Lathe bed wear question

Hi, new to the forum and new to owning a lathe. I recently got a Logan 12" and have been learning to use it. I decided to try a test bar and get my tailstock lined up which i think i had gotten pretty close but in doing so discovered i was getting a pretty big taper towards the chuck end for about 3-4" then it straightened out and had about a half thou from there to 9 inches.

The measurements i got on one test using the tailstock were:

0" - 0.8447"
1" - 0.8510
2" - 0.8523
3" - 0.8514
4" - 0.8497
5" - 0.8498
6" - 0.8496
7" - 0.8496
8" - 0.8494
9" - 0.8497

On a shorter piece with no tail support i got the following:

0" - 1.9294
1" - 1.9352
2" - 1.9381
3" - 1.9382


So in both cases im getting a good bit of taper towards the chuck and straightening up after a few inches. I checked for bed wear using a technique i saw on here putting a dial indicator on my tailstock and sliding it along with the indicator on the carriage ways, flat and V ways both showed about 5 to 6 thou wear difference between the tailstock ways. The wear was greatest right up closest to the chuck and kind of matched the results from above in that it seemed to really come in most around the 4" range from the chuck.

I didnt think this really seemed like that much wear compared to some other posts ive seen. What do you think about this scenario? Is there something i can do to help with the taper im getting towards the chuck end? It seems im getting more taper than id expect for the amount of wear it seems to have. Maybe something else i might be doing wrong?

Do your test between centers if you want accurate results . Doing it using a chuck on one end introduces errors that the chuck mounting-jaws etc may have.

Did you make absolutely certain that your cutting tool point was on center? We just had a guy that was worried about taper on his lathe in another thread - he discovered the tool was below center, and setting it at the correct center height almost completely solved his taper problem. The farther off center the tool is the more that wear will show up as a taper.

From what you wrote, I gather you made a test bar, not bought a test bar. That would leave so many possiblities open to a problem, as there could be a number of things.

I'd start with leveling your lathe.

Then buy test bars that would fit the taper of spindle in head stock. And one for the taper of tail stock.

Put a mag base dial indicator on the compound. Run the compound back and forth reading 12 oclock and 9 oclock on test bars. Roll spindle by hand to check run out, etc.

If your using a chuck now, is it a 3 or 4 jaw ? There's a lot of factors could contribute. If you buy some precision test bars, use an indicator, it'll answer more questions. Need tapers clean in HS and TS clean though, might need finishing reamers to gently clean them for test bars to get good reading, any little ding or bump will throw the reading off.

Not sure what tapers you have, but as an example, you can get mt3 test bars cheap, its made in india, but'll get you there.
3MT Lathe Alignment Test Bar MT3 Alloy Steel Over All Length 335mm 13-3/16 Inch 7101363340345 | eBay

Chrisfol82 said:

Maybe something else i might be doing wrong?

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Not "wrong" Just not "yet".



Besides advice you have already been given, most of the wear is not where you can see it.

6 thou on the visible inverted vee ways can be matched with several times as much wear on the out-of-sight mating underside of the carriage.

Worse, they don't simply settle-down level and in full bearing end-to-end. The underside of the carriage tends to wear more at the ends, developing a "rocking horse" shape.

You will want to try to measure that by applying sandbags or something similar at alternate corners in turn. Tool loading can make the carriage rock on heavy cuts, light cuts "maybe not so much".

So you have a useful-enough lathe.

You just have to decide how far to go as to learning how to compensate for its wear, and how much of the wear effects you can reduce, economically.

Rebuild to OEM spec can be done as a "labour of love". Or even a learning exercise. It CAN be more about labour than cash spend if you scrape it.

Bed grinding costs about as much for a cheap lathe as an expensive one, so doesn't make good economic sense at all. And then one STILL has scraping to do.

End of the day, the time cost of it is more than a lathe in better condition might cost.

Light lathes, low value, hobby use?

It most often makes sense to fix only the easy stuff, then just learn to work around the negative effects of the rest.

It's a nuisance of sorts, compensating. Then again, also a valuable skill.

Essentially EVERY machinist who ever worked for someone ELSE.. had a "company lathe" under his hands. And hardly EVER was it in the best of condition, let alone brand-new and "perfect".

As already indicated, make sure you are cutting on center.

If you want to compare cuts with and without the tailstock, or in any other way----

USE THE SAME DIAMETER STOCK. Small diameter stock will show more taper from bed wear than larger diameter stock.

FYI Setting the tool slightly above the centerline can partially compensate for bed wear as the tool will increase the depth of cut as it drops. How much depends on the diameter of the stock.

