Lathe setup question(s)

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tornitore45
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Re: Lathe setup question(s)

Post by tornitore45 »

Before investing in a machinist level that you may use twice in a lifetime. Try running your late and see what results you get.
My lathe was never leveled and is turning out part with no taper or a taper I can not detect.
There are lots better ways to spend $200 in tooling.
This approach of mine is sure to raise the eyebrows om many, but is eminently practical.
Besides if a late is not very accurate to start with, because of wear or genetic, there only so much fiddling and adjusting can do.
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John Hasler
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Re: Lathe setup question(s)

Post by John Hasler »

A lathe bed has to be flat. Leveling is the usual way to achieve that but not the only one.
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tornitore45
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Re: Lathe setup question(s)

Post by tornitore45 »

A lathe bed has to be flat. Leveling is the usual way to achieve that but not the only one.
OK John do not keep us in suspense.
Mauro Gaetano
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John Hasler
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Re: Lathe setup question(s)

Post by John Hasler »

tornitore45 wrote: Sun Sep 16, 2018 12:44 pm
A lathe bed has to be flat. Leveling is the usual way to achieve that but not the only one.
OK John do not keep us in suspense.
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pete
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Re: Lathe setup question(s)

Post by pete »

I completly agree with John, using the term "level" seems to throw some people off about what's actualy being done and what your trying to accomplish. Leveling a lathe bed is just the easiest method of getting the bed almost twist free. It could be on a 45 degree angle and if the bed is twist free it will still cut parallel.

There's also another very cheap but time consumeing method of checking a lathe bed. User name Build Something Cool on Youtube showed a video about it a few years ago. Basicaly a long vertical rod (the longer the better) clamped in any way possible to the cross slide and a standard carpenters plumb bob hung from that so it's point is a few thou clear of the cross slides top surface. You then add a dot on top of the cross slide in line with the plumb bobs point. That's your starting point. If I was using this method I'd get the headstock end across the ways to agree with where the plumb bob points by moving the cross slide across the ways until that plumb bob pointed to the exact same point at both locations. Then move to the tailstock end and do the same there. The main issue is waiting for that plumb bob to quit moving. It would certainly get you close enough to then dial in the final adjustments under cutting conditions. It may not be quite as accurate as my Mit. machinist level, but it doesn't cost $600+ either.

So where do you adjust verses the measurements you get? You need to visualize what the tool point is doing while cutting. Think of it this way, a twist in the bed will very slightly roll the tool point into or away from the shaft your test cutting. Let's say your tailstock end measures smaller than the headstock end after making a light test cut. That means the tool tip is being rolled into the work more at the tailstock side and out and away from the shaft at the headstock end. So the front side of the bedways are twisted a bit more up and very slightly roll the tool point in and towards the work at the tailstock side. I bought and still use what Emco called "leveling elements" they sold for there Compact 5 lathe. There a very simple but more than clever idea that I've not seen used by anyone on the forums or Youtube and they work extremely well. They could be made for any larger or smaller lathe. Think of a steel plate maybe twice as wide as the beds mounting foot. For my little Emco there about 1/4" thick. Bolt those plates to the lathes feet using the manufacturers holes for bolting the lathe down. Under both those plates bolt another two the same size and thickness down to your bench top if your not using a steel stand. On the top plate there's two drilled and tapped holes. One on the front and rear of each plate and outside of where the lathes mounting feet are positioned. Through those drilled and tapped holes a short fat bolt gets used. Those are your lathe bed adjusting bolts. Those bolts are through drilled there full length. Another bolt long enough to go right through the short fat bolt and threaded into either the steel stand or that bottom steel plate you screwed down to the bench top. So that bottom plate or the stand needs to be drilled and tapped for that bolts thread size. Those bolts are used to lock down the adjusting bolts after there moved and keep the lathe fastened to the stand or bench top. And also the adjustment bolts can't move over time. I changed Emco's parts count a bit and use extra lock washers under the locking bolt heads.

In use lets say the tailstocks rear bedway needed to be brought up to compensate for the above problem of the test cut piece showing the tailstocks side was small. You'd slightly adjust the rear hollow bolt down to raise or twist the rear way surface up and maybe lower the front adjuster a bit. If a test cut showed a large adjustment was needed the I'd move both. Going up on the rear bolt adjusts the tailstock end so the tool is rolled very slightly away from the test shaft. Run another test cut, measure and do further adustments to correct for any taper. Once my shop reno is done I have some 1" thick plates to replicate what Emco made for my 11" swing lathe. I'll try to post pictures here with some plate and thread sizes once those are made. Unless a lathe is large and expensive enough to have a factory method of leveling it I'd highly recommend using a system like this on any lathe that needs them. Lots seem to mention using shims to do the same. Imo there too slow, too much trial and error, not exact enough, and Emco's system is always there and completely adjustable. Having screws to do what the shims do allows any fine adjustment needed. It still requires a bit of trial and error until you get a feel for how much adjustment on the bolts will give you how much change at the tool point since getting the last few 10ths doesn't take very much. .0002" small or large on the test piece only requires .0001" change at the tool point.

