It finally got the better of me... HELP!

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G

go_fish

Member
Joined
May 14, 2012
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54
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Melbourne/Australia
Hey guys,

Well my lathe has finally got the better of me. I've been having issues with run out and its driving me nuts trying to fix it.

I have a Zyto Mini Lathe, its made in like 1942 from what i can find. Its a belt driven lathe. It was given to me by my Grandfather before he moved interstate.

So at the spindle i get a reading of 0.01mm

When put the 3 jaw chuck on and i dialed the top of the chuck i get 0.15mm
So i chucked up some 0.950" (0.950"x 4.14")stainless steel and dailed it at the jaws for a reading of 0.15mm. When i move the dial gauge down to towards the tailstock i get a reading of 0.60mm.

Ive spent many hours trying to figure out the problem and how to fix it.

This morning i turned a small 2" bit of acrylic between centers(first time ive turned between centers) and i get 0.676" at one end and 0.675" at the other.

Sorry if my measurements are little all over the place, my dial indicators is metric and my Vernier Calipers are imperial.

Cheers Ben

(happy to chuck up some photos if needed.)
 
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A new 3 jaw will not be dead true, usually within .003 (.08mm). The jaws on an old one are usually worn, and will cause things to run out more the farther away form the chuck you get. As far as turning between centers, if that .001 difference is in a 2" length, pretty good for 90% of what is done because most stuff is less tha nthat. But you should be able to adjust the tail stock. Might need a pic, but look to see if it has set screws on each side, if so, you can adjust side to side there.
 
The bar may not be round or may have a bend in it. Rotate the bar to 90 degrees, 180 degrees and 270 degrees and measure at each position. If all measurements are close at each position then the chuck is suspect.

Chuckie
 
The bar may not be round or may have a bend in it. Rotate the bar to 90 degrees, 180 degrees and 270 degrees and measure at each position. If all measurements are close at each position then the chuck is suspect.

Chuckie
 
Ben, does the headstock spindle run on ball bearings or bronze bushings?
That would be the first thing I'd check to see if there is side-to-side lash.
Getting the headstock perfectly aligned with the tailstock is a difficult and tricky job. I bought one of those MT2-on-both-ends alignment tools but it really didn't help much. There are too many ways it can still be out.
 
Several things to investigate

Axial misalignment of headstock with the ways or the chuck (how does the chuck mount?). headstock tailstock misalignment, chuck mounted with the axis off center to the spindle axis.

Put as long a piece of known true rod in the chuck (TGP or drill rod) and run the dial indicator down the piece to see if the measurement changes, both on the side and on the top. This should identify an angular misalignment. Do the same between centers and see if you get the same or different results. If the same it is not headstock tailstock misalignment, if different is is in the headstock or chuck.

If the chuck is on crooked causing an angular misalignment it can be corrected in different ways according to how it is mounted. Same for being mounted off center if there is a wobble (out of round) at each end but no angular misalignment, easiest being to grind the jaws for some types of mounting.

Other things like worn bearings or other wear or a combination of all of these adding up together could also be the cause but these few are good places to start looking first.
 
IF your lathe bed is tweaked it will also cause run out. You need a level that can measure 0-.005 and check to see if the bed is true at both ends. It doesnt have to be perfectly level just out the same amount at each end.
 
Thanks for the replies guys!

Spindle is mounting using brass bushes. From memory there's not side ways play with it.

Is there a simple way I can check the tail stock to the chuck?

How would I check if the slide is misaligned to ways/bed?

I'll have to check a few things when I get home. Out for Mother's Day lunch.

Sorry if these questions seem basic, I'm self taught and only been going for 18months. Need to get this fixed and I'm currently turning reel seat inserts and hardware
 
Paul in OKC said:
A new 3 jaw will not be dead true, usually within .003 (.08mm). The jaws on an old one are usually worn, and will cause things to run out more the farther away form the chuck you get. As far as turning between centers, if that .001 difference is in a 2" length, pretty good for 90% of what is done because most stuff is less tha nthat. But you should be able to adjust the tail stock. Might need a pic, but look to see if it has set screws on each side, if so, you can adjust side to side there.
Click to expand...

The tail stock has one bolt in the middle which allows to move the tail stock left and right.

