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Thread: Rough Cross Feed
03-14-2017, 01:45 PM #1
Rough Cross Feed
I've got a problem with my recently acquired South Bend 16" lathe (circa 1958~1962) and am looking for some advice. BTW, this is a home shop machine and I'm a noob!
The cross feed is quite rough when advancing across the table but very smooth when returning. Facing a part is not affected by the rough cross feed though. It just feels rough and makes me think there is something damaged.
My 1st guess was the cross feed nut. I pulled the cover, gib & the compound rest assembly. The screw & cross feed nut have no visible scoring at all. The nut is securely attached to the slide. Backlash is in the order of 0.030 to 0.040, so yes there is obviously some wear. The gib had some nasty looking spots so it was cleaned, deburred & lubed. The ways look to be in good shape, with minimal scoring, but admittedly I didn't measure them. Retracting does get tighter as the slide is retracted all the way, but adequate in the working portion of the ways. I did not pull the slide apart further to examine the bushing/bearing for the screw, but that is my next guess as the likely culprit.
Anyone have any experience with something like this? Is there a thrust bearing on the screw, or just a bushing?
03-14-2017, 02:18 PM #2
Sounds like the small thrust bearing between the bushing and gear on the screw is shot. You can basically screw the entire cross feed assembly out of the front of the saddle and work with it on the bench. There should be an octagonal feature at the base of the bushing you can get a wrench on.
03-15-2017, 07:12 AM #3
Thank you for the info kitno455. You are correct, I disassembled the cross feed last night and the thrust washer between the ball bearing & the screw was badly scored. The ball bearing looks fine though. I flipped the washer over and reassembled. Problem solved!