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What is wrong with my 12'1/2" x 40" Cincinnati Tray Top Spindle?

Vladymere gr

Hot Rolled
Joined
Dec 10, 2008
Location
Charlotte, NC
I am a home hobbyist with a Cincinnati Tray Top lathe that I bought from my employer. Please don't refer me to the home hobbyist machinist site.

When I am cutting as I get closer to the chuck I will start getting a spiral in the cutting.

I have .003" of run out on the tip of the spindle when measured on exterior or interior of the L00 cone. I have a short video attached showing this runout. The video was made with the indicator tip contacting the end of the interior of the spindle. At the very end of the video I have the indicator on the end of the spindle exterior and I am lifting the spindle with a piece of plastic electrical conduit on the inside of the spindle.

I have tried tightening the headstock spindle bearings thinking that pulling the final spindle conical bearing in tighter to the races, I.E.-removing any play, might correct the issue. It did not correct the problem and if anything I now have the bearings to tight. The video was made with the bearings tightened.

As my title says, what is wrong with my spindle on my Cincinnati Tray Top lathe? Is it bent? Could this be a problem with the spindle nose bearing?

Gentlemen I seek your advice.

Vlad

Sorry Fellow, I am unable to attache the video. Sorry to have wasted your time.
 
Sounds like the bearings are loose or worn. Usually spindle bearings are pretty durable unless someone changed them with the wrong grade. If the spindle were bent you it would only run out when it's turning. I've worked on the clutches on that machine but not the bearings. Someone here might have a manual to help you see what you're up against if it is the bearings. Could be that's why they got rid of it. There is a forum here with manuals. BTW you're not wasting anyone's time, these are the most helpful group of people I've ever met. Good luck and keep us posted as to what you find.
 
I have .003" of run out on the tip of the spindle when measured on exterior or interior of the L00 cone.
.
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I have tried tightening the headstock spindle bearings thinking that pulling the final spindle conical bearing in tighter to the races, I.E.-removing any play, might correct the issue. It did not correct the problem and if anything I now have the bearings to tight.

Seems to be failing bearings. Do you know how to map "precession" of the first-failing element as the error excursion point migrates around the spindle's axis of rotation?
 
Wow, that's a lot of runout. Chuck up a test bar, put an indicator against it and push. Watch the needle. If it returns to zero it's probably not the bearings. Try a few different positions. If the runout increases as move away from the cone, its probably a bent spindle. Turn the rod 180 deg. to compensate for any chuck runout. Compare the two readings, they should cancel out to a consistent measurement (the delta would be runout). Read against the exterior of the L00 cone, the inside may not be precisely ground. The runout on the cone of my Tray Top is zero - dead still needle (I have to double check to see if it's even contacting the surface) I am using a B&S BestTest 0.0005 indicator). Pray it's the bearings. I don't know if you will ever find a spindle. If it is, work-arounds may be sending it out for repair/regrind, or maybe a adjustable 3-Jaw or a 4 jaw will allow you to compensate.
 
One can determine WHICH of damaged spindle or failing bearings without need of cutting any metal or mounting any "nose art" at all.

- sharpie-mark the high spot the indicator finds. If the spindle is EITHER of bent or the nose taper has a bulge, the high spot will always hit that same mark, one revolution or a hundred.

- if the high spot MOVES to a different "O'Clock" angle on a polar map - or relative to the first mark - for the next 12 to 20-odd revolutions before starting to repeat? One or more of the rolling-elements in the bearing is already dying.

The bearing is no longer centering the spindle. The precession is because the rolling-elements do not march at the same rate per each revolution as the spindle they carry.

BOTH are possible, of course. There will be overlap in what the above two tests reveal of that.

Needless to say the surfaces used to guide the DI have to be GOOD surfaces.

I use a Brian Miller test bar, #12 Jarno, second one 5MT inbound as I type. Those need LABORIOUSLY fitted to the spindle bore, because dings and divots there WILL assuredly be, and my DTI are 20 millionths and 10 millionths creatures.

Bought near-as-dammit for no OTHER work than to help decide whether a ~ $2,000 bearing set is essential. Or not.

20CW
 
Bought near-as-dammit for no OTHER work than to help decide whether a ~ $2,000 bearing set is essential. Or not.