Thanks for all the replies and advice. To answer a few questions, im using a 3 jaw and turning a bar down, then measuring diameter with a micrometer in one inch increments. On the longer smaller diameter bar i have it in a live center in the tail, and the shorter bar i used larger diameter to keep more rigidity without using the tailstock, but same process in that id take about a 10 thou cut then measure diameter in one inch increments. I have a 4 jaw too but i had been using the 3 jaw since im taking cuts to measure what the lathe is actually making, not trying to center up an already precision test bar.

Tail is a MT2, head i have an adapter to take it to MT 2 as well but haven't used that at all yet.

I kind of thought that wear on the underside of the carriage wouldn't effect cut as much since it is moving with the carriage, but i can see how unevenness could cause issues from rocking. There is definitely a good bit of wear on the underside too.

Im not 100% certain my tool is dead center, so that might be the next best thing to try a few more cuts trying to get the tool better centered, or slightly high as suggested. Ill try that and check again.

I just got it to learn on and use for hobby work, not trying to do anything precision at this point, but i am trying to get it set up as best i can and get some advice on making sure it is working to the best of the lathes ability. Someday i may try to do some bolt action truing/rebarreling if the lathe seems up to it, or if i think im capable.

Ill try some more things and see if i can make some improvements.

I plan on making some mounting pucks out of steel with some jacking screws, as of now i have the jacking screws on the lathe but sitting on wood blocks and leveled as close as i can get it with a cheap carpentry level. My brother has a machinists level ill borrow to get it leveled more accurately once i make the steel feet.

Leveling a lathe is less about getting it level and more about adjusting the ways into a shared plane. Any results from a level are merely a starting point.

After leveling the lathe, you follow up by adjusting the tail end so it no longer cuts taper (more accurately stated, cuts an acceptably small taper). Do this with out tail stock support, or you will be measuring tailstock alignment, not head to bed alignment.

Once the head stock and bed are aligned, then you can dip a test cut between centers to see if your tail stock is centered. Between centers because the jaws of your check may not be parallel with the axis of the spindle and you only want to measure one thing at a time. If the tail stock is pulling the end of the bar in one direction or another the results could be misleading because you won't know the cause of the taper.

There are many threads here on lathe leveling methods have a scan through a few to see better descriptions than mine.

Chrisfol82 said:

Thanks for all the replies and advice. To answer a few questions, im using a 3 jaw and turning a bar down, then measuring diameter with a micrometer in one inch increments. On the longer smaller diameter bar i have it in a live center in the tail, and the shorter bar i used larger diameter to keep more rigidity without using the tailstock, but same process in that id take about a 10 thou cut then measure diameter in one inch increments. I have a 4 jaw too but i had been using the 3 jaw since im taking cuts to measure what the lathe is actually making, not trying to center up an already precision test bar.

Tail is a MT2, head i have an adapter to take it to MT 2 as well but haven't used that at all yet.

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Your mileage may vary, but 3 jaws are inherently inaccurate. They are best used for cleaning and polishing shafts, or rough work, where accuracy is not an issue.

When you get in the habit of using an independent 4 jaw, you will probably not use a 3 jaw much again.

If you get an mt2 test bar. You can swap back and forth between HS and TS to get basic checks and alignments done.

If you don't already have an an mt2 dead center, get one. Stick test bar in HS and dead center in TS. Bring TS with dead center up close to test bar in HS. The test bar will have a mating hole in the middle that dead center in TS can enter. That'll help align TS to HS.

With dead center in TS, check with quill extended and retracted, when aligning to the test bar in HS.

Edit: if you center up your homemade test bar in the four jaw, using a dial indicator to get it really zero'ed in. Re-run your test. Might find an interesting new result too.

Concur that a test held between a chuck and center is not a good test. You need a longer/heavier piece of stock for your chuck held test though. >1.5" x 8-10" aluminum works well, heavy wall tube even better.

I'd forget about the TS alignment for a minute and do some more assessment of the level and HS alignment. A test bar does make things easier but a precision level is more important. A level will quickly tell you if you've got bed twist and wear. It is really the first step. Keep in mind that on a 45 degree V-way the impact on diameter of a turned part is significantly less than the amount of wear. 0.005" would be almost negligible on the cut. Though as has been said the carriage may have equal or more wear. You certainly have something odd happening in that first inch though.


Many lathes have HS that can pivot and do not sit directly on the ways, a Logan I would guess is one. If this has been bumped out you will turn a taper. If you are lacking a test bar and level another quick and easy check is to do a facing cut on a large diameter disk, say like 5" or more. Then run your an indicator across the just cut face. It will be very near zero on the front half you just cut but as you cross center it may show concave or convex in the back half. All lathes are designed to cut a very minimal concave facing cut, something like 0.001"/12". My first lathe was an 80's import and turned 0.001"/inch taper and a matching error in the facing cut, so I aligned the HS and it then did very will in both tests.

