machinery's Handbook and other sources define the tolerances required for diameters and fits.

vpt
12-27-2017, 05:29 PM
https://appleton.craigslist.org/tls/d/sherline-4000-metal-wood-lathe/6436771399.html


And


https://appleton.craigslist.org/tls/d/sherline-5400-vertical-mill/6436992484.html

RB211
12-27-2017, 07:42 PM
I didn't say that there are not instances where 0.001" accuracy is required. However, most parts are specified with +&- tolerances, and as long as the part falls within that tolerance range, it is acceptable. I suspect very few steam engine parts were specced with tolerances and fits within 0.001" TIR, and most HSM projects are outside of that range.

Machinery's Handbook and other sources define the tolerances required for diameters and fits.

Most people here prefer the smaller scales. You are well aware that smaller “stuff” requires higher precision. My apologies to anyone on this forum building a 1:1 scale steam locomotive. :)

JCHannum
12-27-2017, 08:15 PM
I am addressing the HSM which does encompass model steam engines. The same rules of fits apply there as well. Having built several model steam and IC engines, I have yet to see a print that specs to +- 0.001". Most express dimensions in fractional inches, which usually implies +-1/64". If building a working engine, such as a model airplane engine, the necessarily closer fits are usually achieved by secondary operations such as reaming and lapping.

RMinMN
12-28-2017, 07:14 AM
It you’re building engines, even steam locomotives, there’s a ton of parts that require accurate lathe turning for fits, which means being able to turn to .001 on a regular basis a must for the times you need to be extra diligent to get that .0005. If you’re just turning things to have a profile for looks, sure .005 to .010 is fine, who cares.

From reading your posts on this thread I find that you are either an elitist, have never run a 7X lathe, or have not adjusted and sharpened your tooling properly. My little lathe is not a big, high mass lathe. I work within its limitations but cutting within .001 isn't hard to do with a bit of care. I don't try to take a big bite. Little lathes just aren't built for that but they can do just fine with a bite commensurate with their size and reduced rigidity.

RichR
12-28-2017, 11:18 AM
@epicfail48: Sorry if this pulls your thread back on topic, but one improvement I made to my lathe was adding 2 more gib screws
to the compound. While I feel this improved the action and stability of the compound over it's full range of travel, here is the
initial reason I added them:
http://i62.tinypic.com/feknzc.jpg
As you can see, with the compound centered, there were a range of positions where only the center gib screw provided any
support.

This is the after picture:
http://i60.tinypic.com/1rq35c.jpg

If you are interested, additional details and more pictures can be found here:
http://bbs.homeshopmachinist.net/threads/64675-Added-some-gib-screws-to-my-Atlas-10-topslide

Looking forward to seeing the outcome of your efforts.

RB211
12-28-2017, 11:31 AM
From reading your posts on this thread I find that you are either an elitist, have never run a 7X lathe, or have not adjusted and sharpened your tooling properly. My little lathe is not a big, high mass lathe. I work within its limitations but cutting within .001 isn't hard to do with a bit of care. I don't try to take a big bite. Little lathes just aren't built for that but they can do just fine with a bite commensurate with their size and reduced rigidity.
Perhaps I am a flaming elitist when it comes to tools, but my clapped out Bridgeport mill, and 8x14 small lathe are anything but elitist tools. I have owned a 7x14 Micromark branded Sieg lathe, and have also owned a Sieg X3 milling machine. A new Sieg X3 milling machine can't even touch a 60 year old clapped out Bridgeport mill. If you really read my posts and listened to my words, you would realize that I am not really bashing the mini-lathe on its size. Yes, I think money is far better spent on the 8xXX lathes for the increased mass but is within the "ball park" in pricing. How many times have I said good things about the Taig micro lathe? A good lathe is a good lathe. The Mini-lathe is not a good lathe, sorry.

Mcgyver
12-28-2017, 11:38 AM
This gets thrown around now and again, what exactly is an elitist? I'd think of it perhaps as someone who looks down on others. I really like using nice tools and have worked hard to collect, recondition and acquire them over the decades. That list includes many of the best names there are machines. Its a choice made because I like the machines and tools and it has a big impact on the enjoyment level, for me anyway. Does that make me an elitist? I might not think much of a particular machine, but that hardly translates into a view on the quality and character of the person owning/using it. None of this stuff should be taken personally, they're just machines.

J Tiers
12-28-2017, 12:07 PM
An elitist in our terms (the actual definition is a bit different) is presumably someone who separates shops into the "worthy" and "unworthy" based on the machinery in them, and never misses an opportunity to remind others that he and his shop are "worthy" because he has the best stuff.

One who will argue the merits of machines, looking down on and "dissing" ones that are "not worthy", claiming that no decent work can be done unless it is done on the best machines, like his.

Often those folks actually DO very little, they just talk about it.

There are levels of this, of course.

We don't have too many "elitists" here.

Mcgyver
12-28-2017, 12:24 PM
The question was a bit rhetorical, intended to point out its just stuff we're talking about so who cares....it shouldn't be taken too personally or seriously.

What you've described seems like the type who think they can build themselves up by tearing others down which is never welcome. I really like my shop and collection, the effort into it was made because its important to me to use quality stuff but it doesn't affect me one way or the other if someone else takes a different approach. Heck I started with a unimat when I was 11 or 12....its journey and we're all at different places on different paths.

RB211
12-28-2017, 12:35 PM
I am on a mission to save people from buying a poor lathe, and I get that feelings get hurt by those who already own the mini lathe, but what I am suggesting in place of the mini-lathe is nothing spectacular. Here is the lathe I have but in red paint.
https://www.harborfreight.com/8-inch-x-12-inch-precision-benchtop-lathe-44859.html
With the every day 20% coupon, it is 799$ Even better if you find a 25% coupon. People in the past were able to buy these things for 600$

It's 3 times the lathe at least to this one...
https://www.harborfreight.com/7-inch-x-12-inch-precision-mini-lathe-93799.html
People complain that the 8x lathe has fewer features... Listen, if your willing to do what the OP is doing for his 7x, you could really take that time and make the 8x a much better piece of machinery, or JUST USE IT AS IS.
I will say this, and I speak from experience from using South Bend 9" lathes. If I got tired of looking for a used South Bend, or could only find a C model, I would go buy the 8x instead for a new lathe with induction hardened bed ways that isn't clapped out for the same price or less than a used South Bend C(depending where you live) without feeling any remorse.
With that said, I suspect all Chinese lathes, and certainly used American tools will show similar results to the one in this video. You can become mentally ill in this hobby if you go down this rabbit hole!

https://www.youtube.com/watch?v=D1eOQa1gYiU

RMinMN
12-28-2017, 12:45 PM
Perhaps I am a flaming elitist when it comes to tools, but my clapped out Bridgeport mill, and 8x14 small lathe are anything but elitist tools. I have owned a 7x14 Micromark branded Sieg lathe, and have also owned a Sieg X3 milling machine. A new Sieg X3 milling machine can't even touch a 60 year old clapped out Bridgeport mill. If you really read my posts and listened to my words, you would realize that I am not really bashing the mini-lathe on its size. Yes, I think money is far better spent on the 8xXX lathes for the increased mass but is within the "ball park" in pricing. How many times have I said good things about the Taig micro lathe? A good lathe is a good lathe. The Mini-lathe is not a good lathe, sorry.

If you will go back an reread the title of this thread and make suggestions following what the thread is about I will quit calling you elitist. Had the thread been about what Harbor Freight lathe to buy, why yes, the 8x14 is loads better than a 7x14. Your ballpark must be a little bigger than mine for the pricing to be in the ballpark with the 7x14 at $569 and the 8X14 at $999. I made my choice of the 7X14 based partly on the price, partly on the weight, and partly because its size fit what I wanted to do with it and I've learned quickly what needs to be done to make it work.

epicfail48
12-28-2017, 02:21 PM
I am on a mission to save people from buying a poor lathe, and I get that feelings get hurt by those who already own the mini lathe, but what I am suggesting in place of the mini-lathe is nothing spectacular. Here is the lathe I have but in red paint.
https://www.harborfreight.com/8-inch-x-12-inch-precision-benchtop-lathe-44859.html
With the every day 20% coupon, it is 799$ Even better if you find a 25% coupon. People in the past were able to buy these things for 600$

It's 3 times the lathe at least to this one...
https://www.harborfreight.com/7-inch-x-12-inch-precision-mini-lathe-93799.html
People complain that the 8x lathe has fewer features... Listen, if your willing to do what the OP is doing for his 7x, you could really take that time and make the 8x a much better piece of machinery, or JUST USE IT AS IS.
I will say this, and I speak from experience from using South Bend 9" lathes. If I got tired of looking for a used South Bend, or could only find a C model, I would go buy the 8x instead for a new lathe with induction hardened bed ways that isn't clapped out for the same price or less than a used South Bend C(depending where you live) without feeling any remorse.
With that said, I suspect all Chinese lathes, and certainly used American tools will show similar results to the one in this video. You can become mentally ill in this hobby if you go down this rabbit hole!

https://www.youtube.com/watch?v=D1eOQa1gYiU

Mate, unless that mission involves cash donations it ain't going to help much. $800 is $250 more expensive than the 7x12 goes for. You can rail on all you want about it being the better tool, but $250 is $250, and all the insulting comments you've made about people using the 7x12 and why they should just put in the effort to get the bigger machine completely ignore the fact that some of us don't have that money.

Elitism is looking at a problem and wondering why everybody else doesn't just throw money at it. After all, you did it, so why can't the rest of us, right? I bought this lathe for $100. If I hadnt, I wouldn't own a lathe. There was no other option, I had to, HAD TO work on a shoestring budget

J Tiers
12-28-2017, 03:03 PM
...
What you've described seems like the type who think they can build themselves up by tearing others down which is never welcome. I really like my shop and collection, the effort into it was made because its important to me to use quality stuff but it doesn't affect me one way or the other if someone else takes a different approach. Heck I started with a unimat when I was 11 or 12....its journey and we're all at different places on different paths.

I guess it could be called "excessive pride in ownership", the attitude of "I'm better because I have better stuff".

That Umimat was better than the AA/109 I started out using, and I bought that when I was a grown man who might have had the sense to avoid it. But I am actually glad I had it and used it... Taught me a lot.

RB211
12-28-2017, 10:28 PM
Mate, unless that mission involves cash donations it ain't going to help much. $800 is $250 more expensive than the 7x12 goes for. You can rail on all you want about it being the better tool, but $250 is $250, and all the insulting comments you've made about people using the 7x12 and why they should just put in the effort to get the bigger machine completely ignore the fact that some of us don't have that money.

Elitism is looking at a problem and wondering why everybody else doesn't just throw money at it. After all, you did it, so why can't the rest of us, right? I bought this lathe for $100. If I hadnt, I wouldn't own a lathe. There was no other option, I had to, HAD TO work on a shoestring budget

I’d suggest you pick a more affordable hobby for yourself. There’s a reason I am not involved in the Live Steam hobby anymore.

J Tiers
12-28-2017, 11:12 PM
I’d suggest you pick a more affordable hobby for yourself. There’s a reason I am not involved in the Live Steam hobby anymore.

Regrettably, that is NOT exactly helping..... It sounds even MORE elitist than almost anything that went before..... VERY similar to the snooty audio equipment folks who tell the person that they "are just not the right customer for this quality of equipment"..... as they are looking down their nose at the target of the statement.

Has a very strong flavor of "you are just too poor for this".... which is BS.

I suppose that it might not be quite the right time to say it, but one can get a decent used machine, Atlas or Logan or Southbend, for an amount of money similar to what EF is suggesting the 7 x 12 costs, including chucks and so forth.

NO, they are not all clapped-out wrecks as is usually suggested by the usual list of doom and gloom merchants. You know that they at the very least, were well-fitted and aligned when built. And they DO have larger swing, more center-to-center distance, actual back gears, not to mention being heavier, likely more solid, and capable of handling more power.

RB211
12-28-2017, 11:42 PM
Regrettably, that is NOT exactly helping..... It sounds even MORE elitist than almost anything that went before..... VERY similar to the snooty audio equipment folks who tell the person that they "are just not the right customer for this quality of equipment"..... as they are looking down their nose at the target of the statement.

Has a very strong flavor of "you are just too poor for this".... which is BS.

I suppose that it might not be quite the right time to say it, but one can get a decent used machine, Atlas or Logan or Southbend, for an amount of money similar to what EF is suggesting the 7 x 12 costs, including chucks and so forth.

NO, they are not all clapped-out wrecks as is usually suggested by the usual list of doom and gloom merchants. You know that they at the very least, were well-fitted and aligned when built. And they DO have larger swing, more center-to-center distance, actual back gears, not to mention being heavier, likely more solid, and capable of handling more power.
You’re right Jtiers, reading what I wrote sounds horrible. Perhaps I say things without a filter because it’s exactly what others had told me, in person, to my face. When I was living in San Francisco, I had lost my main job, and was fighting for table scraps. I belonged to the Golden Gate Live Steamers, and the only way I could enjoy the hobby was by volunteering. I was surrounded by incredibly wealthy people, and one of them said to my face, “you should really pick a hobby you can afford”. I took it as good advice, and not as an insult. I suppose I don’t sugar coat things and say things how I see it. That’s how people treated me growing up, and I understand the beauty in it. I am blessed now to have a well paying job, but it’s aviation and there’s no long term security in that. It’s all crap luck and I can wind up dirt poor again, I get it.
I don’t understand how anyone can enjoy this hobby with a tight budget, when simply buying raw materials can cost a few hundred dollars, and the tooling more than the machine itself.
Hey, you know what? I feel bad derailing this thread, I am sorry for doing that Epicfail, and I do appreciate the work you’re showcasing which is more than I have done lately.

danlb
12-29-2017, 12:13 AM
Thanks for that post RB211. Puts things in perspective.

I'm quite interested in epicfails adventure. I might learn enough to know what needs fixing to make my lathes just a bit better. :)

Dan

J Tiers
12-29-2017, 12:39 AM
Let's drag this back on topic.....

Th original mentioned issue is the crosslide etc apparently having slop in some places and being tight in others. Typical of wear, but in this case, probably more due to the original grinding and fitting (if any).

So.....

Start with crosslide:

Requirements....

1) shall allow smooth movement full travel with a single setting of the gib

3) Travel along the crosslide ways shall be aligned such that a facing cut provides a surface on the turned part which is between perfectly flat, and concave by 0.0005" for the full travel of 1/2 the lathe swing.

What to do:

Assuming the bed ways and carriage bottom are NOT being scraped, scrape crosslide and crosslide ways to provide the travel and alignment.

A) scrape the crosslide horizontal way surfaces flat and aligned (not necessarily co-planar).
I would suggest scraping the slide itself flat and aligned first, and using it as a reference for the alignment of the flat ways of the crosslide. It is a LOT easier if they are co-planar, so if that is feasible, do that. If not, I am not sure what to do, probably use a precision shim for spacer (of the appropriate thickness) under the short side when scraping the slide to the reference flat. WAY nicer if they are coplanar.

