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Need Crossfeed screw bearings and housing for Series 60/61 (1954) with Taper Attachment

nt1953

Hot Rolled
Joined
Sep 4, 2004
Location
Huntsville, Alabama
When I bought this lathe, the leadscrew bearings (Find # R20) were destroyed and the bearing housing (Find #s R22 and R23) was severely damaged. I have tried off the shelf bearings, and did my best to repair the housing, but nothing is keeping the crossslide from moving a few thousandths when making cuts. I really need a set of good bearings and a housing for a Series 60/61 with a taper attachment.
 
I tried 7001 bearings (30deg contact) without success, but it turns out that the original bearings New Departure 0L01 is a 15deg contact, so that makes them a 7001C bearing. I will try them and then tell you what I find. I would still like to get a bearing housing and used bearings.
 
I'm looking at parts pic, and i have questions. I'd really prefer to have hands and eyeballs on the pieces.

But in cases where we are controlling end thrust, or back and forth end play, I could typically measure the movement, then add a shim or spacer between the back side of bearing and the housing of the same dimension. And reduce end thrust to .001" or probably zero in this case.

If housing was wore, maybe touch off with a mill to square up the wore contact area.

This is just speculation without laying eyeballs on it, any possibility there ?
 
The housing was broken on the closed end where the seal is mounted. I bored it out and put in a new part to retain the bearings and mount a more conventional seal. To the best of my ability, I have made the parts fit so that there is no play in the set of four bearings within the housing. They are in fact compressed when I install the end cap.

So, I speculate that the movement I am getting is because of movement between the inner and outer races moving relative to each other. However, it could be something else in the Monarch setup. I just don't know and am attempting to eliminate possibilities.

It could also be my DRO fooling me because of an improper installation, but I don't think so. I have installed three DROs and have never had any problems at all.

I was not able to get 7001 bearings work. They clearly had too much internal movement (why??). I have also tried normal ball bearings rather than angular contact. They worked better than the 7001 but not good enough. So my next attempt will be 7001C bearings that I have on order.
 
The few thou's you see on dro, are you seeing any anomalies in the work being cut, or is it pretty straight ?

A check i might do, is set up a dial indicator to see if i see the same on it.

If cross slide is truly moving on a cut, and the bearings are not moving on thrust, i can think of two possibilities. One contact area of threads on cross feed screw to cf nut may be flexing a little if the sides of threads are not full contact.

The other could be contact surfaces of cross slide to carriage, and contact area of the gib for cross slide. It could be ever so slightly rocking or flexing under the load of taking a cut. Might need to put a straight edge on those parts to check, and a little hand scraping to move contact areas out for greater rigidity.
 
Yes, the work shows that the movement is real.

I think it is the bearings. I'll try 7001C bearings and see if it fixes the problem.

I have thought about the nut to screw interface, but I don't think that is the problem. I have used some pretty worn lathes without seeing that sort of problem.

If the bearings don't fix the problem, scraping is next on the list.
 
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Roger, good luck with it.

I've still got to sort my cross slide and gib out. I have taper attachment also, and our style cross slide is pretty long, making the gib pretty long.

Reminds me of a milling machine table and gib. When wore, you can adjust, but it'll have a slight arch on dove tail side. So even though gib is contacting dove tail, it contacts in the middle of mating surface, allowing right and left to slightly rock back and forth on gib.

On a mill, I'd grab one end of the table and pull with all my body weight to check for this, maybe with a dial indicator set up. Then push the table the opposite way.

Might be an easy quick check on your lathe with dro on. Stand on tail stock side, grab tool post with both hands and pull. Step around to head stock and repeat. See if dro numbers moved.
 
Just a thought on an experiment for the bearings too, if you were inclined.

Remove the four ball bearings. Make two solid bushings out of bearing bronze to replace ball bearings. You could cut a couple of oil passages on the thrust faces. Machine the lengths to leave maybe .0005" end thrust. It'd be real ridgid and spin nice.

If it tightened up your readings on cuts and dro youd have an answer.
 
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I have new bearings now. I asked Monarch what the preload or torque spec was on the nut that preloads the inner races of the crossfeed screw bearings, and they said that there was none, that the preload was built into the bearing???
Does anyone have any idea about the preload or torque spec?
 
In areas where I'm dealing with end thrust I really prefer to make my own judgement vs a torque spec anyway.

I'm trying to recall if theres a nut to control end thrust, or if the bearing retainer with shims maybe ? Regardless id get end thrust to zero and just go slightly tighter. While doing that, shock housing and mounting with a hammer occasionally, as it could ease, or straighten up bearings. In conjunction with that keep rotating by hand so that it feels right while spinning. Too tight feels too tight, and too loose will have added end thrust.

Its a very low speed for bearings, they'll never burn up. Too tight may be bindy, or stiff to turn. If way too tight, balls may leave divets in the races.

I had been thinking too, as another check if original problem persists, you could probably pull the two allen head bolts out for crossfeed dial, and just yank the whole dial off as an assembly. Stick something in the whole to butt up against CF screw and use a dial indicator to take a reading off that, while you push and pull on compound. With maybe another indicator on cross slide, to see which area is moving.
 








 
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