The other thing that springs to mind is that the tail stock and all slides have a steel ware plate is guess you could call it. It's mounted using 3 grubs screws. Maybe I've cocked out of one side.
 
Ok so heres some photos! Please look past the mess!

A full lathe photo
8731306956_1f7a38d5b5_c.jpg


Spindle and chuck mount
8731307104_d7bf63f2cf_c.jpg


Bed/ways?
8730187615_2783150a8f_c.jpg


8730187711_51f7c6f8db_c.jpg


Tailstock and ware plate?
8731307506_ef10204808_c.jpg


8730188479_386a1c712d_c.jpg



I hope that you guys can make some soft of sense from these photos.

Benny
 
Dale Allen said:
Ben, does the headstock spindle run on ball bearings or bronze bushings?
That would be the first thing I'd check to see if there is side-to-side lash.
Getting the headstock perfectly aligned with the tailstock is a difficult and tricky job. I bought one of those MT2-on-both-ends alignment tools but it really didn't help much. There are too many ways it can still be out.
Click to expand...

Dale,

Headstock spindle runs on bronze bushings, checked for play left/right/up/down all seems well to me no play.
 
Sorry to keep posting photos. I do as much as i can while my 8month old is quite and happy.:biggrin:

I just chucked up the pen mandrel and here is what i got.

8730266763_3a4025785a_c.jpg


Seems i have a high spot between jaw 2 and jaw 1

8731378214_dbaa890f99_c.jpg


8730253775_b4151677ec_c.jpg
 
Ok so all that stuff that is on the mandrel could cause some of that couldn't it? How much if you take some scotch bright and clean that mandrel up? Then retest it. I can see from the images that the end close to the chuck is nice and clean and the other end is not?
 
mikespenturningz said:
Ok so all that stuff that is on the mandrel could cause some of that couldn't it? How much if you take some scotch bright and clean that mandrel up? Then retest it. I can see from the images that the end close to the chuck is nice and clean and the other end is not?
Click to expand...

Mandrel cleaned and rest. 0.05mm at the jaws 0.12mm towards the tail stock. Both high points are in the same spot
 
A pen mandrel is not assured as accurate, mostly just treaded common mild steel round stock. You could verify -to some degree- the measurement by using a different one to see if the readings are the same with both,

Try getting a piece of 3/8 or so drill rod or (better) turned ground and polished (TGP) rod and checking it that way to get a truer measurement. Measure along the top as well as the side, and run the indicator down the rod on the cross slide to see if it is a steady change in measurement (hard to determine with something as roughly made as a pen mandrel).

Also measure the shoulders on the chuck and the spindle to make sure they are still true, on an old machine there is no telling what they have been through, The spindle could even be bent (least likely problem), that would show up in point wobble of a center mounted in it (be sure the center and the spindle bore are both perfectly clean and have no burrs that could cause a problem). If the spindle or chuck shoulders are dinged, that is reasonably easy to correct but a spindle problem not anywhere near as easy without just replacing the spindle.

How are you measuring bearing play? (If the bearings seem to be perfect on a machine that old they have probably been replaced at some point and there is a possibility of spindle misalignment being introduced when they were). Busings on a spindle need to be put in undersized and line bored to guarantee they are true to the axis (a little complicated but not excessively).

(The problem is probably something that can be adjusted out, not something as major as I'm describing since I don't know exactly how you have conducted troubleshooting so far and I'm sort of superposing my approach on the process as if the results were from it.)

The chuck jaws might be causing the problem if they are holding the piece off axis, they can be ground true pretty easily with a Dremmel or similar tool wit a grinding stone and a jig to put it on the cross slide.

That machine looks like something that could turn out some well done parts when adjusted and aligned properly.
 
frank123 said:
A pen mandrel is not assured as accurate, mostly just treaded common mild steel round stock. You could verify -to some degree- the measurement by using a different one to see if the readings are the same with both,

Try getting a piece of 3/8 or so drill rod or (better) turned ground and polished (TGP) rod and checking it that way to get a truer measurement. Measure along the top as well as the side, and run the indicator down the rod on the cross slide to see if it is a steady change in measurement (hard to determine with something as roughly made as a pen mandrel).