Well i had a chance to mess with the lathe again some today. First thing I did was made up a burr file as i had read about on here, and went over my ways some and knocked down a few dings in the ways.

Then i made a facing cut on a 3" piece of steel bar, 3" was the biggest i had, first cut i was getting about a one thousandth concave that was pretty even across the whole piece from 0 to .001 back to 0 at the other side. I locked in my compound and just made sure everything was good and tight and did a couple more cuts and got down to about a half a thou over the 3" facing cut.

I dont have a dead center yet or a drive dog to turn between center so i did my test with the 9" ~1" diameter bar again in my 3 jaw with slightly better results, about .004 total difference between highest and lowest. I messed around with tool height, raised it about 0.002, then dropped it about .002, diameter varied from about .0035 to about .006, so some variation there, but i do probably need to optimize my tool height a little better.

Then i decided to rechcek my tailstock and dialed it in again with a little different method than i had used before, and it was a good bit out mostly in height. I got it to within a few thousandths and tried another cut. This one was much better, kind of football shape with total variation of just over one thousandth (.0012)

So its gotten way better than when i started. Im hoping to borrow a machinist level here in the next few days so ill level it and try again and see if i get anymore improvement. I made two steel feet, just need to make two more to get my back leveling screws off of wood on on to steel feet as well. Thanks for all the advice so far.

So when aligning my tailstock i had put some shims in the first time i tried to align it, but the second time realized i was too high and took the shims out. I was still slightly high though even without any shims by maybe 2 or 3 thousandths. Is there anything more you can do if you have no shims and still high? sand the base down?

It is really basic for a lathe to cut less then .001" taper in 6 or 7 inches work unsupported, just hanging out the chuck.
If it cant do that, the machine is not so useful for me any way....

Chrisfol82 said:

So when aligning my tailstock i had put some shims in the first time i tried to align it, but the second time realized i was too high and took the shims out. I was still slightly high though even without any shims by maybe 2 or 3 thousandths. Is there anything more you can do if you have no shims and still high? sand the base down?

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I'm not there seeing what you are seeing, but it is unusual for a tail stock to be too high. Over time with natural wear, they always end up low, and need to be shimmed up. For you to have no shims and still be too high is really odd.

You mentioned you did not have a dead center. Just curious how you are checking height ?

hello Chrisfol,
I'm not sure if anyone has mentioned this, but it is extremely important to "level" a lathe, especially longer, larger lathes. This task should be undertaken at least every 6 months or so.

Chrisfol82 said:

Well i had a chance to mess with the lathe again some today. First thing I did was made up a burr file as i had read about on here, and went over my ways some and knocked down a few dings in the ways.

Then i made a facing cut on a 3" piece of steel bar, 3" was the biggest i had, first cut i was getting about a one thousandth concave that was pretty even across the whole piece from 0 to .001 back to 0 at the other side. I locked in my compound and just made sure everything was good and tight and did a couple more cuts and got down to about a half a thou over the 3" facing cut.

I dont have a dead center yet or a drive dog to turn between center so i did my test with the 9" ~1" diameter bar again in my 3 jaw with slightly better results, about .004 total difference between highest and lowest. I messed around with tool height, raised it about 0.002, then dropped it about .002, diameter varied from about .0035 to about .006, so some variation there, but i do probably need to optimize my tool height a little better.

Then i decided to rechcek my tailstock and dialed it in again with a little different method than i had used before, and it was a good bit out mostly in height. I got it to within a few thousandths and tried another cut. This one was much better, kind of football shape with total variation of just over one thousandth (.0012)

So its gotten way better than when i started. Im hoping to borrow a machinist level here in the next few days so ill level it and try again and see if i get anymore improvement. I made two steel feet, just need to make two more to get my back leveling screws off of wood on on to steel feet as well. Thanks for all the advice so far.

So when aligning my tailstock i had put some shims in the first time i tried to align it, but the second time realized i was too high and took the shims out. I was still slightly high though even without any shims by maybe 2 or 3 thousandths. Is there anything more you can do if you have no shims and still high? sand the base down?

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Be patient, mostly. Look how fast you are getting to know your machine, already!



- a burr is raised. It affects mating or sliding surfaces, is the enemy of accuracy.

- a ding or divot is depressed, It doesn't affect fit nor accuracy. It MAY have a detrimntal long-term effect because it can trap sharp or abrasive particles, drag them to where they increase the rate of wear. Keep such a surface clean and lubed, not really a problem if the whole bed of a lathe had prominent rust pits.

- Most lathes are set up to intentionally face slightly concave, not risk slightly convex. It's what works.

