Cincinnati #2 universal head: terrible surface finish after dis/reassembly of spindle

Hello friends,

I posted this in the machine reconditioning forum and was suggested to post it here. So here goes: I have a new-to-me 1938 Cincinnati 2MH with the universal/toolmaker's overarm.



I had to disassemble and reassemble the internals of the overarm, which took forever with shimming the bevel gears for backlash and wear pattern. But everything seems pretty good now, the machine works and cuts nicely. However, the surface finish is abysmal. I realize the machine likely has lots of wear so it's possible I'm just asking for too much here, but I figured I'd see if there's anything I can do. What I'm most concerned about is that there is a collar at the top of the vertical spindle that seems to allow you to preload the bearings. If I crank down on it a bit, the spindle is resistant to turning and stops immediately when power is removed, for example. Too loose, and I can move the spindle up and down slightly.

I'm guessing there is some procedure to setting the correct amount of preload, however after weeks of searching I'm not able to come up with any sort of manual for this. Anyone have any tips or pointers?

Also, as I was typing this, I realized that the main bearing around the spindle might just be trashed. I went over to the machine and the spindle does have the tiniest bit of movement side-to-side. I've got a long-reach facemill arbor on it right now so there's plenty of leverage to produce a little movement, by hand. Guessing this might be a more obvious solution than I originally realized?

Dope

Update: I started messing with the machine a bit. I turned the large nut on top of the spindle 1/8 turn at a time and examined the effects. The surface finish cleaned up quite a bit, and I was able to take increasingly heavier and heavier cuts as I tightened the nut. I was using a 4" facemill and was getting chatter at .050" DOC (and a terrible surface finish at only .020" even), and by the end I was taking .175" cuts with no chatter. Unfortunately couldn't go beyond that, I was maxing out the motor (1HP on a static phase converter so roughly .67HP). Surface finish always has a tiny bit of chatter in it when focusing a bright LED light right on it, but I suspect the bearings are a bit trashed (they are a bit crunchy and loud). I have two sets of bearings for this machine so I swapped them out and it helped but only so much. Expecting much out of 80 year old bearings is probably a bit excessive.

Anyway, tightening the nut definitely increased the drag on the entire gear train but I can still turn the motor over easily by hand so I'm not super concerned. Will have to see if anything's heating up with prolonged usage. No idea how loud a machine like this should be in the first place, this is my first experience with anything but a bridgeport (which is very quiet).

Current surface finish on some smeary mild steel:

Basic rule of thumb: Heavy cuts tighter bearings, light high speed cuts, looser bearings... Use the proper lubrication and I know my Kearney and Trecker heads will run warm after a time....Cheers and Merry Christmas; Ramsay 1

Not at all the same over all but this at least may be interesting

I'll suppose you know BOTH the vertical and horizontal "shafts" have to be in the right place just to suit the spiral bevel gears - which are very fussy about mating up with each other

johnoder said:

Not at all the same over all but this at least may be interesting

I'll suppose you know BOTH the vertical and horizontal "shafts" have to be in the right place just to suit the spiral bevel gears - which are very fussy about mating up with each other

View attachment 308673View attachment 308674View attachment 308675View attachment 308676

Click to expand...

Yup! I've spent weeks dis-assembling and re-assembling the machine over and over, making custom shims, painting the gears to check wear pattern, measuring backlash etc etc etc etc etc etc etc.

Dope

Hopefully this helps