I have a 20th Century ballscrew 3/4" x 5TPI that i will be using for my z-axis. I took it to have the journals turned and when I go to pick up, I notice the nylon insert has popped out and bearings are visible (there is a nylon insert that threads onto each end of the ballscrew and into each end of the ballnut to keep the bearings from popping out). I think the machinist spun it on the lathe without taping the ball nut in place. ARGH!!! Anyways I was able to get the ball bearings back in the ball nut. When I spin the nut counterclockwise everything is fine, but when I spin it clock wise it binds and it looks like the bearings are pushing up against the nylon insert and trying to push it out. Unfortunately I do not know if all the bearings were intact??? There may be a few missing. Does this problem sound like bearings may be missing???? Any help would be greatly appreciated.

Thanks,
Chris

If it's an older screw, every other bearing will be a slightly different color and/or size...take a close look and stagger them if the look and/or measure differently, which they will. You should have the same number of each.

How many recirculation tubes/circuits does the nut have?

Sounds like a recirculation channel may be out of alignment - you have nothing to loose here - take it (the recirc tube(s)) off if you can and take a close look to make sure it's not damaged.

Sorry to be so short - got to run.

Scott

Thanks for the reply mxtras. I have attached a couple of pics in my original post to hopefully give a better idea of what i am dealing with. I think this ball nut has "internal returns". Does this sound correct??? If so is it possible that one of those could be out of alignment?? I guess i could take out all of the balls and check...argh......BTW the ball bearing are all .125 in size, no alternating sizes....I do not know how old this screw is. It was sliding real nice before....argh..... Take care....

The machinist should have remove the nut first before machining. It could have been slid off onto some threaded rod or even a wooden dowel.
It may be that there is some swarf in the returns. Since you have had it apart now, you could investigate. Take the balls aout and hit it with some compressed air. Wear eye protection and don't point it at anything. A towel wadded up may be your best target. You may get some pipe cleaners to feed in the returns to clean them up.
I have heard of stuffing these with oversize bearings for a greatly reduced backlash. If you think balls are awol from the assembly, this may be an option for you.

I would guess it's packed with garbage from the machining - just a guess. Carefully dismantle and clean - no tubes, probably a single return internal circuit like you said. I see a plug (?) on the smaller end of the nut - may be the transfer channel?

I think it will all make sense upon tear down.

Suggestion - use whatever grease the manufacturer suggests - probably a thin bodied lithium. To thick and it will foul things up - especially if it is a one circuit nut.

Scott

Oh - I would suggest that you take your time and remove all the balls before you hit it with air - you would not want to have to hunt around the shop for an errant ball.

Use solvent and patience, not force to loosen anything that's bound up. Hopefully you find something!

Just my thoughts.

Keep us posted!!

Scott

SO?? What did you end up with???

Scott