B) That leaves the dovetails.

To make them parallel so the gib setting can be consistent, measure them using the most precise pieces of round material you can get. Ones the diameter that is just a little smaller than the height of the dovetail are best. Dowel pins will work, and are not expensive.
For the male dovetail, measure across the two pins at several places, ideally with a mic good to 0.0001", but a 0.001" mic can be used if you pay attention to half divisions. You are using it to compare, and not make a calibrated measurement. Put a pin under each side, and measure across "over" them.

I would do a measurement first, write it down for each position along the dovetail. That's a reference for initial condition.
Now scrape both to be a flat surface. You will need a straightedge that fits into the dovetail. That can be made from a piece of cast iron, if need be. Make the angle less than the dovetail and you only need to finish one side.

Start with the headstock side. First, make it flat. Then put on the slide (which you have already scraped the dovetail of to make it flat) and check the alignment (see below). First make the two dovetails (headstock side of slideway and of slide fit each other, then check alignment with headstock. When the alignment is done, then QUIT working on that side, and do everything else on the tailstock side.

if the headstock side needed a lot of scraping, then toss your first measurements across the pins, and redo them.

As you scrape the tailstock side dovetail, take a bit more off the dovetail where the measurements show it to be "fat". Take that off the TAILSTOCK side. Do not mess with headstock side.

When the crosslide dovetail measures good, you should be done with it. You still need to final check alignment and travel smoothness.

Gib can be ordinary CRS, so long as it is flat. Drill pockets for the gib screws if you make a new one. CI is only good for ones that adjust from the ends, which that lathe does not have (IIRC from photos) .

Assemble, using oil liberally, and adjust to move smoothly but with no shake.... it should be very nice and smooth. Set it up, and check for smooth movement, and redo the alignment test to confirm.

To check the alignment with headstock, chuck up a piece of bent bar or similar.... need not be perfect, etc. Put an indicator on the slide, and, with the chucked bar on side toward you and horizontal, move carriage to where you get an indication on the bar. Lock carriage and then note indication. Turn bar 180 with the spindle (do not loosen anything) and slide the slide over to read the same spot on the bar. Max difference in readings is 0.001 on the full diameter, in a direction to make it concave.

This is pretty independent of the compound, so long as you keep the mount surface for the compound parallel to the flat portion of the slide's "slideways".

RMinMN
12-29-2017, 07:27 AM
Regrettably, that is NOT exactly helping..... It sounds even MORE elitist than almost anything that went before..... VERY similar to the snooty audio equipment folks who tell the person that they "are just not the right customer for this quality of equipment"..... as they are looking down their nose at the target of the statement.

Has a very strong flavor of "you are just too poor for this".... which is BS.

I suppose that it might not be quite the right time to say it, but one can get a decent used machine, Atlas or Logan or Southbend, for an amount of money similar to what EF is suggesting the 7 x 12 costs, including chucks and so forth.

NO, they are not all clapped-out wrecks as is usually suggested by the usual list of doom and gloom merchants. You know that they at the very least, were well-fitted and aligned when built. And they DO have larger swing, more center-to-center distance, actual back gears, not to mention being heavier, likely more solid, and capable of handling more power.

This would be a better suggestion if I didn't live in a machine desert. It would cost nearly as much for shipping as one of those lathes would cost just to get it to my place. What is worse is that I have a bigger lathe that apparently made by Okuma under their Crowne brand for Harbor Freight and it has had minimal use so it isn't worn. The problem with it is that it sits in an unheated garage and at the temperature now, I'm not sure the motor would turn even with all belts off. However I do have a comfortable basement with a mini lathe and what I learn to do with it can easily be translated to a larger machine when the weather warms. Following this thread is all about learning how to make my mini lathe work better so I can make the bigger lathe more useful.

dalee100
12-29-2017, 09:18 AM
The problem with it is that it sits in an unheated garage and at the temperature now, I'm not sure the motor would turn even with all belts off. However I do have a comfortable basement with a mini lathe and what I learn to do with it can easily be translated to a larger machine when the weather warms. Following this thread is all about learning how to make my mini lathe work better so I can make the bigger lathe more useful.

Hi,

Awww suck it up! The motor will run.:p It's only -17F out right now and I'm 220 miles south of you at the moment. Be up that way this afternoon headed to Northome. I expect to see hot chips flying as I drive through.

Enjoy your 7x, it will teach you things as you get familiar with it. Tweak and tune to your hearts content.

J Tiers
12-29-2017, 09:55 AM
The comment was aimed more at the OP, who is a couple hours from me and so has access to the machinery around here, of which there is a fair bit.

Bemidji is fairly far from my old stomping grounds in the Twin Cities, so you are in a worse spot.

flylo
12-29-2017, 11:45 AM
I had a HF 9x20 I sold a friend that I think is a decent chinese lathe with forum support & I liked the one plastic gear & even came with a spare. I never used it but he likes it & those can be found in good used shape for about $300-$400. I keep a Unimat in the house & it's a fine machine & has the option of being a mill. Most any lathe you can buy & use is better than no lathe at all & I think unless you only make one size item you need more than 1 lathe.

LibbyHillBrewer
01-03-2018, 02:07 PM
So, to recap what ill be doing to this lathe:

-Scraping in the ways of the compound- and cross-slide
-Delrin nuts for the cross- and compound-slide
-Replace the plastic headstock gear with a metal one
-Replace the stock bearings with a set of tapered roller bearings

That completes what ill be doing to try to address the mechanical accuracy. The separate list to improve usability is:

-Carriage lock and depth stop
-Tailstock camlock + improve tailstock alignment
-Fit fine powerfeed mechanism, separate from the main drivetrain

I may or may not add to either of these lists. The first thing ill be starting on is scraping in the ways on the slides, so i can get out the most difficult thing first.epicfail48,

This thread has unfortunately gone WAY off topic. Nevertheless, I am interested in your project and am following this thread. Please, continue!

Sent from my SM-G950U using Tapatalk

epicfail48
01-03-2018, 07:30 PM
epicfail48,

This thread has unfortunately gone WAY off topic. Nevertheless, I am interested in your project and am following this thread. Please, continue!

Sent from my SM-G950U using Tapatalk

Yeah, it took a bit of a left turn, one im sure i contributed to. Rest assured though, i plan on continuing it, just have a lot of projects going on. Need to free up a second to go back to this one!

RMinMN
01-04-2018, 06:36 AM
I'm glad you started this thread as I'm working with a mini lathe and want to make some improvements on it. Your thread has spurred me to spend time checking and adjusting the gibs on the cross slide more and that helped eliminate the movement but I then got them too tight for easy adjustment so I tweaked the adjustment screws a bit and seem to have easy movement back without the slack I started with. Then I took the saddle off and found one of the screws for the gibs there laying in the chip pan. That might have been one of the problems too. Thank you for the prod to work toward improving my lathe even though I won't likely go nearly as far on that as you.

Honest Don
01-04-2018, 02:15 PM
made by Okuma under their Crowne brand for Harbor Freight



LOL! That’s no Okuma


On topic though, this made a world of difference on my 7x:

http://www.arceurotrade.co.uk/machineguides/Mini-Lathe-Angular-Contact-Bearing-Change-Guide.pdf

epicfail48
08-29-2018, 04:56 AM
Ever been working on a project and something comes up and the next thing you know nearly 8 months have gone by and youre left with a pile of parts you only barely know what to do with?

Yeah, its been a hell of a year. I had got to work on the lathe thinking i had a bit of downtime, then relationship troubles cropped up, got a new job, my belt grinder and heat treat kiln both crapped out and so on and so forth and this project kinda got kicked by the wayside, leaving my lathe in a disassembled pile. Recently though i had a commissioned job that needed a few turned parts, so back together the pile went, and of course nothing worked quite right because it was a pile of broken parts.

Have a few more turning projects to do in the next few weeks, so i figured id get some of the easier stuff knocked out. I still need to do the more labor-intensive stuff like finish scraping in the ways, upgrade the bearings, etc, but that comes later. For now i figured id take everything apart, scrub it down, deburr some corners i never did when i got the thing, and finally get around to replacing that hi-lo gear i grenaded god knows how long ago.

So, after a few hours of profuse swearing knocking the spindle out to replace said gear, which had really failed quite spectacularly, i got everything reassembled and got to aligning the headstock, cause who doesnt enjoy that. Piece of 1/2 drill rod, a collet and the Rollies Dads Method of alignment is my preferred thing, so i got all that thrown on the headstock, placed the headstock on the base and decided to take a measurement before the bolts went in, just for giggles. Turns out, bloody near perfect, think i measured a few thou off on the horizontal and vertical axis's over 8 inches. Figured id save myself some time, pop in some .001 shims in the right places before i bolted everything in just to get ahead of the curve. Bolts go in and boom, 14 thou off on the vertical axis. Headscratching ensued, followed by repositioning of the shims. Second test, 4 thou off. Okay, getting closer, right? Another adjustment, another measurement, back up to 12 thou off, and this is all in the same direction, i didnt overcorrect. Profanity and threats were ineffective in fixing this problem, so i did some inspecting and found this:
https://i.imgur.com/dQlNcz3.jpg

Its faint, but in the top left corner of the prisms relief groove you can see the problem. Crack in the casting, right at the bolt hole. Bolt gets tightened, crack widens, throws everything out of whack. More swearing, followed by checking the price for a new headstock casting, followed by me deciding f--- it, im just going to slap everything back together and just barely snug that bolt, see what happens.

So, where im at now is everything is assembled and technically usable, so good there. Headstock needs to be replaced though, so now my decision is either get a full stock headstock assembly and throw it on there, or just buy a casting and all the upgrade parts, metal gears, taper bearings, 4 inch spindle, etc. Once i get that taken care of ill get back to the rest of the guts. Itll all be waiting a few weeks at any rate, ive got a few other tool purchases im trying to make. Grizzly is having a tent sale and im hoping to score a surface grinder, then use that to grind in the ways instead of scraping them! More to come!

johansen
08-29-2018, 10:45 AM
get the alignment right with the headstock's own weight on the bed.

then epoxy it on, then tighten the bolts a little bit.

J Tiers
08-29-2018, 11:33 AM
You might want to find the end of that crack, and drill a hole through there, to stop it from progressing.

Another idea would be to instead, drill a cross-hole from the side, and put in a screw to hold the pieces together. That will probably stabilize it as well as prevent iit extending.

epicfail48
08-29-2018, 05:11 PM
get the alignment right with the headstock's own weight on the bed.

then epoxy it on, then tighten the bolts a little bit.

Think that'd just leave me where I am now, the epoxy wouldn't stop the crack from opening up when any force is applied, and I'm 90% certain that includes cutting forces. Explains my rigidity issues

You might want to find the end of that crack, and drill a hole through there, to stop it from progressing.

Another idea would be to instead, drill a cross-hole from the side, and put in a screw to hold the pieces together. That will probably stabilize it as well as prevent iit extending.

I actually considered this, problem is there's nowhere to put a screw. There's next to nothing in the casting in that area, with the exception of the bolt hole, and if I put a screw there I couldn't also bolt the headstock down. I considered brazing and welding, struck both those off as more likely to cause other problems. Just going to have to bite the bullet and replace it

Mcgyver
08-29-2018, 05:17 PM
Explains my rigidity issuesit

maybe, partially. A lathe should have all components of the pancake stack with adequate bearing over their surfaces. Low cost lathes don't usually have that unless you scrape them

You made a comment about getting a grinder....how big a grinder and how long is the lathe bed? The correct procedure even if you grind the bed is to scrape the headstock, carriage and tailstock into the bed so it both fits the new grind and for alignment.

The Artful Bodger
08-29-2018, 05:27 PM
The headstock appears possible to repair but may be impractical so you would have nothing to loose by trying a bit of a bodge.

First of all ensure that everything is perfectly clean where it meets the prism and determine where the pressure is that opens the crack then gently scrape or grind that area until the crack no longer opens under pressure. Apply epoxy and position the headstock as accurately as possible. Tighten the bolts when the epoxy is cured.

epicfail48
08-29-2018, 06:22 PM
maybe, partially. A lathe should have all components of the pancake stack with adequate bearing over their surfaces. Low cost lathes don't usually have that unless you scrape them

You made a comment about getting a grinder....how big a grinder and how long is the lathe bed? The correct procedure even if you grind the bed is to scrape the headstock, carriage and tailstock into the bed so it both fits the new grind and for alignment.

6x12 Grizzly, assuming i can find one. Nothing fancy, just something to learn on. Touching the bed itself was never part of the plan for this project, maybe scraping the headstock, tailstock and carriage to the bed but not the bed itself. Funnily enough thats the one movement axis i havent had trouble with, minus those blasted gibs. Tapered saddle gibs might make the project list...

My biggest concern for this project is the dovetail ways, its more self-training than it is making a perfect tool anyway. Least thats what im telling myself to justify cutting a few of the weirder corners.


The headstock appears possible to repair but may be impractical so you would have nothing to loose by trying a bit of a bodge.

First of all ensure that everything is perfectly clean where it meets the prism and determine where the pressure is that opens the crack then gently scrape or grind that area until the crack no longer opens under pressure. Apply epoxy and position the headstock as accurately as possible. Tighten the bolts when the epoxy is cured.

I might try that, but i have very low hopes for any repair actually working. Crack pretty deep already, maybe 3/16-1/4", right at the relieve groove corner, and it heads straight up the line of the bolt hole. Add that to the prisms shape naturally trying to wedge things apart and i dont imagine anything short of a weld would hold, and that sounds like more worth than the headstocks worth. Its working for now at least, so its low on the list of shop priorities.

Appreciate the advise everybody!

johansen
08-29-2018, 06:31 PM
Think that'd just leave me where I am now, the epoxy wouldn't stop the crack from opening up when any force is applied, and I'm 90% certain that includes cutting forces. Explains my rigidity issues

you don't just epoxy the sides of the V, you put enough in there to fill up the whole cavity.

1200rpm
08-29-2018, 06:34 PM
or you just spend the 20 bucks for a new casting...:)

J Tiers
08-29-2018, 07:22 PM
If you can get a new casting, go for it.

I was thinking that a screw in from the side would go into the thickness of material in the wall of the headstock that has the spindle bearing in it. If the hold down bolt interferes, well that could be a problem. And if you can get a new casting that is machined, maybe you can just transfer the stuff over to it. Or get another headstock complete. There must be folks parting these things.

epicfail48
08-30-2018, 02:59 AM
If you can get a new casting, go for it.

I was thinking that a screw in from the side would go into the thickness of material in the wall of the headstock that has the spindle bearing in it. If the hold down bolt interferes, well that could be a problem. And if you can get a new casting that is machined, maybe you can just transfer the stuff over to it. Or get another headstock complete. There must be folks parting these things.

