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Timken Bearing fit question

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Abear

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#1
I'm in the middle of swapping my babbit headstock with a timken headstock (10A-2B). The timken bearings are very tight fit on the spindle. The spindle came with the main bearing (closest to the bull gear) already installed. When doing dry fit assembly, the bearing on the opposite side will only slip on over the threads, once they get to the smooth part of the spindle, they stop. Should the bearings be press fitted? I'm cautious to apply force or slight tapping with mallet, I need to be able to remove them for the actual install in the headstock. All other components, gears, pulleys, and collars easily slip into place without force.

appreciate any advise...
thanks,
Jude
 

Moderatemixed

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#2
I’ve rebuilt several head stocks and never had to press the bearing on the left. The bearing on the right is pressed on. For that reason I have not removed the bearing on the right (nearest the spindle nose, threaded end). Fortunately my bearings have been in good shape and have not required replacement. When putting it all back together, everything is a slip fit, or on occasion a tap or two, but never as you describe.


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benmychree

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#3
Perhaps you should measure the mating parts and see what sort of fit there is, and also check to see if there are any burrs that are making it difficult to assemble. On my lathe (not like yours, the rear spindle bearing does require a slight press to assemble, I'd think that should be about metal to metal, that is they should measure the same size. On a lathe, having a free sliding fit for the bearing inner race would allow radial movement that would lead to inaccuracy of the spindle's running.
 

tertiaryjim

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#4
Suggest you measure the bearing bore and fit. Probably shouldn't have more than 0.0002" interference but I would think 0.00005 would be best.
If its in that range you can heat the bearing in a oven to 120deg and it will slip on. 100deg for a very light press fit.
I always rub anti-sieze on shaft and bore but it has to be so thin that it's almost invisable.
Edit: I should have said 120 or 100deg above ambient temperature. Big difference.
 
Last edited:

markba633csi

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#5
As John mentioned the left bearing should be a light interference fit but it may require you to put together a threaded rod and spacer tool to
pull it together. That would be preferable to hammering it in. Use oil too.
Mark
 

Rooster

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#6
Greetings, i have a Atlas 618 which i installed 2 new bearings on. Like Mark said, threaded rod with a spacer tube was necessary to get the left bearing on.
 

wa5cab

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#7
While it is of course possible that the people who didn't have to press the left bearing cone on just didn't mention it, everyone until this thread who has commented on the left cone fit has said that it was tight. This includes posts both here and on the Atlas-Craftsman group formerly on Yahoo and now on groups.io. And yes, it does make determining where the zero end-float point is more difficult.
 

Kernbigo

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#8
The left bearing has to be a slip fit or
you will not be able to set the bearing clearance.
 

woodchucker

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#9
In general I have used a hot plate to heat bearings so they expand to fit on shafts. I am not talking spindles, just in general on tight fits.
 

cdhknives

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#10
I know when I changed my bearings I thought it was all tight until strange things started showing up in my cuts...and I had a good 2 turns of the nut worth in looseness back...so recheck after running for a while no matter what.
 

Abear

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#11
Thank you all for the feedback. I’ll measure the spindle and the bearings and report back what I find. I had considered heating the bearings but wasn’t sure of how much to heat, so thank you tertairyjim for that info. I’m eager to complete the assembly, maybe tonight after the kids karate classes.

Thanks again
Jude
 

BtoVin83

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#12
In a single cup installation Timkens can stand a lot of press fit on both cone and cup because the final take up is the end play, what they do not tolerate is out of round
 

wa5cab

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#13
As I wrote earlier, although one would think from the way in which the end float is adjusted that the cone is going to be at most a light push fit on the spindle, any number of reports indicate that isn't always the case. I would make a puller from a length of 5/8" threaded rod (UNF if you can find it), a length of structural tubing with ID just slightly larger than the left end of the spindle, a shoulder washer to fit the tubing and one to fit the right end of the spindle. and some coupling (long pattern) nuts. Or put the cone in something like a roasting bag and immerse it in boiling water for 15 or 20 minutes. Carry the pan with the bearing to the lathe, take the bearing out of the water and out of the bag with an oven mitt and slide it onto the spindle and hold it and the spindle together until it cools off and locks. Load the spacer, gear and threaded collar on the spindle. Use a dial indicator to check end float, tightening the collar a tooth at a time until it goes to zero. Then two more teeth for preload and tighten the set screws.
 

Kernbigo

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#14
I rebuilt high speed spindles and also have rebuilt the spindle you are referring to with a press fit on the rear bearing you won't be able to adjust the spindle end play. Tha t rear bearing has to be a push fit in order to adjust.
 

Abear

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#15
I managed to measure the bearing and the spindle tonight. The bearing was 1.2450 and the spindle was 1.2490. I heated the bearing and was able to get everything put together. The bearing was a tight fit, I was able to pull it on with a threaded rod and spacer tool. Thanks for the help...
IMG_7747.jpg IMG_7749.jpg IMG_7748.jpg
 

Rooster

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#16
Glad you made out. That's one fine looking head-stock.
 

MozamPete

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#17
And you remembered to put the belt on first - Win Win. Looks good.
 
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