- You seem to be at or near "typical" precision, and within easy range of compensating. On most things. Not just facing.

That lathe can do PLENTY of good work. Machinists have ALWAYS had to compensate. We did not own the lathe, had to use whatever the company put us in front of.

Ignore the drama-queen troll posturing about how "perfect" he and his machines allegedly are. He's a nut-job after attention, barely has a klew.

Run what you have. You'll be fine. Not a lot of choice, anyway, is there?




First thing to suspect as to your TS, is that your method of measuring is imperfect.

START your process of leveling with an ignorant carpenter's level.

Ten-dollar Chicom Dead Center NEW is better than NOTHING. Testing don't put any wear on 'em. Get "something". Otherwise yer just jumping back and forth through yer own patootie.

Dog you can make, and quickly. A jaw on the chuck can push it.

"Perfect" TS are nice, but not a show-stopper class necessity.

You can "move" the center, same as we had to do on "company" lathes. Slip a strip of Kraft paper or cig-pack foil down along the useful side of the taper as you insert it into the socket, push the center to a better place, do the job. Try it and see.

Drilling with the TS instead of the carriage? You want a torque reaction control device REGARDLESS. Pipe wrench on a jacobs chuck is really UGLY. DAMHIKT!

Make something nicer. Otherwise, drills can tear-up the TS key even if they do not damage the taper.

Second possibility is that when you put it back together you raised burrs or otherwise did not get a close mating fit.

Take your time. Do your research. "First, do no HARM!"

Take advantage of each small gain and keep on looking for more gains, large and small. KEEP NOTES!

It will come good. It has already started to come good.

this last time i checked height i did it by putting my mag base on the chuck with dial indicator point on the live center flat section before the taper and rotated the chuck, adjusted left and right screws to within a thousandth or so and with no shims i was a tad high. This is actually not the original tailstock but i believe to be the right one for this machine. Ill investigate more on this end but i was pretty pleased to have brought my diameter variance down as far as i have while still not being perfect on the tailstock and also not really being well leveled. Need to try another test without the tailstock though and see how it does on a shorter larger diameter unsupported piece.

I still plan to level the machine better than i have, but like i said im just waiting to borrow a good machinists level and finish making up some good solid feet and jacking screws. But given ive only leveled it so far with a carpentry level id assume i have some room for improvement in that area. Also been good practice in trying to get a nice surface finish on the feet im making.

As for my burrs and dings, i have quite a few of each, so i was trying to knock down the burrs kind of as you said to make sure im not riding up on a burr throwing things off. This seemed to help a little on its own. The edges of the ways seemed to have some burrs that definitely got knocked down a little. Thanks for the advice thermite, and i feel much better with how its doing than a week ago and as you said ive learned alot about the machine in the process.

Chrisfol82 said:

ive learned alot about the machine in the process.

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If a TS swap was done that actually DID leave you high? GIVE THANKS!

That's going to prove a stroke of VERY good fortune as to making correction a great deal less work when you progress towards it.

TS base usually get a bit of drop from heavier wear at the front, also a curve, rocking-horse style. And then the ram/quill wears at the nose as well.

This one MAY have just been dropped in place. or it MAY have had the sole corrected when it was fitted "etc."

Call it "usable' for now. Go after more pressing problems. Come back to it when other fires have been pee-ed on.

Two things....I put a magnetic base dial on the chuck and checked the tailstock......WRONG.....I think the tailstock is high..WRONG....all you are seeing is the spring in the dial base from gravity....Your tailstock is low,by how much will need to be measured.

john.k said:

Two things....I put a magnetic base dial on the chuck and checked the tailstock......WRONG.....I think the tailstock is high..WRONG....all you are seeing is the spring in the dial base from gravity....Your tailstock is low,by how much will need to be measured.

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It surely isn't definitve, given position on a worn bed has an influence, but the oldest and quickest in "HTRAL" onward is to:

- TURN a point on a bit of stock in a collet or chuck.

- Put a(ny) decent center in the TS

- gently slide them together and SEE if they are even CLOSE.

Plenty more ways to check. OP is just getting started.

Imperfections? Aren't there ALWAYS?

Usable machine ANYWAY?

Seems so.

Well, old Rooster Fish Bill is a verified Bull Shitter, best take that in consideration, he has never made a part on a lathe.




"It surely isn't definitve, given position on a worn bed has an influence, but the oldest and quickest in "HTRAL" onward is to:

- TURN a point on a bit of stock in a collet or chuck.

- Put a(ny) decent center in the TS

- gently slide them together and SEE if they are even CLOSE.

Plenty more ways to check. OP is just getting started.

Imperfections? Aren't there ALWAYS?

Usable machine ANYWAY?

Seems so."