Little Machine Shop actually sells both options for replacement. I can either get a bare casting for $50 and transfer all the old parts to the new casting, pay $150 for a complete headstock with all the bits n pieces pre-installed, or pay $50 for the casting, plus order the 'upgrade' parts, namely angular contact bearings, metal speed gears and a spindle with a 4 inch flange. Im leaning towards the last option, given its all stuff id wanted to do anyway. Make hay while the sun shines and all that

1200rpm
08-30-2018, 07:22 AM
Grizzly sells that bare casting for 20 bucks!

https://www.grizzly.com/parts/HEADSTOCK-CASTING/P8688013

J Tiers
08-30-2018, 08:04 AM
With all the options of replacement, there must be known and serious issues with that part....... Seems really unusual to be able to get spare parts that easily.

epicfail48
08-30-2018, 01:57 PM
...huh. Whoopsie, didn't even think of checking them. Thanks!

danlb
08-30-2018, 03:28 PM
With all the options of replacement, there must be known and serious issues with that part....... Seems really unusual to be able to get spare parts that easily.

What makes you say that? I can get spare parts for every part of my car despite it's outstanding reliability. When you have a casting that is common to all the machines of that design made for 30 years it's easy to stockpile a few of everything.... if you are big enough.

Dan

J Tiers
08-30-2018, 03:49 PM
What makes you say that? I can get spare parts for every part of my car despite it's outstanding reliability. When you have a casting that is common to all the machines of that design made for 30 years it's easy to stockpile a few of everything.... if you are big enough.

Dan

Your car was not made in china by a vendor contracted to make X number of that particular car model with those particular options, and whose commitment to it ceases with fulfillment of that order.

Yes, I understand that these little machines are made to a standard design by a small number of vendors. But I very much suspect you would have a great deal more trouble getting a machined and ready headstock casting for a "precision Mathews", or most of the other various import brands. Most likely you would even have trouble and delays (at least) getting a similar casting for most of the Grizzly products.

It is notorious, on this forum as well as many others, that it can be very difficult to get parts for chinese made products. Obviously this ONE, SINGLE, PARTICULAR, INDIVIDUAL product or product line, is an exception to the rule. That hardly justifies a shocked surprise that anyone would question the instant availability of any part wanted......

As you likely know, in general, parts are never considered by the bulk of product importers. If not aware of that, you clearly have never had a cheap chinese product go bad on you.... Normally the sole option at that point is to simply replace the entire unit, particularly because the price is so low that repairs cost more than a new one. Think most stuff from Wal-mart.... you bring back a bad one under warranty, they hand you a new one. (And the other maybe gets re-stocked, bit that is another story)

danlb
08-30-2018, 04:04 PM
Ok. I take that as the pessimist VS optimist viewpoint. No biggie. So far I have not run into any part for my mill nor lathe that are not available, so I would tend to be surprised when a part is NOT available.

Dan

Paul Alciatore
08-30-2018, 04:45 PM
He was probably working in mms. 0.41 mm = 0.016". And that sounds very reasonable for the job at hand.

As for his technique, he appeared to take the in-feed on the cross slide in fast chunks with long rests with on movement between them. A dead sharp tool, properly mounted on center, and with a more delicate in-feed technique would probably solve a lot of his problems.




I'd say that video is basically off topic since it is a demonstration of doing everything wrong and yet still able to get a usable result. After all, he could not even explain a measurement without getting it wrong.

Obviously a mistake. 41/1000 is more likely. Almost 1/2 inch for a ring is really out of bounds.

Dan

Mcgyver
08-31-2018, 11:44 AM
6x12 Grizzly, assuming i can find one. Nothing fancy, just something to learn on. Touching the bed itself was never part of the plan for this project, maybe scraping the headstock, tailstock and carriage to the bed but not the bed itself. Funnily enough thats the one movement axis i havent had trouble with, minus those blasted gibs. Tapered saddle gibs might make the project list...
!

I 100% get its for learning, I wouldn't in a million years recommend or be up for the effort involved in scraping things into a ground bed for a lathe like this other than the worthy pursuit of understanding how to do it. You're talking to a guy who scraped a mini mill X/Y set of castings just to have an example of dovetails for an article! Two things you get out of a project like you're considering that will make a person a far better craftsman, 1) knowing how to scrape which has all kinds of shop uses other than reconditioning, and 2) knowing how the fit and alignment of all the aspects of a machine tool come together to give its functionality ....and how both challenging and important fit and alignment is to performance.

Regarding tapered gibs, I'm guessing they would be a problem in that you wont have the room. You'd need to mill the female dovetail at the taper angle, and a tapered gib wants to be a little thicker than a strip gib. Is there enough meat left on the casting for that? Lots of well built machines a have straight gibs, they don't preclude great performance.....but tapered or straight, the rest of the dovetail has to be a proper fit with correctly bearing surfaces to get that good performance

epicfail48
09-21-2018, 04:35 AM
Little more work done on the lathe, before i start tearing down a surface grinder. Ordered in some angular contact bearings, the general consensus seems to be that theyre more suited for the lathe than tapered roller bearing would be because the angulars are a drop-in replacement and spin more freely. Picked up a new headstock casting from Grizzly as well, went ahead and swapped everything in.

Picture of all the bits and pieces:
https://i.imgur.com/64o0ej3.jpg

Old headstock torn down, with all the pieces that are getting swapped into the new one:
https://i.imgur.com/aGFXmQZ.jpg

And everything put back together for a test spin:
https://i.imgur.com/ruhH9If.jpg

Start to finish, about 3 hours. Didnt take too many pictures of the process, theres alread a lot out there. I followed the instructions from Arc Euro Trade, pretty easy to follow along. All told, dead simple to do, everything went together without issues and redoing the alignment was a lot easier now that the alignment doesnt shift with torque on the bolts.Got it aligned to about .001" over about 8" for horizontal and vertical, only took a few slim shims.

Played with it a bit, seems to run a mite smoother. Hard to tell how much of a difference the new bearings made, havent really put the lathe through its paces yet, but so far it looks promising. Theres less of a deflection issue, instead of having a .006" variance in dimension on a 1" cut, im seeing about .0002". Huge improvement in my book. Deflection seems to be much less of a problem too, i can finally run a boring bar and have it actually cut things without chatter.

I did also invest in some polished CCGT inserts for my indexable tools. The standard CCMT inserts didnt much like this lathe, the cutting force was just too high, but the CCGT ones just slide right on through without issue. Honestly they cut better than the HSS bits ive ground, so big win in my book. So far ive tried them in aluminium (duh), mild steel and 304 stainless, and had good results with everything. May not last as long as the ones meant for steel, but boy do they work better. Im actually not sure how much of the improvement in cut quality was from the bearing/headstock and how much the inserts were, all i know is that one of the new inserts in my boring bar sliced through metal like butter

Timo
09-21-2018, 05:39 AM
Perhaps it been mentioned already and I missed it but “You can’t make a silk purse out of a sow’s ear”.

J Tiers
09-21-2018, 11:09 AM
Perhaps it been mentioned already and I missed it but “You can’t make a silk purse out of a sow’s ear”.

No. but you damn sure can sew up the hole in the sow's ear purse...... Which seems to be the deal here.

Good work and good save on the machine.

The angular contact ball bearings may not be "better than" the tapered roller, but they will have less rolling resistance, and are easier to adjust correctly for low deflection. The difference in carrying capacity is of absolutely no consequence in that machine.

Timo
09-21-2018, 01:34 PM
Your free to pass your own judgment, but it's still a sow's ear, always was, and always will be. I'll credit him for his labor, but it's like spitting into the wind, never really works very well. No matter how hard you try. I'm all done for now, feel free.

epicfail48
09-21-2018, 01:52 PM
Your free to pass your own judgment, but it's still a sow's ear, always was, and always will be. I'll credit him for his labor, but it's like spitting into the wind, never really works very well. No matter how hard you try. I'm all done for now, feel free.

That's a point of view that has been, err, 'shared' repeatedly. My response has been the same throughout:

I'm not trying to make a silk purse. I have no intention of turning this thing into a Monarch. What I'm doing is making my tool work better inside my budget, and unless the condescending remarks are attached to a monetary contribution to buy a lovely hunk of american iron, well, spitting into the wind.

I'd say that my spitting into the wind improving this lathe stands a better chance of making something that works when compared to pointlessly attempting to tear people down because they can't afford what you can

J Tiers
09-21-2018, 02:29 PM
That's a point of view that has been, err, 'shared' repeatedly. My response has been the same throughout:

I'm not trying to make a silk purse. I have no intention of turning this thing into a Monarch. What I'm doing is making my tool work better inside my budget, and unless the condescending remarks are attached to a monetary contribution to buy a lovely hunk of american iron, well, spitting into the wind.

I'd say that my spitting into the wind improving this lathe stands a better chance of making something that works when compared to pointlessly attempting to tear people down because they can't afford what you can

F'n A right on.

it's easier to destroy than create. Perhaps that is why a number choose that option.

Mcgyver
09-21-2018, 02:55 PM
Your free to pass your own judgment, but it's still a sow's ear, always was, and always will be. I'll credit him for his labor, but it's like spitting into the wind, never really works very well. No matter how hard you try. I'm all done for now, feel free.

hmmmm....Last thread you commented on, you were chastising someone for being negative? I think Epic knows its not going to end up a Schaublin, but the fact is viewing a low cost machine as a set of castings and taking it from there you can for sure make it better, a lot better...AND he's doing this to learn and share what he's learning.


A frequent theme here is everyone saying they want more machining content here but when someone bothers to post machining conent they this sort of discouraging feedback. Guess why there aren't more threads about machining projects? The thread wasn't asking "should I do this or what is your opinion on me doing this", its "this is what I'm doing"

This happens all the time here. A machining thread gets hundreds of views but most of the comments are dumping on it or they just can't wait to tell you how you did it wrong and how they'd do it differently, whether help is asked for or not. This place would be better if instead of all that, those people put their energies into their own threads on what they are building and are up to.

Paul Alciatore
09-21-2018, 03:38 PM
It is also a skill that is acquired by actually DOING IT. I see nothing wrong with a person who has the time doing such work. It will greatly improve his skills.




I think fixing or re-working equipment to perform better is a skill few people have and fewer are acquiring. I tend to rather spend money instead of fix/upgrade and I'll have nicer tools, but at the cost of being less of a machinist as I'm just exercising my wallet and not improving my machinist skills in the process. Time is probably the most scarce so that and interest level are usually the deciding factors for me.

mattthemuppet
09-21-2018, 07:10 PM
Couldn't have said it better McGyver, nice work. That's also why I post less and less machining stuff. I even got told that I shouldn't post machining content in the "what did you do today" thread ffs.

Epic - nice work. You'll really like the ccgt inserts, especially on boring bars. The only flaw I've found is that the tips will bust off in steel if the cut stops suddenly (e.g. belt slip). Other than that they're great

epicfail48
09-21-2018, 10:14 PM
Epic - nice work. You'll really like the ccgt inserts, especially on boring bars. The only flaw I've found is that the tips will bust off in steel if the cut stops suddenly (e.g. belt slip). Other than that they're great

Already figured out theyre a bit delicate... Though, to be fair to the insert perhaps attempting to face off the little nub left by parting was asking a little much of it. Cant hardly fault it for that, even if i baby them on the depth of cut and the like, im still getting stuff done faster than with HSS, with a better finish to boot

garyhlucas
09-21-2018, 10:22 PM
Epic,
When you are ready to get a real lathe I’ll be happy to take this one off your hands!

J Tiers
09-22-2018, 12:45 AM
As I recently mentioned elsewhere, I started out with a Sears Craftman lathe made by "AA Products". Known to be nearly the worst "lathe shaped object" ever made.... But since nobody was around to tell me that I could not do stuff with it, that it was a POS that I ought to get rid of, I went ahead and made things with it.

Now, I DID eventually decide that it WAS a POS, etc, but at least I KNEW WHY I thought that. I had bought a Logan 10", and the difference between them was huge. Still, I used that machine and got the work done.

I expect that nearly any minilathe is a couple cuts above that "AA Products" machine, that there is nearly the same amount of difference between the AA and the minilathe as between the "AA" and the Logan.

epicfail48
01-06-2019, 04:13 AM
Another day, another project done on the lathe. The new bearings are doing quite well, and the lathe is noticeably stiffer and better running than it was before, but there was still a noticeable amount of deflection at the tool. Not enough to cause massive issues, but enough that operations requiring higher feed pressures, parting, using carbide inserts, tool post drilling, would still cause the carriage to shift enough to mess with things. Next stop on the list of improvements was to do something about the carriage gibs.

Now, on these lathes, the carriage gibs are screwed in place with 3 cap screws, and in between the cap screws are grub screws and the theory is that to adjust the tightness of the gibs, you adjust the grub screws to give the gibs the right distance from the bed ways, then lock the gibs down with the cap screws. Like many others, i figured that a solid shim would be a better option than those screws. First things first, disassemble carriage:
https://i.imgur.com/UsGKWaN.jpg

Off came the cross-slide and its joining bits, the leadscrew, and the thingy attached to the carriage thats used to move it whos name i cant recall. Apron maybe? Anyways, all this left me was the carriage base.

https://i.imgur.com/PyNvU91.jpg

Gibs and hardware disassembled and ready for work. First things first, plotting a plan of attack. Some people just use feeler gauges and keep building different stacks until they find the best fit. I wanted something a touch less hit-or-miss, so i broke out the micrometer to take some measurement. Heres what the carriage looks like where the gibs attach:
https://i.imgur.com/UORGbJU.jpg

To get the value of the shim ill need, im going to measure the distance from the top of the carriage to the bottom where the gibs mount, then take a second measurement from the top of the carriage to the bottom of the bed ways, where the gibs going to be riding. The difference between the 2 measurements gives me the value of the shim i need to bring the gibs where they need to to leave the perfect amount of free play. Take the measurements at the front and rear, right and left. My numbers ended up looking like this:
https://i.imgur.com/egGNcwL.jpg

Continued next post

epicfail48
01-06-2019, 04:18 AM
A quick test with some feeler gauge shims and the gibs clamped on to make sure the measurements track:[
img]https://i.imgur.com/T37WEOh.jpg[/img]

And from here there was a small detour. The shim thickness was bang on, but the carriage was still showing some excessive movement. I suspected that a chip, ding or whatever was interfering with the mating of the bed ways to the slot in the carriage, so to take care of everything at once i decided to lightly lap the carriage to the bed ways. Some 400 grit sandpaper spray-adhesived to the ways and a few quick strokes took care of the problem:
https://i.imgur.com/jKmz9bB.jpg

Minimal metal removed, and whatever was causing the tipping issue was no longer a problem. Reconfirmed with the feeler gauges and the clamps to make sure that movement was good, and then off to milling out the material for the permanent shims. The donor material was some steel recovered from the handrail of an old treadmill, brought to rough size on the mill then finish ground to dimension on the surface grinder:
https://i.imgur.com/JZF8sO1.jpg
https://i.imgur.com/040ckjC.jpg

Continued next...

epicfail48
01-06-2019, 04:30 AM
Once i had the 2 shims to thickness, i needed to get the bolt through the shim somehow so i could actually get the gibs installed on the carriage. The way that i saw it, i could spend a lot of time precisely locating the holes, or i could spend a minute and a half cutting a slot with an angle grinder to let the bolts pass though. I went with the second option:
https://i.imgur.com/rDBvvxG.jpg

Doesnt look pretty, doesnt need to, it works and thats what matters. For funsies, i also slapped the gibs themselves on the surface grinder, just to get a flat face for them to run on. From here, it was just reassembly, relatively painless. I did manage to overshoot the target dimensions on the front shim by about .002", im still learning how to operate the grinder. A few bits of shim stock fixed that right up and let the carriage run plenty free, while still keeping everything tight. Here she is all reassembled and ready to work:
https://i.imgur.com/zDPwVKg.jpg

Such a simple mod, such a world of difference. Everything combined lead to a much, much better fit between carriage and bed, and now rigidity is something i have rather than something i use as a curse. Not 'real' lathe rigidity of course, but rigid for its size. Total free play in the carriage movement up, down and rotational is pretty undetectable, which led to the tool staying where it needed to be rather than twisting off course. The most noticable difference was in parting; the lathe could technically part of things before, but the cut was hardly clean and the chips and chatter were pretty nasty. Now though, the blade stays where it needs to, doesnt wiggle around, and i can get nice, curly chips parting stainless without having to baby the cut.