If a lathes tailstock is very slightly off set so it's C/L isn't directly pointing at the headstocks C/L you'll also get a taper when using tailstock support. That's why you get the bed as level as possible first, run and adjust until you get that two collar test piece parallel, then adjust the tailstock by turning a long shaft between centers and readjust the tailstocks off set until it also turns a shaft parrallel. Once you do have that long test piece machined parallel then it can be used at any time in the future along with an indicator to reset the tailstock back to being correct if it's offset to purposly turn a taper. It can also be used by indicating the front and top of the shaft if your lathe ever needs further adjusting for bed twist. I'd still recheck to be certain by running another test cut. I think you'd spend some frustrating hrs chasing your tail while adjusting the tailstock if you don't level and get the bed adjusted dead true first.
Patio
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Re: Lathe setup question(s)

Post by Patio »

Gregg, I have a level, that you may borrow, if you would like. I can also come help look at your lathe if you would like.
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curtis cutter
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Re: Lathe setup question(s)

Post by curtis cutter »

Patio wrote: Mon Sep 17, 2018 12:11 am Gregg, I have a level, that you may borrow, if you would like. I can also come help look at your lathe if you would like.
Pat, I will take you up on that offer soon but first I have a homework/reading assignment from Pete to get done. :)
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tornitore45
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Re: Lathe setup question(s)

Post by tornitore45 »

John thanks for the link, will make for good reading.
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epanzella
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Re: Lathe setup question(s)

Post by epanzella »

First you have to check the alignment of the headstock to the bed independent of the tailstock. This can be done with a ground rod in a collet or a test bar. I use an MT5 test bar the plugs right into the spindle bore with no other attachments or parts to degrade accuracy. Best $100.oo I ever spent. Once that's done put something true like a rod or test bar on centers to true the tailstock. Once the lathe is properly set to run true, only then can you determine the condition of your chucks and whether you want to grind them.
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pete
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Re: Lathe setup question(s)

Post by pete »

A MT test bar only works if the female taper is in pristine condition with zero dings, rust or debris in it. Without that the test bar can indicate the headstock as being out when it may not be. With the right conditions and some bad luck it could even indicate the headstock as being correct when it isn't. That might be very unlikely, but still not impossible. The OP did say it was an older lathe and reading between the lines it seemed it wasn't in the best condition. To me that makes it's headstock taper at least suspect it won't be in the best condition either. You could check the test bars runout of course and that will tell you if there's an internal problem with the MT. I've got test bars as well, and while there helpful there still only a static test the same as the Schlesinger tests are. That static testing can indicate there's a possible problem or the basic alignments are in the ball park. The end verdict is still that two collar test bar cut after everything else checks out. But Jan Sverre Haugjord on Youtube just posted a great video today about headstock alignment while fully rebuilding a total of seven Myford Super 7 lathes he's got. I'd have to consider Jan about the very best non professional machine tool rebuilder on YT at this point. He shows using a MT test bar, but obviously the lathes internal MT is in at least as new condition or with how Jan does things maybe even better.:-)

If there's a great deal of wear on the ways of the OP's lathe then at best he'd have to reach a compromise situation as far as adjustments and a true bed level condition. It's still worth attempting and the OP will learn a lot.

There's also more than a few items involved that greatly complicate getting the best average alignment to then get a lathe to cut as parallel as possible. Or to regrind those chuck jaws that the original question was about. That level and non twisted condition would be a good start. After that then checking the radial and end play on the headstock bearings would be my next step. If the bearings need adjusting or even replacement then any further tweaking is rather pointless until that's done. I'd probably then strip the carriage, cross and top slides, clean and readjust as well as possible including all the feed and lead screw end play, feed screw nut adjustment, gibs, the carriage retention guides and reassemble while repairing anything that needs it. Then do the same for the tailstock. That way your starting with the best possible condition the machines ever going to be in without doing a full rebuild. Checking the headstocks alignment then will provide some faith the test results should be accurate. Yes all this is a whole lot of work. It's also basic maintenance that's generaly mentioned in any machine tool user manual I've read.
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Re: Lathe setup question(s)

Post by neanderman »

I love this place!!! :)
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Richard_W
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Re: Lathe setup question(s)

Post by Richard_W »

curtis cutter wrote: Sat Sep 15, 2018 9:09 am First off, my old Enco lathe isn't much but at this moment it gets what I need done. Specifically, that is how to understand the operation of a lathe, tooling and materials. Not proud but it works. It is a good machine to learn on I believe.

My first question is, when I put a piece of 1/2" drill rod in my chuck and gently tighten it I can see movement in the rod at about 12" out from the chuck. I assume it is due to wear withing the jaws of the chuck, no surprise there. Am I most likely correct in this assumption?
With what you wrote it would appear you have a good chuck the way it is. If checking with feeler stock as Harold suggests and you find that the smallest gauge feeler stock doesn't fit between the material and chuck jaw. Use it as is.

Richard W.
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