20CW

Can totally relate to this - LOL. I put a ton of effort into chasing a 1 thou variation on my mill. Without a test bar as described, for the specific spindle taper, it's pretty much impossible given all the variables (least of which is a rock-solid tram). Results often contradicted root causes and the max runout (using drill rod) never got more than 2 thousandths but by then, I had to start considering knee ways, ER collet and holder and quill and level... Anyway, those test bars can cost a grand alone. My spindle replacement would be $1200 bare, almost $3K with a full set of matched precision bearings. Finally, I chucked up a quality EM and started making chips. The finish was excellent and the precision and accuracy far surpassed my expectations and needs (and much better than my previous mill with no notable runout so I moved on. :) Go figure...


Also, good test described!
 
Can totally relate to this - LOL. I put a ton of effort into chasing a 1 thou variation on my mill. Without a test bar as described, for the specific spindle taper, it's pretty much impossible given all the variables (least of which is a rock-solid tram). Results often contradicted root causes and the max runout (using drill rod) never got more than 2 thousandths but by then, I had to start considering knee ways, ER collet and holder and quill and level... Anyway, those test bars can cost a grand alone. My spindle replacement would be $1200 bare, almost $3K with a full set of matched precision bearings. Finally, I chucked up a quality EM and started making chips. The finish was excellent and the precision and accuracy far surpassed my expectations and needs (and much better than my previous mill with no notable runout so I moved on. :) Go figure...


Also, good test described!

Well . thank you! Mebbe I ain't ALWAYS off somewhere in Low Earth Orbit, after all!

But . .thing is ..providing they can still be drawn up so as not to jump about under pressure TOO damned much? One can actually "live with" the failing bearings! Rather well, too! A bent spindle, OTOH? "Not so much!

Here's how THAT works:

- The spindle roller bearing are "usually" selected by the designer to work in a manner similar to "hunting tooth" gearsets that have an off-by one or off-by few tooth count for their nominal ratio.

You don't get 4:1 or 3:1 rear-axles. You get 4:11 or 3:18 or some such.

Much the same on the "grand old" lathes that used rolling-element bearings and "in the beginning" had to STRUGGLE, and struggle HARD to match the glass-smooth work of the best of the plain-bearing lathes.

Upshot is that the "moving high spot" appearing under the tool at a different "O'clock" position each revolution lets a sufficiently broad, or sufficiently "many spring pass" persistent even when narrower tool-tip keep skimming-off a different high spot each revolution.

And there are a LOT of revolutions by tasking's end.

So it averages all that failing bearing error out.

Even when it cannot do as well with a bent spindle, that, too, has its "workarounds". Just not on a "company" lathe one is not permitted to mess with.

One doesn't even get a 13-lobed polygon. At the "real word" measurements to be hit, even that is smoothed-out by the cumulative movements of everything south of Polaris. The "pole star", not the Dodge.

If one had grokked that and then worked it to advantage? A wore-out 1930's Large & Shapely with FOUR THOU runout off the DTI turns bearing fits to one thou! Or even a HALF thou after I figured I was not being lied to, when told for the third time I was going to get my ASS whipped for "speeding".

Well. with a 23+ credit-hour Engineering course load DAYLIGHT hours, sleep when I am DEAD attitude, those second or third shift taskings would have seen me fall-the-f**k asleep out of sheer boredom get kilt and eaten by a large lathe!

So I figured fuggitdoll, I'll slow down as my Shop Steward and my Union "Brothers" insisted on, but "BLUEPRINT" all the Mike Foxtrot dimensions to keep meself awake!

Foreman could have married me once he saw that become "standard" and upped my tasking. No more boredom!

It ain't never just what you have between yer hands, is it?

:)
 
gmach10, I do have a manual. No clutch in this fellow except in the carriage.

Thermite, "Do you know how to map "precession" of the first-failing element as the error excursion point migrates around the spindle's axis of rotation? I don't know what this means. I graduated high school and then various company schools after that. This never came under my studies.

Your information inf post number 5 I do understand and can follow your diagnostic advice. I also understad what your saying in post number 7 but my turnings have a pattern marking in them. I will photograph this pattern and attach to this thread.

Mr.-Mike, I will follow through with your diagnostic advice as well.

Hopefully I can get back to the diagnostics tomorrow, Monday, or the day following that. I will report back what I find. I will also add still photos of what I am finding.