Other areas were improved as well, my carbide insert tools actually cut well with steel inserts, and i can put some actual feed pressure on the tool post drill chuck without forcing the carriage to rotate and bend the drill. I cant attribute all the difference to the improvement to the gibs, but between the better bearings, improving the gib fit and lapping the carriage to the ways this lathes functionality has been massively improved.

Next up im tackling the tailstock alignment, ive always managed to get front-to-back aligned perfect, but the quill centerline sits .010" higher than the spindle center line. One of these days ill toss the tailstock base on the mill/grinder and take off the material to get everything perfectly aligned

J Tiers
01-06-2019, 09:34 AM
Some of that is really a job to be done by "scraping", but you got it done.

Good ingenious use of what you have.

RB211
01-06-2019, 11:06 AM
Question is this... With the amount of work you did, have you noticed an improvement? Also, ThisOldTony replaced the ball bearings in the headstock with tapered roller bearings. No point in doing any of this if you don't get any gains. He seemed to think there was a difference. Don't ask why a "lathe" even ships with non angular contact ball bearings or better?

GadgetBuilder
01-06-2019, 01:18 PM
It would be worthwhile to verify that bed thickness is constant from headstock to tailstock, this is a fairly common issue with these machines. Cheap and reasonably easy to deal with, see:
http://warhammer.mcc.virginia.edu/ty/7x10/vault/Lathes/7x10-7x12-Projects/TaperedSaddleGibs/Bedways.html

John

J Tiers
01-06-2019, 01:56 PM
...

Such a simple mod, such a world of difference. Everything combined lead to a much, much better fit between carriage and bed, and now rigidity is something i have rather than something i use as a curse. Not 'real' lathe rigidity of course, but rigid for its size. Total free play in the carriage movement up, down and rotational is pretty undetectable, which led to the tool staying where it needed to be rather than twisting off course. The most noticable difference was in parting; the lathe could technically part of things before, but the cut was hardly clean and the chips and chatter were pretty nasty. Now though, the blade stays where it needs to, doesnt wiggle around, and i can get nice, curly chips parting stainless without having to baby the cut.

Other areas were improved as well, my carbide insert tools actually cut well with steel inserts, and i can put some actual feed pressure on the tool post drill chuck without forcing the carriage to rotate and bend the drill. I cant attribute all the difference to the improvement to the gibs, but between the better bearings, improving the gib fit and lapping the carriage to the ways this lathes functionality has been massively improved.

...

Looks like yes he does notice it......

epicfail48
01-06-2019, 02:37 PM
Some of that is really a job to be done by "scraping", but you got it done.

Good ingenious use of what you have.

Its still on the project list to go through and scrape the ways of the cross and compound slides, but I keep getting busy with other projects. The bed I don't think I'll be touching, though I do agree that scraping the bed and ways in the carriage in would be a good idea. Outside my skill level at the moment though


Question is this... With the amount of work you did, have you noticed an improvement? Also, ThisOldTony replaced the ball bearings in the headstock with tapered roller bearings. No point in doing any of this if you don't get any gains. He seemed to think there was a difference. Don't ask why a "lathe" even ships with non angular contact ball bearings or better?

Very, very noticeable. No one mod by itself made a huge difference, the bearing replacement, for example, gave a slight improvement, but stack them on top of each other and its night and day. As mentioned, I can actually part things off without a chattering nightmare, and my carbide insert tools aren't shifting around to the point they break tips anymore. More rigorous testing is needed, but even the brief time I've spent playing with everything after the mods really proves the worth


It would be worthwhile to verify that bed thickness is constant from headstock to tailstock, this is a fairly common issue with these machines. Cheap and reasonably easy to deal with, see:
http://warhammer.mcc.virginia.edu/ty/7x10/vault/Lathes/7x10-7x12-Projects/TaperedSaddleGibs/Bedways.html

John

I actually had measured the thickness, though I can't for the life of me remember how that went. I want to say it was withing a few thou across the length, though I could be talking out of a different part of my anatomy on that one. I did lightly run a file along the underside, just to take out any high spots. There's still a few ever so slightly tight spots in the travel, so the ways aren't perfect, but its enough for me to live with

epicfail48
01-09-2019, 06:22 AM
Another day, another improvement to make on the mini-lathe. This time, Im focusing on this:
https://i.imgur.com/Sdga3IV.jpg

Yup, the tailstock. Ive known for a while that ive got issues with this, mainly that the centerline of the tailstock sits higher than the centerline of the headstock. Tends to make drilling a problem, and creates some interesting problems with a center. So, for this next part im going to get that fixed to get the tailstock quill perfectly in-line. First up is a lot of measurement, i want to get this exactly right and plan everything out bit by bit, so i need to know exactly what im working with. Lot of pictures, so im going to split this up into several posts to explain my process

epicfail48
01-09-2019, 06:31 AM
First off, i want to check the alignment of the tailstock as-is. Cant fix something if you dont know what the problem is after all. First up, i want to check parallelism with the ways, to make sure that my drills are actually fed straight into the piece. To do this, im going to extend the quill (ram?) of the tailstock as far as it goes, lock the quill, lock the tailstock to the bed, then use a test indicator on the carriage to sweep the quill. Indicator is zeroed on the top of the far end of the quill:
https://i.imgur.com/Rh8Cg6k.jpg

And then cranked to the rear of the quill:
https://imgur.com/IGqmZgP

The rear of the quil dropped by .003" when compared to the front, so that axis is out a bit. Repeat with the side of the quill, to determine misalignment in the horizontal direction:
https://i.imgur.com/f8jpxUd.jpg
https://i.imgur.com/FXOeWvy.jpg

Slightly better at .001" read misalignment. So, alignment with the ways is just a touch off, but not horrible. Next up is to check the alignment of the centerline

epicfail48
01-09-2019, 06:43 AM
So, to check the alignment of the centerline, im going to do what i find to be the best method, and thats to fit a test indicator on a bar held in the headstock and sweep the taper of the tailstock. If im perfectly aligned, i should get the same reading on all points of the taper. First, the horizontal direction, front to back if you were using the lathe. Zerod at the front:
https://i.imgur.com/lTHw2uy.jpg

And rotated 180 degrees to the rear:
https://i.imgur.com/5MQeVJw.jpg

So, the tailstock is .005" too close to the front. Thats easy enough to fix, back-to-front alignment is built into the tailstock after all. Next we need to check the vertical alignment, and this is already known to be off. Same process, zeroed at the bottom:
https://i.imgur.com/jzwUMVc.jpg

And rotated 180 degrees to check the top:
https://i.imgur.com/f3l3lhR.jpg

Indicator is reading that the taper is sitting .005" higher than the centerline of the lathe, which i found odd. Last time i checked it was .010" higher, but that was before i changed the headstock casting. New one sits higher than the old one i guess. Anyways, now ive confirmed what i need to fix, the question is how. Theres 2 methods i can use for this, i can either make the headstock taller or i can make the tailstock shorter. Making the headstock taller would require me to dismount it and shim the entire thing up to match the height of the tailstock. Im not a fan of that idea, removing the headstock is quite the chore to do, and im not fond of the idea of the headstock resting on a stack of shims. That just leaves option 2, making the tailstock shorter, and thats the move im going to make. It doesnt seem like its a very common move, most people seem to opt for the headstock route with the theory being that as the tailstock base wears they can remove shims from the headstock to keep things in line, but id prefer adding shims to the tailstock for that. Plus, i get to play on the surface grinder this way.

Before anything hits a tool though, still need to do more measurement. Onto the next post!

epicfail48
01-09-2019, 07:00 AM
First things first, i want to establish exactly how much higher the tailstock is so i know how much needs to come off. I know i already checked this with the test indicator, but personally i see test indicators as a way to get a relative dimension for comparison, whereas i want an absolute dimension for this. In my mind the question is using a DTI to tell if part A is higher than part B, versus using a micrometer to measure the exact thickness of part A.

Now that thats out of the way, im going to start by finding out the height of the center of the axis of rotation. The way im choosing to do this is to chuck up a piece of scrap, but it to run true, pick up the height of said piece from the ways with a height gauge, then subtract half the diameter of the part from that measurement. Should give me the exact height with the minimal amount of work. Picking up the height of the piece:
https://i.imgur.com/zfC8roj.jpg

Followed by some math. Yes, i wrote this all down on top of the compound slide. Couldnt find a post-it
https://i.imgur.com/uLruju6.jpg

Up top is the diameter of the piece i turned, .4848". Clearly, i was not shooting for a precise dimension, just getting the piece to run true. Under that is the height from to the bed to the top of the piece, 3.804", minus half the pieces thickness, .2424, giving me the precise height of the centerline, 3.5616". Weird number, but matches up with the advertised 7 inch swing of the lathe.

Next, i need to repeat this process with the tailstock. Problem is, i cant just turn a piece to be concentric with the tailstock axis the same way, because the tailstock doesnt spin. I could hold a gauge pin in the drill chuck and use that to measure, but then id be bringing in possible runout of the chuck. A collet would work better, but i dont have anything of the sort that would fit the tailstock. In the end, i chose to indicate off the outside of the quill. I did measure the diameter, its consistent through its length and is as straight as i can measure, and im choosing to operate under the assumption that the taper is concentric with the OD. Same process, pick up the height from the bed to the top of the quill:
https://i.imgur.com/uYHNdfn.jpg

Then math:
https://i.imgur.com/V9ABj9F.jpg

Again, could find a post-it. If you cant make that out, the tailstock quill measured .8648", bed to top was 3.9985", which left the centerline at 3.5661". So, if the tailstock centerline is 3.5661" and the headstock is 3.5616", that leaves the tailstock needing to come down by .0045" to be in line. Time to plan that one out!

epicfail48
01-09-2019, 07:28 AM
Luckily for my plans, the tailstock on these lathes is actually 2 pieces, there the main part that hold the quill, and a base that actually contacts the bed that the main bit is bolted to. My plan at this point was to take the quill apart, take the metal i needed to off the base, then sit back with a drink after a quick and easy job. First things first, some disassembly which im not going to bore you with the details of. Millions of people have already gone over how to disassemble the tailstock on a mini-lathe already. All that off camera, so heres the workpiece:
https://i.imgur.com/AYZ02yh.jpg

Yikes. This just got a lot more involved of a project. My initial plan was to just stick the part on the surface grinder and take off .0045" from the 2 bearing surfaces That plan went right out the window as soon as this touched the surface plate and turned itself into a see-saw. I dont think that "flat" translates very well into whatever language the guy making this part spoke. Quick flip the check out the underside:
https://i.imgur.com/BcAzqcV.jpg

Didnt know you could use a chainsaw to machine parts. This is honestly the first time ive been flat out disappointed with one of the parts of this lathe. For the price i dont expect much, but still, the v ways arent square, somehow the flat faces of the v arent straight, the entire base is out of flat, the surface finish on all machine parts doesnt deserve to be called a finish or even machined, its just a mess. Really, after measuring this im not even going to try to fix is, for the 4 thou i have to take off the height theres not even enough material to take off to fix some of the issues. Ive got a hunk of durabar in the basement, im just going to take off a slab of that and make a new base, ill need to pick up a 90 degree chamfer mill but i cant possibly do any worse than this.

Before i dive into all that though, i want to check the main part of the tailstock to make sure all of its important machined surfaces are in-line with each other. The only really important ones i see are the pads where the main casting meets the base piece, and i need to make sure those are in-line with the quill. To do this im just going to set that main casting on the surface plate, then sweep the quill top with the DTI on a surface gauge. Zeroed at the far end:
https://i.imgur.com/d44fIjM.jpg

And then checked at the close end:
https://i.imgur.com/vhGQMQS.jpg

So, the contact points on the main casting are out of line with the quill by about .002" over the length. Not horrible, but it still like to take that out. The leading idea for this is to throw the piece in the mill vise, align it so that the quill is perfectly inline with the mills X axis, then remachine the contact surfaces. That way, when i make the new base plate i know that as long as the contact points on the baseplate are parallel to the ways, the tailstock axis will be too.

Thats all for now, ill get to work making the new base piece at some point. Need to source a chamfer mill first, although i am considering just grabbing a v grooving router bit instead and using that since theyre more commonly available. Ive had decent results using router bits for milling purposes in the past, no reason it wouldnt work for this. As an added bonus, id be able to make the base immediately, rather than waiting for something to show up in the mail. I think ive got a router bit on hand, and if not i can run to Grizzly and grab one of those today.

chucketn
01-09-2019, 08:54 AM
I've been quietly following your progress, and WOW! I have owned a MicroMark 7x14 for 18 years and have enjoyed using and learning with it. I would love to have the skills to do what you are doing.
BTW, the last 2 pictures in your last post don't show for me...
Ignore the naysayers! Keep on truckin'.

epicfail48
01-09-2019, 09:06 PM
I've been quietly following your progress, and WOW! I have owned a MicroMark 7x14 for 18 years and have enjoyed using and learning with it. I would love to have the skills to do what you are doing.
BTW, the last 2 pictures in your last post don't show for me...
Ignore the naysayers! Keep on truckin'.

If any of this took skill i wouldnt be doing it...

In all seriousness, none of the mods ive shown so far have required anything beyond the basics of machining, its mostly been a lot of measuring. Even making the new baseplate for the tailstock is going to be simple, though theres going to be a lot of milling involved

garyhlucas
01-09-2019, 10:30 PM
Knowing what to measure and how to measure is more than half the knowledge of being a machinist in my book.

mattthemuppet
01-10-2019, 11:04 PM
quick tip for the long run - mill/ grind some oil grooves in the bottom of the carriage and put in a couple of GITs cups for way oil, then make some way wipers. Being able to get way oil to the sliding surfaces will let you run the gibs tighter and still have smooth movement = less chatter and wear. Made a noticeable difference on my Atlas.

markx
01-11-2019, 03:13 AM
I dont think that "flat" translates very well into whatever language the guy making this part spoke.

