Help diagnosing 6TB axis problem

[JohnF]

I have an OLD Kitaco Varient Turn lathe with a 6TB control. The X axis is acting up badly and I need to try to figure out what it is. I've been having a minor problem with finishes due to noise in the X axis for many months but it polishes out fine. The last couple days the noise has been worse and today it is so bad it's no longer acceptable.
It's a strong studdering only in the X axis. No alarms. I replaced the brushes today with no change. The X and Z motor are different so I can't swap them and the books I have aren't good enough to tell me which cables to swap to test switching the X/Z axis at the control box. I guess I could swap the physical drives but it looks to be a moderate pain.

Any suggestions?

JohnF
Phoenix

[underthetire]

Does it leave a bad finish turning or facing or both? First guess would be bad axis bearings, followed by a bad/shorted motor. Did you blow out the motor with air when you did the brushes?.

[Al_The_Man]

It could be a bad bearing in the ball nut, is this a slant bed? if so check the counter balance system, If possible, back the motor out so it is disconnected from the ball screw and see if the motor turns smoothly.
If no alarms, check the mechanical first.
Al.

[fanucman]

check the tacho generator.. and comm