Also measure the shoulders on the chuck and the spindle to make sure they are still true, on an old machine there is no telling what they have been through, The spindle could even be bent (least likely problem), that would show up in point wobble of a center mounted in it (be sure the center and the spindle bore are both perfectly clean and have no burrs that could cause a problem). If the spindle or chuck shoulders are dinged, that is reasonably easy to correct but a spindle problem not anywhere near as easy without just replacing the spindle.

How are you measuring bearing play? (If the bearings seem to be perfect on a machine that old they have probably been replaced at some point and there is a possibility of spindle misalignment being introduced when they were). Busings on a spindle need to be put in undersized and line bored to guarantee they are true to the axis (a little complicated but not excessively).

(The problem is probably something that can be adjusted out, not something as major as I'm describing since I don't know exactly how you have conducted troubleshooting so far and I'm sort of superposing my approach on the process as if the results were from it.)

The chuck jaws might be causing the problem if they are holding the piece off axis, they can be ground true pretty easily with a Dremmel or similar tool wit a grinding stone and a jig to put it on the cross slide.

That machine looks like something that could turn out some well done parts when adjusted and aligned properly.
Click to expand...

Frank,

When i dialed the spindle i got a reading of 0.01mm or there abouts.

Unfortunately when it comes to understand what your explaining i have a very rough idea.

The best i can do is redial the spindle, screw the backing plate on and dial. Reassemble the chuck to backing plate and dial the chuck. Happy to take photos and video of my findings.

If you tell me where to put the dial, i will dial it and let you know. Happy to trouble shoot how ever you would like me too.

The problem is probably something that can be adjusted out
Click to expand...
Ill have to take a photo of something that is really concerning me, this could be the root of the problem.

Im finding that being self taught and not knowing what everything is called is going to make things a little harder, but if you're will to bare with me im sure we can get the problem worked out.

Until tomorrow after the 8-5pm slug, im going to call it a day.

Thank you everyone for your help this far!:biggrin:

B
 
As the chuck end, looks like you could loosen the bolts and possibly tap as you indicate. On the tail end you can adjust the tail stock in and out. The line on the front is an eye ball mark. Look on the back side to see if there is a screw. If you chuck up a piece and turn it, measure it at the chuck and the tail end. If smaller at the tail, use your indicator and move it away from you half the difference. If bigger, then half toward you.
 
Looking back at the tail stock pic, looks like you would loosen the nut on the top of the base to move it. Back where the 'slot' is should be a screw, if not tap lightly.
 
Ben; A good suggestion would be to take a look at the PDF file "Introduction to 9x20 Lathe operations". These guidelines are specifically for the 9x20 class of lathe, but most lathes have similar controls and parts.

Also I will mention that a good cleaning of all the parts of the lathe should be in order. It only takes a little trapped gunk to throw everything off.
 
randyrls said:
Ben; A good suggestion would be to take a look at the PDF file "Introduction to 9x20 Lathe operations". These guidelines are specifically for the 9x20 class of lathe, but most lathes have similar controls and parts.

Also I will mention that a good cleaning of all the parts of the lathe should be in order. It only takes a little trapped gunk to throw everything off.
Click to expand...


Randy,

Thanks for the link! Everything got a good clean last night after i took those photos. I felt bad looking at those photos and cleaned the lathe
 
Hopefully this is make some sense to someone.....

Ill let the photos do the talking.

8734955646_276ca6ae2a_c.jpg


8733836873_76a845be9b_c.jpg


8734955902_5b27d7067a_c.jpg



Im only assuming here, but maybe theres a problem with the chuck?
 
Most likely just worn. If the chuck fits on a little 'boss', you could machine a tiny bit off and just lightly snug the bolts and bump it in. Make sure the plate is true on the face as well. Might need to take a light cut on the face as well.
 
IF you put a piece of stock in the chuck say 25mm or larger about 50mm long, make a light cut(s) that cleans the entire piece. DO NOT use the tail stock for support. Then dial indicate that piece at the chuck and at the end. What are your results?
 
mredburn said:
IF you put a piece of stock in the chuck say 25mm or larger about 50mm long, make a light cut(s) that cleans the entire piece. DO NOT use the tail stock for support. Then dial indicate that piece at the chuck and at the end. What are your results?
Click to expand...