This looks rather familiar :D The problem with these types of machines seems to be that the visible parts on first glimpse are rather well machined and seem to possess at least some degree of functionality (like the main bed and ways), but all of the hidden parts like underside of tailstock, the cross slide and compound are just in a horrible state regarding flatness. I've had blind luck with my unit: despite the hacksaw machining job on the hidden parts, the machine has actually performed rather well over long years. So I've not really done much to rectify the uneven surfaces, just the occasional tightening and some adjustments. I can not justify the amount of work involved in a full scale improvement job. On a bigger more rigid machine it would make sense to me, but on these little ones I'm not up to it really.
I do not mean to say in any way that one should not go through with all of this....it is a great project that I follow with interest and there is much to be learned from these activities. So keep up the progress and let us know :) !

RB211
01-11-2019, 05:27 AM
Million dollar question. After putting all of this work into the lathe, would you do it all over again? Or buy a slightly larger lathe that was ready to go, like the 8xXX series?

markx
01-11-2019, 08:23 AM
I guess this more of a learning curve enhancement and recreational topic than actual intention to improve the performance of this little machine to such an extent as to be worth the effort :)

For example I rebuilt an old rotten BMW once for similar purposes and had a lot of fun doing it (ended up driving the thing for over 120000km too). In retrospective it was a fun and educational project, but hardly worth the work and effort I put into it. In retrospective I would not find it in me to do it again.

epicfail48
01-11-2019, 02:32 PM
This looks rather familiar :D The problem with these types of machines seems to be that the visible parts on first glimpse are rather well machined and seem to possess at least some degree of functionality (like the main bed and ways), but all of the hidden parts like underside of tailstock, the cross slide and compound are just in a horrible state regarding flatness. I've had blind luck with my unit: despite the hacksaw machining job on the hidden parts, the machine has actually performed rather well over long years. So I've not really done much to rectify the uneven surfaces, just the occasional tightening and some adjustments. I can not justify the amount of work involved in a full scale improvement job. On a bigger more rigid machine it would make sense to me, but on these little ones I'm not up to it really.
I do not mean to say in any way that one should not go through with all of this....it is a great project that I follow with interest and there is much to be learned from these activities. So keep up the progress and let us know :) !

Weirdly I've never actually had much of a problem with lubrication. Wipers and oil cups are on the to do list, but so far I've no had an issue just squirting some way oil on. In all honesty, the lathe worked just fine as-is when I got it, there's a reason I haven't been upset about some of the shoddy machining, despite the shoddiness it gets the job done. I just wanted the job done a tiny bit easier, hence this thread.


Million dollar question. After putting all of this work into the lathe, would you do it all over again? Or buy a slightly larger lathe that was ready to go, like the 8xXX series?

Million dollar answer; an 8x22 lathe I can afford would be in the same initial state as this one, so yeah, I would do it all over again. I have no trouble spending time to save money, I have more of one than the other. It'll be a very long while before I have to worry about it though, the 7x12 work envelope fits nearly everything I need to do


I guess this more of a learning curve enhancement and recreational topic than actual intention to improve the performance of this little machine to such an extent as to be worth the effort :)

For example I rebuilt an old rotten BMW once for similar purposes and had a lot of fun doing it (ended up driving the thing for over 120000km too). In retrospective it was a fun and educational project, but hardly worth the work and effort I put into it. In retrospective I would not find it in me to do it again.

Dunno that I'd view it that way, as far as I'm concerned the improvements have already been worth the effort. I've spent a few hours of time turning an okay tool into a good tool

chucketn
01-11-2019, 02:43 PM
Good job, Epic! What's next?

epicfail48
01-11-2019, 06:41 PM
Good job, Epic! What's next?

Whelp, first Im still in the process of making the new base for the tailstock. Had to order in a chamfer mill, so thats briefly on hold, but once i have that in-hand ill be doing a writepup on making that part and finishing the tailstock alignment.

After i get the tailstock sorted out, i havent decided what the next tweak is going to be. Wipers and oil cups for the carriage are tied for first, with the other option being a camlock system for the tailstock. Unrelated to the lathe, ive also been making some tweaks and improvements to mini mill, in the same vein as what ive been doing to my lathe

nickel-city-fab
01-12-2019, 02:58 AM
Just wanted to say to Epicfail, thanks for the inspiration. I'm kinda in the same boat. Got some decent machines at work but not so much at home. Not much money but some free time on the weekends. If you got time, you spend time; if you got money, you spend money. Usually its just a little bit of both, combined with some ingenuity.

RB211
01-12-2019, 03:47 AM
When I said 8xXX, was referring to the Horror Fright 8x12(Lathe Master 8x14), not another Sieg product. Catch it when it is on sale, plus another 20-25% off coupon.

epicfail48
01-12-2019, 04:16 AM
When I said 8xXX, was referring to the Horror Fright 8x12(Lathe Master 8x14), not another Sieg product. Catch it when it is on sale, plus another 20-25% off coupon.

You mean the Seig C4 with Harbor Freight branding? :p

Honestly, ill probably skip over that, ive already decided that my next lathe is going to be one of the larger benchtop ones, somewhere in the 10x22 range or a touch bigger. Bells and whistels, power cross feed, quick-change gearbox, the fun bits. Thats way down the road though, and one of the reasons im enjoying tweaking this mini-lathe is because im also building the skills needed to work on one of those larger machines and get it trued up. Opens up the market a bit more, and saves money to boot. My price range will likely never encompass the old American high-grade iron, or even a higher end import. If i can take a mid-low range import and throw some elbow grease at it, well, that i can afford. Can also go for one of the old, slightly beat up bits of American iron and know that no matter the problem, i can fix it

RB211
01-12-2019, 04:20 AM
You mean the Seig C4 with Harbor Freight branding? [emoji14]

Honestly, ill probably skip over that, ive already decided that my next lathe is going to be one of the larger benchtop ones, somewhere in the 10x22 range or a touch bigger. Bells and whistels, power cross feed, quick-change gearbox, the fun bits. Thats way down the road though, and one of the reasons im enjoying tweaking this mini-lathe is because im also building the skills needed to work on one of those larger machines and get it trued up. Opens up the market a bit more, and saves money to boot. My price range will likely never encompass the old American high-grade iron, or even a higher end import. If i can take a mid-low range import and throw some elbow grease at it, well, that i can afford. Can also go for one of the old, slightly beat up bits of American iron and know that no matter the problem, i can fix itIt's NOT a C4. Different manufacturer. I own the Lathemaster 8x14(same lathe) that I am going to convert to CNC.
It's a serious step up in terms of rigidity, fit and finish, but has fewer bells and whistles.
But yes, I too would hold off for a larger lathe.

epicfail48
01-14-2019, 01:57 AM
Whelp, went to get to work on the new tailstock base tonight. Was getting the block-o-iron set up in the mill vise, checked the vise tram, went to tighten down the clamps just to be sure and this happened:
https://i.imgur.com/VSdolNM.jpg

More torque on a smaller bolt on the other hold down didnt cause any new issues. Dont use cheap t-slot bolts... Shouldve known better than to trust the ones that came with the vise. Throws a spanner in the works, and puts things on hold until i can get to grizzly and get some proper t-slot nuts on Tuesday. Thought about making some, but thats somewhat difficult when you cant hold things on the mill table!

J Tiers
01-14-2019, 02:34 AM
A hacksaw and a file should suffice..... Bootstrap your way up to what you need rather than waiting...

reggie_obe
01-14-2019, 10:02 AM
[QUOTE=epicfail48;1216402

More torque on a smaller bolt on the other hold down didnt cause any new issues. Dont use cheap t-slot bolts... Shouldve known better than to trust the ones that came with the vise. Throws a spanner in the works, and puts things on hold until i can get to grizzly and get some proper t-slot nuts on Tuesday. Thought about making some, but thats somewhat difficult when you cant hold things on the mill table![/QUOTE]

Proper T nuts, stud and other clamp hardware: Jergen: Gibraltar, Teco, etc., avalable at MSC, Grainger, McMaster, etc.

Dan_the_Chemist
01-14-2019, 11:52 AM
YouTuber (and HomeShopMachinist lurker) This Old Tony has just started some videos on rebuilding a LSO into a real tool. Two of the things he has done so far include bolting it to a heckova strong table, and replacing the cheap spindle bearings with some better ones. He reports a significant improvement so far.

https://www.youtube.com/watch?v=05vUCdzhoe4


https://www.youtube.com/watch?v=05vUCdzhoe4

The second video is linked here:
https://www.youtube.com/watch?v=HYOgmhpBUJs

RB211
01-14-2019, 12:57 PM
You know, it is funny, I would think threads like this would drive people away from buying a mini lathe.

epicfail48
01-14-2019, 02:49 PM
You know, it is funny, I would think threads like this would drive people away from buying a mini lathe.

Yes, you've been very vocal about your disapproval of this entire endeavor. I have to ask, is there a reason you keep throwing petty jabs up? Do you have stock options in every machinery company except for Seig?

My response will remain the same to every one of these little barbs you throw up about how horrible this class of machine is; unless the insults come with a cash donation, probably best to keep them to yourself

danlb
01-14-2019, 03:40 PM
You know, it is funny, I would think threads like this would drive people away from buying a mini lathe.

Why? He said that even the rough tail stock milling did not impact the functionality. The work he was doing is not much different that what is proposed for people buying 50 year old 9 inch Southbends.

J Tiers
01-14-2019, 03:41 PM
Cold......

The question is, of course, concerning buying a new machine, and having to rebuild it, re-scrape it, etc to make it into something useful ("useful" being a "somewhat elastic" definition, depending on personal opinions). Some folks consider that you are permanently turned into a clueless and stupid "home shop Harry" by ever touching the tip of your finger to a minilathe.

it does seem as if one could find a better starting place, but the minilathes are cheapish and available. Their one problem is an entire lack of the more useful features, depending on which importer specified the features. Most seem to have no back gear, some have no QCGB, etc. Others of the features are just cheap, clumsy and/or inaccurate.

With all that, there is absolutely nothing wrong with a rebuild. Just look at it as an inexpensive set of castings..... You can pay more for a Stuart models casting set for a tiny steam engine, at least the lathe is useful.

J Tiers
01-14-2019, 03:46 PM
Why? He said that even the rough tail stock milling did not impact the functionality. The work he was doing is not much different that what is proposed for people buying 50 year old 9 inch Southbends.

In some ways, yes.

But the Southbend was, when new, a good accurate lathe including many of the features of larger machines. It has to be admitted that whhen new, the minilathe is often poorly fitted, may lack many of the usual features, and in general is never of the SB quality level unless and until rebuilt. (as Doc says in the next post, that may not be a stopper for many folks, who do not NEED any more of a machine than what a mini is out of the crate.)

One can be reasonably sure that the SB will be a nice machine when completed. The minilathe will always retain some of it "sow's ear" characteristics, since they are baked-into the design (depending on which importer selected the features and options)..

Which is not a reason to not do the rebuild, just something to remember when it comes to the expectations for the result.

Doc Nickel
01-14-2019, 03:53 PM
You know, it is funny, I would think threads like this would drive people away from buying a mini lathe.

[cracks knuckles]

Let's go down the list, shall we? Try and keep up

1) Not everybody NEEDS a big lathe. Believe it or not, there are people out there that aren't machinists, and only need to make the occasional, relatively low-tolerance part for a another project, like a homemade 3D printer.

2)Not everybody has the ROOM for a "proper" lathe. I spent a couple of years living in an apartment- I'd have killed for a mini lathe, because it would have been better than what I had, which was no lathe at all.

3) Not everybody needs a BIG lathe. Look at how many people here on this board just make what are essentially model parts. If most of the pieces you make are parted off of 1/4" bar stock, you don't really need a 10" Southbend or a Dean, Smith & Grace. Look at the work Clickspring does with a Sherline.

4) Not everybody needs a PROJECT lathe. Despite Tony's video and the local threads, the minilathes are generally usable more or less out of the box. They can often stand some tweaking, but can generally be used with minimal effort. Not everyone wants to buy a scrapped and salvaged lathe, and spend the next eight months stripping rust, reboring bushings, and scouring eBay for hart-to-find replacement parts.

5) Not everybody has a supply of LOCAL lathes to choose from. Speaking personally, I live in a machine-tool wasteland. Home-shop sized machines are nearly nonexistent. Apart from two Smithy or Shopmaster style "3-in-1" combo machines, I can count on the thumbs of one hand how many HSM-appropriate lathes cave appeared for sale in my area in the last three years.

6) Not everybody can AFFORD a 'real' lathe. A mini can be had for $500 and shipped for less than $100- often free in some cases. Something the size of a Logan, Southbend or Sheldon, with any accessories at all, might cost $500 just in shipping.

7) Not everybody wants to INVEST in a 'real' lathe either. There's lots of people out there that, inspired by local Maker Spaces, Tech Shops and YouTube videos, would like to buy their own machines to start playing with. But lacking solid knowledge, aren't really interested in investing $5,000-$8,000 and 50% of their garage space to a Bridgeport and a Heavy 10. A $500 mini lathe and a $500 mini mill are excellent 'stepping stones' to get a user started.

8) Not everybody needs a WORKING lathe. In Tony's case, if you haven't seen his video, he's planning to convert that mini to a CNC lathe. Would you rather he chop up an otherwise-good Southbend? In my case, I converted my otherwise-in-excellent-shape Logan in order to get a CNC lathe, but I made sure I didn't permanently modify the lathe itself- no new drilled holes or cuts- so it can be turned back into an engine lathe once I can afford a real CNC lathe.

Do I need to go on? When I launched my business, I bought a new Grizzly 9x20, because literally nothing else was available. It's not that I didn't like the local selection, there WAS NO local selection. There's still no local selection. But that Grizzly worked, I was able to make several tens of thousands of dollars' worth of product with it, and I was able to sell it for most of it's original cost when I upgraded.

You don't need a mini? Fine, no problem there. I don't either, other than I'm kind of keeping an eye open for a cheap, well-used one that I can use as basically a "polishing lathe" and not have to worry about getting dust and grit on.

But there's thousands out there that do, and are glad to have them. I seriously wish they'd been available back in the days I lived in an apartment.

Doc.

RB211
01-14-2019, 04:31 PM
Yeh, it wasn't a jab. If I was looking to buy a new small lathe, and looked at all the work you put into it, I would be scared off from buying a mini-lathe. That was the point of it. I think you do excellent work. Doc, nothing to do with lathe size, I like Taig stuff after all!
My point is that the mini-lathe has problems. The slightly larger 8x12 that HF sells is a superior lathe and not a Sieg product.
Will the work fit on a Taig? Great, it's made in the USA, and cheaper!

epicfail48
01-14-2019, 06:49 PM
Yeh, it wasn't a jab. If I was looking to buy a new small lathe, and looked at all the work you put into it, I would be scared off from buying a mini-lathe. That was the point of it. I think you do excellent work. Doc, nothing to do with lathe size, I like Taig stuff after all!
My point is that the mini-lathe has problems. The slightly larger 8x12 that HF sells is a superior lathe and not a Sieg product.
Will the work fit on a Taig? Great, it's made in the USA, and cheaper!