Hopefully whatever my needed repair is will be something I can save up for and execute. I'm on social security disability so money is tight.

Fellows, I really appreciate your responses and advice, particularly with the limited information I provided. Being a home hobbyist I also appreciate your not blowing me off and sending me to a home hobby forum. This problem is on what used to be a professional grade lathe and is of a nature that I think is above the typical home hobbyist forum for advice.

Thank you.

Vlad
 
gmach10, I do have a manual. No clutch in this fellow except in the carriage.

Thermite, "Do you know how to map "precession" of the first-failing element as the error excursion point migrates around the spindle's axis of rotation? I don't know what this means. I graduated high school and then various company schools after that. This never came under my studies.
More often used with gyroscopes and movement of astral bodies, yes! Sorry - I just don't have another word handy to describe what roller bearings DO in not coming back to the same place in but one single revolution.

but my turnings have a pattern marking in them. I will photograph this pattern and attach to this thread.
I hear yah, but there are so many OTHER things that brings in, I'd like to see if we can find out FIRST and off the "naked" spindle which and what you are dealing with.

.. something I can save up for and execute. I'm on social security disability so money is tight.
I've no idea what bearings cost nor how hard to find. The $1,000 and up are "super precision" for 10EE and the like.

The tray tops are "industrial" goods fair enough, but light lathes, not even "mediums", so unless the bearings are gone scarce, they should be less dear.
... above the typical home hobbyist forum for advice.
It isn't an "enemies" thing, nor "status", either. It is actually more about what folks in either place HAVE and have experience with.

No shortage of skill or craft, either place. Hand scraping is heavy as to hobbyists, here as well as "elsewhere", for example. Few others have any TIME to chase learning it. Even I (retiree) far prefer to hire it done. Even on "half rations" Social Security, given I stopped working in the USA and paying-in just before my 49th B'day.

:)
 
Fellows,

First let me thank all of you for your advice.

I didn't bother with photos. I did use a sharpie and mapped the high and low spots on the L00 cone. The high and low spots where consistent both inside and outside of the L00 cone.

I then ran the lathe for an hour at the highest speed with a face plate on the headstock so the L00 nut would not rattle and clang about. After running for an hour to warm things up I found the high and low spots had not changed. This seems to negate a bearing issue.

Mr-Mike's suggestion to apply pressure to the spindle and then see if the movement in the bearings returns to zero. I did this by inserting a piece of plastic electrical conduit inside the spindle to apply lift rather than chucking a piece of bar stock as Mr-Mike had advised.

DT38K is parting out a 12-1/2" Tray Top. Perhaps his spindle is good and at a price I can afford.

How does a piece of steel the diameter of my spindle get bent and the lathe not show signs of a crash? It appears to have been refurbished at one point. Perhaps it was crashed, the spindle bent and cosmetics corrected. I know that during my time with my employer, this lathe got very little use. There was nobody there that really new how to use it.

Vlad
 
Fellows,

First let me thank all of you for your advice.

I didn't bother with photos. I did use a sharpie and mapped the high and low spots on the L00 cone. The high and low spots where consistent both inside and outside of the L00 cone.

I then ran the lathe for an hour at the highest speed with a face plate on the headstock so the L00 nut would not rattle and clang about. After running for an hour to warm things up I found the high and low spots had not changed. This seems to negate a bearing issue.

Mr-Mike's suggestion to apply pressure to the spindle and then see if the movement in the bearings returns to zero. I did this by inserting a piece of plastic electrical conduit inside the spindle to apply lift rather than chucking a piece of bar stock as Mr-Mike had advised.

I've got some fair stout conduit around, but even so, the spindle bore isn't all THAT large, so I would not trust plastic electrical conduit to be all that predictable for this test.

How does a piece of steel the diameter of my spindle get bent and the lathe not show signs of a crash?

It may not have BEEN crashed in the sense we apply for a tragedy in-use.

It would not be the first lathe to have had the bad luck to be underneath something ugly as came off a travelling crane, or got into a conflict with a large raw part being maneuvered that became a massive hammer, even if NOT dropped at all.
 
Well fellows,

It is not a done deal but I may have found a replacement spindle for my lathe. Hope springs eternal. If am able to get it I will update this post later to let those that may be interested know how I fared.

I again want to thank all that responded to my request for help.

Vlad
 








 
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