Turned a bit of ally. 50mm long x 28mm. 0.03mm at the jaws. 0.05mm towards the tailstock.

Ben
 
hmm .1mm is..00393 imperial IF your out o round .03mm that is.00118 imperial. .05mm is .00196 both are acceptable in an older machine. OR are you o.o.r .3 and .5 YOu could have an issue with headstock or spindle alignment but more likely wear on the bronze bushings.
It could be either in the front or in the back or both. If you set your DI up horizontally on the spindle or chuck and push it back and fourth how much does it move? if any.
 
mredburn said:
hmm .1mm is..00393 imperial IF your out o round .03mm that is.00118 imperial. .05mm is .00196 both are acceptable in an older machine. OR are you o.o.r .3 and .5 YOu could have an issue with headstock or spindle alignment but more likely wear on the bronze bushings.
It could be either in the front or in the back or both. If you set your DI up horizontally on the spindle or chuck and push it back and fourth how much does it move? if any.
Click to expand...

DI set as you described. I can push it 0.04mm past either side of 0.00mm with out to much trouble.
 
You will not be able to over come that play, without some serious rebuilding and its probably not worth it. Lock down the tail stock and extend the quill and do the same thing. That will tell you how much wear is at that point.
 
If your going to use this lathe for most home and hobby turning the wear wont be a problem. If your thinking about making space shuttle parts mmm wont happen. If you dont have or cant borrow a preccision ground bar to put between centers and measure you will need to turn as long a bar as you can at least 25mm in diameter or larger, using light cuts (to minimize deflection) . measure the 2 ends and then start adjusting your tail stock. Until they are the same. As I mentioned earlier in the thread if the ways of the bed are not true, even a slight twist will throw off the tail stock. Mostly we level the lathe ways but as long as they are both readings are level or out of level the same there should be no twist. You might check the level of the ways at both the headstock and tailstock as best you can. You can shim one side at the tailstock if you need to. If they are the same then you can adjust your tail stock to where you need to.
 
Last edited:
mredburn said:
You will not be able to over come that play, without some serious rebuilding and its probably not worth it. Lock down the tail stock and extend the quill and do the same thing. That will tell you how much wear is at that point.
Click to expand...

Tailstock locked down and quill extended. 0.01mm either side of 0.00mm with out to much hassle.
 
mredburn said:
If your going to use this lathe for most home and hobby turning the wear wont be a problem. If your thinking about making space shuttle parts mmm wont happen. If you dont have or cant borrow a preccision ground bar to put between centers and measure you will need to turn as long a bar as you can at least 25mm in diameter or larger, using light cuts (to minimize deflection) . measure the 2 ends and then start adjusting your tail stock. Until they are the same. As I mentioned earlier in the thread if the ways of the bed are not true, even a slight twist will throw off the tail stock. Mostly we level the lathe ways but as long as they are both readings are level or out of level the same there should be no twist. You might check the level of the ways at both the headstock and tailstock as best you can. You can shim one side at the tailstock if you need to. If they are the same then you can adjust your tail stock to where you need to.
Click to expand...

I only use my lathe for turning pens and reel seat inserts and hardware.

What would I have to do to rebuild? Having bronze bushings made wouldn't be to much of hassle. Will have to speak to a friend of mine and see if he machine machine me a PGB. He owns an enginering bussiness with a heap of cool toys. Only problem is its a fair drive.

Thanks so much for your help! I've spent many hours talking to different people and couldn't come to a conclusion.

Ben
 
Ben, it looks like you have the Zyto-16 from what I can see on this link:
Zyto Lathes
Somewhere in there it said that the replacement of the headstock bushing should not be much of a problem.
But then that was a good many years ago.
 
Paul in OKC said:
Can you just snug the bolts down a tad? Not to the point of binding, but may take up some of the slack, especially if they are split.
Click to expand...

those bolts are locked down, :frown:

I think for now, ill adjust the tailstock to the same measurements as the chuck.

Ive had the all clear to have some bronze bushings made from a mate. So ill have to measure them.

Thanks for your help! Greatly appreciated!
 
In your post #21, 3rd picture down, it looks like there is weld on the back of the plate the chuck mounts to. Is this weld or an optical illusion?

Sandy.
 
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