And the people who are scared off of buying a mini-lathe by reading a compilation of completely unnecessary modifications, that starts off with "it works good as-is, i just wanted a tiny bit better" probably wont be too big into the hobby once they start. I may be a bit biased, but i think that even for the several people this thread may scare off, its worth far more to the people who do get one of these lathes and want inspiration for what they can do to make the operation that tiny bit better.

That HF lathe you keep bringing up retails for $999.99. The Grizzly G8688 retails for $595.00. Yes, HF has coupons, and yes, to you the HF may be a better machine, but none of that changes 2 simple facts; 1) one machine being better doesnt make another machine bad, and 2) Not everybody wants to or can justify that extra $400, especially not on whats likely their first tool. Heck, i picked up this lathe for $100 at a tent sale, and even that was a lot for me to part with at the time, but you know what? May have been the best $100 ive ever spent, because its made me that much back and more, in its stock state.

If all youre going to do is continue preaching about how something else is so much better that this is all a stupid waste of time for me and it isnt worth the effort, and the comments dont include a $1000 paypal transfer for me to go buy the lathe of your choosing, kindly take it somewhere else. Funny part is even if i did have that HF lathe, id probably be doing all the same things to it anyway. Everything that ive done has been correcting cost-cutting measures and quality control slipups, if a product sold by Harbor Freight isnt afflicted by that, ive got a bridge in Brooklyn to buy

reggie_obe
01-14-2019, 06:59 PM
Why not improve the tailstock base, instead of starting a square one? The bottom is twisted, is the top twisted similarly? If not couldn't you use the top as a reference to make the bottom flat and parallel to the top?

epicfail48
01-15-2019, 05:21 AM
Why not improve the tailstock base, instead of starting a square one? The bottom is twisted, is the top twisted similarly? If not couldn't you use the top as a reference to make the bottom flat and parallel to the top?

Lack of material to fix how severe the issues were. The centerline of the tailstock only measured .005" higher than the centerline of the headstock, by the time i flattened everything up, trued up the mating surfaces and got the overall millwork to a finish id approve of, id have to shim the tailstock back up into line with the headstocks centerline. Overall, give that id have to make most of the same machining steps to rework the old on anyways (remachine the prism, grind both sides for a better finish and parallelism, machine the top to bring the tailstock perfectly into alignment), it just made more sense to start from scratch. I already had the material on-hand, thanks to a big old bar of Durabar i have in the basement, and it seemed like a good project to challenge myself with.

1200rpm
01-15-2019, 06:40 AM
be easier to make/adapt a whole new tailstock....THAT would be an improvement.

CCWKen
01-15-2019, 07:27 AM
If all youre going to do is continue preaching about how something else is so much better that this is all a stupid waste of time for me and it isnt worth the effort, and the comments dont include a $1000 paypal transfer for me to go buy the lathe of your choosing, kindly take it somewhere else.
Ah, don't take this place too serious. We all like spending other people's money. :D From awls to Z-bars, you could go broke trying to follow everybody's suggestions. It all boils down to what you feel comfortable with spending and the effort you put into your work. Similar to woodcraft--The best stuff made was probably done with an axe and pocket knife. You don't need a shop full of expensive tools to have fun. It's a hobby! If it sometimes makes money, that's a bonus.

Keep up the great work!

RB211
01-15-2019, 08:07 AM
How close do you live to Skaneateles, NY? I'll give you a South Bend 9c, only to you.

Mcgyver
01-15-2019, 10:27 AM
You don't need a shop full of expensive tools to have fun.

This.

A combo of time, bit of luck, bit of trading, bit of self taught prowess and a lot of work has given me a nice shop. But you know, while I love having all the kit and building it out has been a quest in itself, I got just as much enjoyment with that first lathe and mill 27 years ago.

RB, that is a nice offer.

epicfail48
01-15-2019, 05:18 PM
be easier to make/adapt a whole new tailstock....THAT would be an improvement.

Did consider that actually, but really the rest of the tailstock is in good shape. Quill is smooth, no play to be identified, everything works fine, it was just this base piece that was a mess. Making an entirely new tailstock would be a fun project, but ultimately unnecessary, plus it would go against the spirit of what im trying to do, and thats to get the most improvement from the least amount of work. Building a new tailstock would probably be a slight improvement, but not enough to justify the massive amount of work


How close do you live to Skaneateles, NY? I'll give you a South Bend 9c, only to you.

Springfield Missouri unfortunately, but i appreciate the offer!

epicfail48
01-16-2019, 07:05 AM
Day off from the day job and a quick to Grizzly proved fruitful for me. Got the vise situation worked out with some t-slot nuts thatll work until i get around to ordering in some 4140ph to play with and make new ones, so i could actually hold things to my mill again. Got the hunk-o-iron clamped up, took a few minutes to make sure that the ground bottom of the block was perfectly in-line with the movement axes. Everything was pretty uneventful, milling went about as youd expect. The chamfer mill i used to cut the prism slot worked great, cut clean and smooth, plus the solid carbide blasted through things a lot faster than i expected. Anyway, picture time:

https://i.imgur.com/8I08Et0.jpg
Still in the vise, with the surfaces all freshly milled.

https://i.imgur.com/pTcBm4k.jpg
Close up of the prism channel. Left a beautiful finish, not ground by any means, but not the chainsaw mess that was the original part. Its actually well enough im considering recutting the prism channel in the carriage to improve the finish...

https://i.imgur.com/5ln6ACI.jpg
The moment of truth, test-fitting the new base to the bed ways. I was very, very happy with the fit. The channel looks like it has gaps, but thats just the chamfer on the edges casting a shadow, the actual fit is spot-on

https://i.imgur.com/N6ogcqX.jpg
Not necessary at all, but i decided to blue up the lathe bed to see just how good contact was. Little heavy on the blue, but thats okay, i wanted to know where general contact was, not scrape for a bearing surface. As you can tell, the majority of the blue is on the front of the prism way, and on the rearmost portion of the flat area. What that told me was that the prism i cut was every so slightly too shallow, and is causing the tiniest bit of tilt to the rear. Still though, absolutely nothing worth me worrying over, the fit is miles better than the original and more than good enough for me to be happy with. If i decide to, after everything it done i can improve that contact with the bed by a lot just by sticking some sandpaper to the bed and lapping the tailstock base in, same as the carriage. I wouldnt need to take off very much at all, i think

Thats the bottom taken care of, now to flip the part and work on the top

epicfail48
01-16-2019, 07:21 AM
For the top, again, no major surprises when milling, all i needed to do was take the center bosses height down to finished size, and then rough in the 2 lower bearing surfaces. Now, i left the part very much thicker than the final finished size was due to be, and given the cutting capabilities of my mini-mill, this took a while to do. a 4-flute HSS 1/2" roughing end mill made amazingly short work of it though, at least for this class of machine. Something about the serrations breaks up the harmonics and i can really push a good cut, i was taking .150" DOC passes with around 70% cutter engagement, small potatoes for people with the big old iso-40 taper machines but pretty bloody good for me. Still took some time though.

https://i.imgur.com/PDd0LJv.jpg
Touching off the top of the part to start making some chips. If you look at the side, you can see the layout marks i put in earlier. Forgot to write-up the layout work, but i added that as more of an anti-bozo measure. Im working off the DRO, but its still handy for me to have the lines there just to reinforce things. As you can see by the lines though, ive got a lot of material to take off.

https://i.imgur.com/ZWK3h6j.jpg
The part, roughed in. I removed the bulk of the material with the 1/2" roughing end mill, leaving about 20 thou on the bottom to clean up with a carbide 1/2" regular end mill, shooting for 10 thou worth of material to take off at the surface grinder. The central boss that the tailstock uses to alight itself to the base was roughed in at the sides with the roughing end mill, brought closer with the 1/2" finisher, then went back with a 1/8" end mill to both cut in some grinding relief grooves and bring the center to final width.

The last picture skips over me cutting the adjustment slot in the base, but again, no surprises there. Simple slot cutting operation, made complicated by me forgetting my fractions and accidentally making the slot 5/16" instead of 1/4" like i had on my prints. Stupid mistake to make too, my idea was to run down the center of the slot with a 3/16" end mill, then step over to both sides to make a 1/4" slot with clean sides. Almost worked, except i was working off having a .032" step to each side, when i shouldve stepped over .016 to each side. Stupid mistake to make, but thats what happens when youre me. Course, i also forgot that that slot has a counterbore milled on the other side for the nut to slip into, didnt even remember to put that in my plans. Got it taken care of though.

epicfail48
01-16-2019, 07:28 AM
And thats the rough machining finished up. Heres the new base, next to the original one:
https://i.imgur.com/crQAllS.jpg

Mines on the right, if you couldnt tell. All the important features are cut, with the top bearing surfaces standing about .011" higher than the proper number to get the tailstock on the lathe centerline. Thats an intentional number, the next step is going to be tossing this on the surface grinder. Not strictly needed, but my grinder is a lot more guaranteed to get those surfaces parallel to the base and at the right height, both of which will be needed to get the tailstock lined up how i want it to. Not anything that couldnt be milled, i just trust my grinder more.

View from the side:
https://i.imgur.com/rgPvucs.jpg

The angle on the front has no purpose, i just think it looks good.


And the bottom half:
https://i.imgur.com/SMcS6gx.jpg

You can see the counterbored slot i was talking about here, nearly forgot to add that in. Ended up getting it, but i forgot just how much my mill hates plunge milling, that was a noisy slot to make.

Again, thats all the rough machining taken care of. Lot of work, but time well spent in my opinion. Next up is surface grinding the tops and truing up the bearing surface on the tailstock proper, not much work left at all.

epicfail48
01-16-2019, 07:48 AM
Bit out of order, but as mentioned i broke out the layout fluid and scribes to give myself some lines to, well, keep me in line during the machining. Ill be using the DRO on the mill for the actual work, but this will help prevent any bouts of stupidity. Before starting any of this, i did draw up the part in Fusion 360 just to get all the dimensions squared away, you can find that drawing here if youre interested: https://a360.co/2TTkIlo

A few important things to note; the original part seems to have been measured in metric, however being that im in the US, i work in imperial. That in mind, any critical dimensions on the part are done in their original metric measurements as close as i can get, while everything else is in imperial. That accounts for some of the wonky dimension. The second important thing is that while the original part was 2.5" wide, thanks to material constraints in what i have my base will only measure 2.2" wide. The loss in width im not concerned about at all, but the drawing does have the part modeled at that 2.5" width. That brings me to the last important point; the datum reference on this part is the center hole, not any of the edges or corners. The reason i did it this way is that no matter how wide the part is, the distance from the center hole to the edges of the center boss and distance to the adjustment slot have to remain the same. If the datum reference was one of the sides, if the width of the part changes from the plans, it could throw off one of the other measures. Anyway, onto the layout

https://i.imgur.com/6po4sH9.jpg
Bottom of the base. This side has been ground on the surface grinder, and will serve as the fact that the other measurements are references off.

https://i.imgur.com/gtK5uli.jpg
Top of the base. Note the center-punched holes for the ends of the slot and the center hole, none of those are going to be used. They were all entirely for the sake of reference, actual positioning will be handled by the DRO.

https://i.imgur.com/R3tLO8F.jpg
Front view. You can see how much ill be taking off, i cut the piece pretty thick, but in my defence id rather have too much than not enough and the piece was very rough to start with

https://i.imgur.com/H5iziYe.jpg
And the side view, which is the most complex of the 4. Nothing particularly hard to lay out though, just the prism way, a relief channel down the center of the bottom, and the angle on the front to make it look all sleek. You can also see a line almost at the center of the height, thats the height line for the bearing surfaces on the top. I ran that line all the way around the part, just to make sure i could see it no matter how the part was in the vise

danlb
01-16-2019, 03:46 PM
Nicely done. Now I'm wondering when I last checked my tailstocks. It's been a while. :)

epicfail48
01-17-2019, 05:15 AM
Another day, another few steps knocked out. Got the base almost all finished up, did the surface grinding earlier today. Not as many pictures, my hands were far too dirty for that, bug i can still go through the process.

Jumping into is, as i mentioned before i left the bearing surfaces on the tailstock base about .010" higher than needed, so i could take off the remainder on the surface grinder for best results. First things first, i need to measure exactly how much i needed to take off. I also needed to take off a bit of material from the actual tailstock to get the bearing surfaces on it parallel to the quill travel. Ended up doing that on the mill in the vice and face-milling the pads, no pictures of that but all it was was a lof of tapping to get the quill dead parallel to the table, then a quick pass over. After that, the base part was brought over to the surface grinder and the base pieces were just barely cleaned up:
https://i.imgur.com/KAqDRmj.jpg
https://i.imgur.com/6JDRBjH.jpg

At this point, the tailstock was reassembled and mounted on the lathe, and the center height was measured same as it was initially. Same as before, subtracting the tailstock center height from that of the headstock gave me the exact measurement of how much i needed to take off. In this case, i needed to take off another .002", so back to the grinder. Heres everything all together:
https://i.imgur.com/4nDn8Zo.jpg

With the grinding finished up, it was time to reassemble everything and check the rough alignment, specifically the center height, tilt and yaw. Here again, hands were too filthy to touch the camera, but the process went well enough. The tailstock center ended up about .002" below the headstock, if my height gauge gave an accurate reading, though im hoping that i just messed up the math somewhere. Not the end of the world if it is actually .002" low, i can pretty easily shim that up, i was just trying to go for <.001" tolerances on this one. Tilt came out solid, the bearing points on the base are dead parallel to the bed, and the tailstock propers contact to the base is right in line with the quill. Think i measured something like 3 tenths of misalignment there.

Yaw was another story, measuring it i was about .005" off across the length of the quill. Did some inspection, and it turns out the Y axis on my mill is off square to the X axis, by about .1 degree. Since i used the Y-X axes of travel to cut the boss of the base relative to the prism ways, that inaccuracy was recreated on the part, leading to the misalignment. Realignment meant getting creative and recutting the reference side of the boss. Luckily, while the Y axis of my mill is off, the Z axis is as square to the table as i can measure. To fix the alignment, i dialed in the prism way to be perfectly vertical, then face milled the left side of the base, then clamped the base with that fresh cut face against the vise's fixed jaw. Since the left side of the piece was now square to the prism way, as long as the reference side of the boss was parallel to the side of the part, the boss would be square to the prism way and the tailstock quill travel would be in-line with the bed of the lathe. Luckily, thats exactly how it ended up working out.

All thats left now is to get the new base piece painted and then get everything reassembled and aligned. Rather, now im just waiting for the paint to cure, since i already did that. More on that later though

epicfail48
01-17-2019, 05:20 AM
Forgot to mention, youll notice that in the picture of the assembled tailstock, the base is a little narrower than the tailstock proper. I already touched on it, but the piece i used for the base was narrower than the original base by about 1/4" and thats why it looks narrower; because it is narrower. Technically bad practice, but honestly i dont foresee and issues. Yes, a narrower contact area makes for a weaker connection, but the contact on the new piece is far and away better than the old one, and the tailstock on this lathe i doubt will ever see any forces that will make that missing 1/8" on either side necessary. Just looks a little weird

epicfail48
01-18-2019, 02:49 AM
Finally got things finished up. First off, some painting. Trip through the ultrasonic cleaner, then degreasing, then i got all the precision surfaces taped off, im not too keen on the idea of having mating surfaces covered in springy paint...
https://i.imgur.com/D3o0kZi.jpg

Ive noticed that not a lot of manufacturers seem to share that sentiment, but hey, fit and finish is important. Following the taping i hit the base with a coat of self-etching primer, then a heavy coat of some oil-based enamel. Couldve sworn i had a can of some Grizzly green around i was going to use, but couldnt find it. Had to settle for mid-60's Delta grey instead. Good thing i dont care how this thing looks. Got everything reassembled:
https://i.imgur.com/fsvJUGR.jpg

Yeah, you can really tell that the base isnt original... in my defense the paints just to protect the metal. Anyways, following getting everything painted and reassembled, time to work on getting everything aligned. Im going to be following the exact same steps as i did at the start of this to verify where work was needed, only this time i wont be taking any photographs. Disappointing, i know, but my hands were too grimy to touch my fancy new camera and i was messing about with tools every 2 seconds anyways. This also means youll have to take my word on the numbers, as i cant back them up with evidence.

First up to check was pitch and yaw, for you aircraft fanatics. Before i started all this, i believe i measured the side of the quill closest to the headstock as being low by about .002". With the new base and after truing up the tailstocks bearing points to be parallel with the quill, i cant even measure a difference. Admittedly, not using a tenths indicator or anything, but still, less than i can measure with my 15-0-15 DTi is still plenty accurate enough for me. Yaw im particularly happy with, here again i measured about .002" originally, and as a matter of fact after machining the base the first time i measured a .005" difference front to back. After the second trip to the mill to fix that surface up, cant even measure the yaw being out of parallelism with the bed ways.

So, with the rotational axis take care of, all that was left to do was get everything brought in like front-to-back and up-to-down. Front to back was easy to do, thanks to that 2 piece tailstock and the adjustment mechanism i added when i got the lathe, got that dialed in to about 5 tenths out. Up and down was the reason i started this entire endeavor, the tailstock centerline was about .005" above the headstock centerline. With the new baseplate, i was shooting for dead-nuts on centerline, and ended up at... .002" below centerline. Not gonna lie, im a little disappointed here. Still getting used to the surface grinder, and i know thats where i messed up a measurement somewhere. Not too big of an issue of course, with it being below centerline a fix is as easy as shimming between the tailstock and the baseplate and thats exactly what i did, but still, i was aiming at a tolerance of half a thou. Still got some learning to do there. Anyways, alignment ended up being dialed in to half a thou to the headstock centerline.

Now, the big question; was it worth it? Well, the numbers say ive got the tailstock and headstock pretty dead in-line, but some real-world tests are needed. Quickest and easiest way that i know of is to chuck up a spotting drill in the tailstock and make a spot. Used to be useless for me, because the spotting drill being off-center would leave an inverted cone at the bottom of the spot which would knock the following drill off center. Now, well:
https://i.imgur.com/RhePkWy.jpg

I clearly need a better spotting drill, this one i think is a bit dull and chattered a bit. Still though, the center is nice and point, if somewhat triangular, and that seemed to indicate that the tailstock was pretty bang-on center. Following this up, i chucked up a #47 drill, something nice and small that would show with a wobble if i was off center, which it really did before. Now, rock solid, and getting the nice, long chips indicative of a clean drilled hole. Before i would always get more almost powdery chips caused by the tailstock being off-center, as well as the direction of the feed angle being somewhat off angle. Here again, a very definite improvement. The final thing i wanted to test, center-drilling a piece of stock, then supporting it with a live center and taking a cut. Before, the center would actually push my workpiece off parallel with the bed was, caused me to cut a taper. Now though:
https://i.imgur.com/ALlFuyj.jpg

Nothing special, just some scrap 304 stainless and a HSS tool bit, bout a .010" d.o.c, .002" feed rate, and thats about a 2" length of cut. No exact before numbers, but i can say that between centers like this, i used to see anywhere between .002-.010" taper, between the tailstock forcing the work to deflect with its misalignment and just random deflection. This time, i measured the chuck end at .4308" and the tailstock end at .4312". Now, 4 tenths may not be anythign to write home about for some of you guys, but for my idiot self on my little toy lathe, thats a pretty nice number to have. Another thing to note, this is the best surface finish ive ever got off a cut, hands down. Everything ive done recently, the new bearings, the carriage gibs, getting the tailstock inline, its all combined to cut down a lot on deflection and chatter, and while i was getting decent before with the lathe in its factory state, this is pretty bloody good.

So, i can safely say that thus far its been effort well spent. Makes me feel pretty good moving forward with everything else!

epicfail48
01-18-2019, 03:07 AM
Last test cut, this time with carbide inserts:
https://i.imgur.com/R4xx216.jpg

And to think, these are the el-cheapo ebay special inserts that i used to not be able to use because of tool deflection. Need to get a DCMT tool holder now, my CCMT tools wont clear my centers without rotating the tool post. Nice knowing i can use the regular steel inserts now, without having to find the polished aluminium ones

mattthemuppet
01-18-2019, 12:16 PM
fabulous work, especially with the tail stock base. I would still look into getting some CCGT or DCGT inserts, they make all the difference on these small light lathes. I can cut steel with a CCMT insert on my Atlas 618, in fact I often do most of the "roughing" with a CCMT, but the finish sucks. Using a CCGT insert for the last 0.01" or so makes all the difference - lovely finish, whatever the material, and easy to get on size without any tool or work deflection. I really can't recommend them enough!

epicfail48
01-18-2019, 02:59 PM
fabulous work, especially with the tail stock base. I would still look into getting some CCGT or DCGT inserts, they make all the difference on these small light lathes. I can cut steel with a CCMT insert on my Atlas 618, in fact I often do most of the "roughing" with a CCMT, but the finish sucks. Using a CCGT insert for the last 0.01" or so makes all the difference - lovely finish, whatever the material, and easy to get on size without any tool or work deflection. I really can't recommend them enough!

I've actually got some CCGT inserts, and I love them as much as you do. Problem I've found with them is that thanks to the high rake angle, they're pretty delicate, and I've snapped a few tip. The CCMT inserts seem a bit more robust, and I wanted to get them working for at least roughing, especially given that I'm planning on doing some turning work on some 4140ph to make some endmill holders. CCMT are cheaper too, both of which trends I'm hoping hold true with the DCMT vs DCGT

RB211
01-18-2019, 04:47 PM
I've actually got some CCGT inserts, and I love them as much as you do. Problem I've found with them is that thanks to the high rake angle, they're pretty delicate, and I've snapped a few tip. The CCMT inserts seem a bit more robust, and I wanted to get them working for at least roughing, especially given that I'm planning on doing some turning work on some 4140ph to make some endmill holders. CCMT are cheaper too, both of which trends I'm hoping hold true with the DCMT vs DCGT

I think rigidity plays a huge role to maintaining the life of cutting edges, and being able to maintain proper speeds and feeds. I wonder if you could make the mini-lathe more rigid by filling the gaps in the lathe bed with concrete?

mattthemuppet
01-18-2019, 05:04 PM
I've actually got some CCGT inserts, and I love them as much as you do. Problem I've found with them is that thanks to the high rake angle, they're pretty delicate, and I've snapped a few tip. The CCMT inserts seem a bit more robust, and I wanted to get them working for at least roughing, especially given that I'm planning on doing some turning work on some 4140ph to make some endmill holders. CCMT are cheaper too, both of which trends I'm hoping hold true with the DCMT vs DCGT

it'll be interesting to see how they fare now that you've tightened everything up considerably. I've gone through a fair few tips, though in my hands it's usually because the belt slips and the tip jams into the work. As soon as I've made a polyV spindle pulley I imagine that I'll have fewer breakages. Still, having both CCMT and CCGT inserts set up let's you get the best of both worlds :)

epicfail48
01-18-2019, 06:37 PM
I think rigidity plays a huge role to maintaining the life of cutting edges, and being able to maintain proper speeds and feeds. I wonder if you could make the mini-lathe more rigid by filling the gaps in the lathe bed with concrete?

Yeah, rigidity plays a huge part. Im fairly certain the reason i was losing tips before was that the play in the carriage was just enough to let the tool rotate, and it did not seem like the inserts appreciated that. I also know that chatter plays merry hell on carbide, and lack of rigidity is a huge contributor to that as well. Seems like fitting the carriage gibs better did a lot to improve rigidity at the cutter, and im 90% certain that my reworking the tailstock was a massive increase in the rigidity of that as well. Small improvements, of course, but when you stack them up, well, results are obvious.


it'll be interesting to see how they fare now that you've tightened everything up considerably. I've gone through a fair few tips, though in my hands it's usually because the belt slips and the tip jams into the work. As soon as I've made a polyV spindle pulley I imagine that I'll have fewer breakages. Still, having both CCMT and CCGT inserts set up let's you get the best of both worlds :)

Seeing how the mt's worked, ive got no doubt tht the gt's will absolutely sing through the work. The gt's actually did a good job on pieces before i even replaced the headstock, the only issue i had was longevity. Im thinking that the longevity issue is a non-issue now, so i cant wait to do some testing. Heck, cant wait to see how hard i can push some of my HSS tooling now, ive got a rougher ground that i used before all this, could take a max cut of about .020" in stainless before it started to chatter. Trying it last night i was taking a .040" DOC, and i probably couldve pushed it harder.

danlb
01-18-2019, 11:43 PM
Thanks for doing this thread. Because if your work I realized that I had not checked the tailstock on my 9x20 in years. I'm happy to say that it's at the correct height and a dead center in the tailstock touches tips with the one in the spindle regardless of how far it's extended. This should indicate that the barrel is parallel to the ways too. I'm a bit too tired to do the two collar test. I'll give that a shot tomorrow if the flu lets up some.

Dan

epicfail48
02-14-2019, 05:26 AM
Quick update on the tailstock, so far the new base is working fine, but i noticed when turning a few pens recently, using a live center, i was getting a bit of taper over the length of the pen. Went through the usual suspects, checked headstock alignment, made sure the tailstock was in line, etc. Finally got it to where i could turn a test piece between centers with the diameter being consistent to .0003" (If memory serves. Didnt write it down) on either end of a 5 inch test piece. Then i cut the piece in half and turned the half between centers. Got something like .0025" over the 2ish" length.

Explains why it always feels like im chasing my tail when trying to align the tailstock. All that time moving the tailstock proper back and forth on the base plate, i never considered that the lathe bed would be at fault, seems like theres a bit of twist to it. Makes sense though, in how i can have the bloody thing perfectly aligned 8 inches from the chuck, then turn a taper on a 3 inch workpiece supported with the center. Twist forced the center toward the operator, workpiece is narrower at the tailstock end.

So, clearly this issue takes precedence, im not too fond of my workpieces being cones. Looking more for cylinders. At present the lathe is sitting on its plastic feet on a wood workbench, great for portability but clearly not for accuracy. The leading idea for a fix thus far is to make a new bench and bolt the lathe to that, before investing in a machinist level and levelling the bed. The frontrunner for the new bench material is to pour a concrete slab thats the same size as the present bench top, 2'x3'x2", and just reuse the current base. The concrete im thinking would add a fair bit of mass and rigidity, without being too cost-prohibitive, and the current base, while being just framing lumber, is pretty well over-built and should hold the weight pretty well. Much as id love to just used a nice, beefy slab of 1/2" steel, no way can i afford that. Figure the concrete should give me a pretty beefy something to bolt the lathe too.

Any other ideas are appreciated though!

epicfail48
02-14-2019, 06:18 AM
Addendum to the plans for a new lathe stand, steel may still be in the running. It occurs to me that a 1/2" slab of steel is massive overkill, considering that i used 1/4" for the top of my surface grinder stand. Problem is, that stand was only 18"x24", versus the 36"x24" planned top for the lathe bench. Given the choice between 1/4" steel and 2" concrete, which would seem like the better option? Im leaning more to the steel at the moment, provided the price isnt insane. If 1/4" is stiff enough to reasonbly be expected to support the lathe without sagging, the 60lbs is a lot more appealing than concretes 160lb estimate

Baz
02-14-2019, 07:36 AM
2x3 is a standard paving slab size if you can find an old one not the new thin as we can possibly make them ones. Also you don't need it to cover the whole bench so a 1ft wide gravel board would also do, especially for an extra long lathe.
Although my Boxford is on a 3/8in steel plate it's stability is due to the angle iron frame and concrete floor below that. Steel itself is quite bendy and affected by temperature so not in itself an ideal base. Cast iron is more rigid but still relies on a decent floor.

greystone
02-14-2019, 09:37 AM
1/4" steel is like spaghetti over a 36" span.
So is 1/2", btw, unless it has a rigid stable substrate.

A bridgeport cast iron table is about 4", and is very flexible, and will bend 0.04 mm or more with 2 fingers diagonal pressure.

Idea.
Weld or bolt studs to the 1/4" steel, cast concrete 3-4" thick on it, after 2 weeks very gently surface grind the top (to not heat the steel).

My 7x lathe stand, made around 2015, is 125 mm thick concrete, topped by 2x12 mm mild steel flats, total 24 mm thick.
150 kg.
9/10 in functionality, excellent vibration control, much more stiffness. Much less noise.



Addendum to the plans for a new lathe stand, steel may still be in the running.
It occurs to me that a 1/2" slab of steel is massive overkill, considering that i used 1/4" for the top of my surface grinder stand. Problem is, that stand was only 18"x24", versus the 36"x24" planned top for the lathe bench. Given the choice between 1/4" steel and 2" concrete, which would seem like the better option? Im leaning more to the steel at the moment, provided the price isnt insane.

If 1/4" is stiff enough to reasonbly be expected to support the lathe without sagging, the 60lbs is a lot more appealing than concretes 160lb estimate

RB211
02-14-2019, 11:04 AM
Mount the lathe to a heavy piece of C channel, after that, you could use a plastic table for a stand if you wanted. All of my small lathes are mounted to C channel.

cameron
02-14-2019, 12:27 PM
Mount the lathe to a heavy piece of C channel, after that, you could use a plastic table for a stand if you wanted. All of my small lathes are mounted to C channel.

Any open section, channel, angle, I- or W-beam, has low torsional rigidity relative to its size and weight.

Boxing the channel with a plate across the flanges, even with something as light as 1/8" steel, will add a big increase in resistance to twisting.

epicfail48
02-14-2019, 03:12 PM
Seems like the general consensus is that, from a stability and rigidity standpoint, a concrete slab top would be the better option. Was afraid of that, I'm more used to metal than I am stone, and concrete is bloody heavy... Much as I'd like to keep the top size the same, may end up shrinking it down a bit just to shave some weight off.

This does bring up some dimension questions though. Much as I'd love to just pour a 2'x3' slab 5" thick and be done with it, I'm a one-man shop with no heavy lifting equipment. Mass may be better, but if I can't move it it's useless to me. So, question is, how thick should I be looking? Assuming I shrunk the top to better fit the dimensions of the mini lathe, something like 18"x24", could I get away with something like 2" thick? I know, thicker is better because it imparts more mass and stability, but at the same time I don't need something I can park a tank on, just something stiff enough to allow me to torque the bed a bit. Lighter is a bit better for my situation anyways, and a slab that dimension should clock in at about 60lbs. Lot easier to manage moving that

ulav8r
02-14-2019, 09:02 PM
To keep weight down, make the concrete about 6 wide by 8 deep by 24 inches, then wood aroud that to increase the area as desired. That would weigh about 1/4 of the 2'x3'x5".

Mcgyver
02-14-2019, 10:29 PM
Concrete adds mass but it moves about for years - if it moves so will the shape of the lathe bed. A quick solution might be a cheap surface plate, drill and epoxy in mounting studs. If you really want a great solution, make a mini box girder, normalize and fill it with epoxy granite. Rigidity, stability and vibration damping. Either scrape the mounting points into the same plane, or attach the lathe to it then check the bed and scrape as necessarily. You may not want to do that much, but its the full throttle solution.....same way you found that cross slide ground but not flat....there's a good chance you'll find the ways the same way, especially after you bolt it to something....but you're learning how almost anything can be made perfect with patience and scraping

shampine1
02-14-2019, 10:31 PM
Rectangular tubing would give you what you want.
Concrete has the major disadvantage of a different coefficient of thermal expansion than cast iron. Steel is much closer.
One of my mentors at Rice used I beam under his Atlas. Sneaky trick is to float the lathe on epoxy. Set it up on the I beam, level things, fiddle to taste, and then put epoxy between the two. After it's set, drill out the mounting holes, and bolt.

Sent from my SAMSUNG-SM-G891A using Tapatalk

shampine1
02-14-2019, 10:33 PM
If you want lots of damping, I can point you at some precision machine techniques. Basic idea is nested tubes. You wrap the inner one with rubber, slip them together, and inject epoxy between them.

Sent from my SAMSUNG-SM-G891A using Tapatalk

Mcgyver
02-14-2019, 10:34 PM
Sneaky trick is to float the lathe on epoxy. Set it up on the I beam, level things, fiddle to taste, and then put epoxy between the two. After it's set, drill out the mounting holes, and bolt.

I like that

1200rpm
02-14-2019, 11:16 PM
call around to used machinery dealers and ask if they have any cast iron surface plates...they scrap them all the time.

J Tiers
02-15-2019, 01:28 AM
Addendum to the plans for a new lathe stand, steel may still be in the running. It occurs to me that a 1/2" slab of steel is massive overkill, considering that i used 1/4" for the top of my surface grinder stand. Problem is, that stand was only 18"x24", versus the 36"x24" planned top for the lathe bench. Given the choice between 1/4" steel and 2" concrete, which would seem like the better option? Im leaning more to the steel at the moment, provided the price isnt insane. If 1/4" is stiff enough to reasonbly be expected to support the lathe without sagging, the 60lbs is a lot more appealing than concretes 160lb estimate

So.... what is the goal here?

Do you want to make the machine more rigid, or do you want a massive base? Or do you want both?

The 1/4" may be "like spaghetti" if you want to call it that, but actually that does not matter much in some ways. Let's assume you want to make the machine more rigid. Sooooo.... what does "more rigid" mean?

1) It means, for instance, that if you push down in the middle of the bed, the machine flexes less. (Ditto for pulling up, presumably, bit that is less of an issue). OK, what HAPPENS when you push down? The middle bends down, and the ends where the feet are, will tilt, moving the holes in the feet outward.
Thin material will not do much for the tilt, but it surely CAN help with the moving of the holes outward. They can't tilt much without moving outward. So bottom line here is that yes, a piece of 1/4" steel will help this mode of flexing. So yes, more rigid this way.

2) It also means that if you twist one end of the machine vs the other, the machine twists less. OK, then, what happens when you twist the bed? Well, the "foot" at one end tilts sideways relative to the other one, and it's pair of mounting holes moves sideways relative to the other ones. Again, the thinner metal will not resist the tilt, but it DOES resist distortion in the plane of the sheet (shear).
So bottom line with that flexing mode is that yes it WILL HELP resist that.

3) It further means that if you push sideways on the bed, it flexes less. In this case, the feet may stay in the same plane, but the bed bows sideways, and the holes in the feet move relative to each other so the rectangular pattern becomes slightly trapezoidal. The metal resists this, as it resists distortion in the plane oof the sheet, as in '1" and "2" above. So here, too the plate is good.

All situations would be even better if the sheet of metal is on top of a wood bench. That will take the responsibility for support away from the metal, and make it just responsible for keeping the feet from moving sround in the plane of the metal. That will partly "box-in" the bed, and increases rigidity. The wood table will also damp any vibrational modes that the metal might have. You probably want the bolts to fit the holes in feet and plate pretty tightly, and/or have them torqued pretty tight to prevent sliding around relative to each other of the bed and plate. You will need to shim or otherwise align the bed so when bolts are tightened it is in alignment.

Would a concrete base be even better? Or a piece of 1" plate? Sure.

It would, if thicker, clearly resist the tilting of the feet, at least if grouted-in with epoxy or regular grouting mix. It will still resist the movement of the feet which would tend to shear it in the plane of the top, the same way the 1/4" steel does. And it will add mass.

Even with all that, you have to limit your expectation a bit, because the strongest and most rigid base cannot do anything but hold the bottom of the feet in position. ANY other flexing that the thin and flexible bed can do, or that the relatively thin "foot" structure does, cannot be resisted by the base. The solid base can only make the most of whatever structure is attached to it.

It would be good to mount the feet to plates of metal set in the concrete, to give a definite surface to shim against.

epicfail48
02-15-2019, 05:24 AM
Concrete adds mass but it moves about for years - if it moves so will the shape of the lathe bed. A quick solution might be a cheap surface plate, drill and epoxy in mounting studs. If you really want a great solution, make a mini box girder, normalize and fill it with epoxy granite. Rigidity, stability and vibration damping. Either scrape the mounting points into the same plane, or attach the lathe to it then check the bed and scrape as necessarily. You may not want to do that much, but its the full throttle solution.....same way you found that cross slide ground but not flat....there's a good chance you'll find the ways the same way, especially after you bolt it to something....but you're learning how almost anything can be made perfect with patience and scraping

Funnily enough, i thought about the surface plate idea. Problem is, a surface plate large enough to fit the lathe costs more than i can justify spending. Be a little easier if there were more of used market for machine tools in my area, but the market is pretty dead around these parts.


So.... what is the goal here?

Do you want to make the machine more rigid, or do you want a massive base? Or do you want both?

The 1/4" may be "like spaghetti" if you want to call it that, but actually that does not matter much in some ways. Let's assume you want to make the machine more rigid. Sooooo.... what does "more rigid" mean?

1) It means, for instance, that if you push down in the middle of the bed, the machine flexes less. (Ditto for pulling up, presumably, bit that is less of an issue). OK, what HAPPENS when you push down? The middle bends down, and the ends where the feet are, will tilt, moving the holes in the feet outward.
Thin material will not do much for the tilt, but it surely CAN help with the moving of the holes outward. They can't tilt much without moving outward. So bottom line here is that yes, a piece of 1/4" steel will help this mode of flexing. So yes, more rigid this way.

2) It also means that if you twist one end of the machine vs the other, the machine twists less. OK, then, what happens when you twist the bed? Well, the "foot" at one end tilts sideways relative to the other one, and it's pair of mounting holes moves sideways relative to the other ones. Again, the thinner metal will not resist the tilt, but it DOES resist distortion in the plane of the sheet (shear).
So bottom line with that flexing mode is that yes it WILL HELP resist that.

3) It further means that if you push sideways on the bed, it flexes less. In this case, the feet may stay in the same plane, but the bed bows sideways, and the holes in the feet move relative to each other so the rectangular pattern becomes slightly trapezoidal. The metal resists this, as it resists distortion in the plane oof the sheet, as in '1" and "2" above. So here, too the plate is good.

All situations would be even better if the sheet of metal is on top of a wood bench. That will take the responsibility for support away from the metal, and make it just responsible for keeping the feet from moving sround in the plane of the metal. That will partly "box-in" the bed, and increases rigidity. The wood table will also damp any vibrational modes that the metal might have. You probably want the bolts to fit the holes in feet and plate pretty tightly, and/or have them torqued pretty tight to prevent sliding around relative to each other of the bed and plate. You will need to shim or otherwise align the bed so when bolts are tightened it is in alignment.

Would a concrete base be even better? Or a piece of 1" plate? Sure.

It would, if thicker, clearly resist the tilting of the feet, at least if grouted-in with epoxy or regular grouting mix. It will still resist the movement of the feet which would tend to shear it in the plane of the top, the same way the 1/4" steel does. And it will add mass.

Even with all that, you have to limit your expectation a bit, because the strongest and most rigid base cannot do anything but hold the bottom of the feet in position. ANY other flexing that the thin and flexible bed can do, or that the relatively thin "foot" structure does, cannot be resisted by the base. The solid base can only make the most of whatever structure is attached to it.

It would be good to mount the feet to plates of metal set in the concrete, to give a definite surface to shim against.

Clarifying my needs for this, i want something i can bolt the lathe bed to thats stiff enough to un-twist the bed from its presently twisted condition. I dont expect this to make the lathe any more rigid per se, just need to deal with the twist. Any benefits other benefits are secondary, i.e extra mass to dampen vibrations and the like.


Rectangular tubing would give you what you want.
Concrete has the major disadvantage of a different coefficient of thermal expansion than cast iron. Steel is much closer.
One of my mentors at Rice used I beam under his Atlas. Sneaky trick is to float the lathe on epoxy. Set it up on the I beam, level things, fiddle to taste, and then put epoxy between the two. After it's set, drill out the mounting holes, and bolt.

Sent from my SAMSUNG-SM-G891A using Tapatalk

Interesting point, and i actually looked into that. According to the numbers i found, concrete averages at about 10 millionths of a meter of expansion per degree Celcius, compared to cast irons 10.8 and steels 11. Honestly, for my uses i figure those are all identical enough, its not that i dont thing that whatever i mount the lathe to can force the lathe to warp, more that the amount that the base forces the tool to warp is going to be less than the flex the lathe sees in normal operation. I have no illusions here, i doubt the lathe ill notice if its bolted to steel or concrete give than i can probably flex the base by several thousandths by pressing on it.

epicfail48
02-15-2019, 05:46 AM
After dwelling on it for a bit, i realized ive been overthinking things on this. My train of thought has been stuck on bolting the lathe to a big, sturdy table or worksurface, essentially turning a portable tool into a facsimile of a big old stationary machine. Seems to me like that line of thought its probably gross overkill, especially given the spirit of my working on this lathe; make it work as best as it can, but dont waste a lot of effort actually trying to turn a sows ear into a silk purse.

To that end, i realized that i dont need to bolt the lathe to a big, heavy work surface, i just need to bolt the lathe to something stiff enough to counteract the twist of the lathe bed. Following that train of thought, the frontrunning idea right now it to roll with the concrete idea, but make a slab 9"x27", just big enough to fit the lathe itself, and 3" thick. A slab that size should be stiff enough to bolt the lathe to, without making it a permanent installation, and i wouldnt even need to make a new workbench, i could just plop the slab down on the existing bench.

Hopefully i havent missed anything huge here. The bed on this lathe shouldnt require overly much force to take out the twist, and im thinking that a 3" thick slab of concrete should be more than stiff enough for that. Strikes me as being the same train of thought as using a surface plate, only concrete instead of granite. Now, i know concrete isnt as stable or stiff as granite, but im thinking that it should work well enough for my application. Unless im missing something big, i may get to work on that soon, as mentioned after mulling everything over for a few days this seems like the best fit for my needs

J Tiers
02-15-2019, 09:06 AM
I think that is practical and realistic.

You will get an improvement in rigidity, but only the concrete type solution will give a rigid base the force the thing into a twist against its natural warp, if that is what you want.

nickel-city-fab
02-15-2019, 12:12 PM
I have a mini lathe like yours. Best base I could find for the least money, was a scrap chunk of ten- inch wide flange beam about three feet long. Got it for free. Tool the rubber feet off and bolted solid to one flange of the beam.

RB211
02-15-2019, 02:30 PM
That sheet metal stand is made from 3/16" sheet metal, and has a combined weight of 250 lbs. The lathe is over 850 lbs, and it twists like spaghetti. The stand has 6 leveling pads on the floor. Taking an 8" precision Starret level, the lathe was made level along the entire bed for twist, and made level in X and Y. The point of this is that very fine adjustments were made to all six leveling pads, and adjusting just one threw off the others. Even a huge chunk of cast iron will flex easily, and that sheet metal stand was made to tame it and hold it level. You do not need or want concrete for that. The C channel, either open or welded with a plate across the flanges, will stabilize the twisting, but you still will need to adjust the flex. Either use shims like feeler gauges, or another method. It is ridiculous to play with concrete for a table top.https://uploads.tapatalk-cdn.com/20190215/4d33e4fea8ffc62e1918b8542e800ef4.jpg

Danl
02-17-2019, 12:00 AM
Very impressive work on this lathe.

I agree with RB211 on the need to be able to adjust against flex. Have you given any thought to checking with a local headstone maker? Most of them have reject piles lying out back somewhere, and the size you are looking at could easily be found there for free or very cheap. If you have a strong back or can get some help getting it home, you could locate some epoxied-in expansion anchors matching your lathe mounting holes and using shims and/or double nuts on the anchors, have plenty of adjustment.

I know, headstones are not 'flat'. But you would not be using it for a surface plate, and it would give you a lot of rigidity.

Just a suggestion.... again, nice work on this, work that you can be proud of and should last as long as the lathe lasts.

Dan L

1200rpm
02-17-2019, 02:13 AM
I think I would just go to the local cabinet maker and get a chunk of granite....1-1/4" is a standard thickness...plenty for a lathe of that size.

J Tiers
02-17-2019, 02:57 AM
Ummmmmm... RB.....

You might want to compare the massive bed on your picture with the scrawny little bed on most mini-lathes. They can use more rigidity, and a heavy base can provide it.

Your 3/16" material will also make an improvement, refer to comments about twist above. But it will not be as good as a concrete or heavy steel base.

RB211
02-17-2019, 03:22 AM
Ummmmmm... RB.....

You might want to compare the massive bed on your picture with the scrawny little bed on most mini-lathes. They can use more rigidity, and a heavy base can provide it.

Your 3/16" material will also make an improvement, refer to comments about twist above. But it will not be as good as a concrete or heavy steel base.

One must balance the needs of practicality/convenience and what is best. I agree with you.