X axis cold start issue

[Daniel Boone]

I have a 1998 3016 with AC drives and the X axis motor is humming slightly, I dont know if this has something to do with the issue but I thought I should share this info. When I go to cold start I line up the marks and the x axis continues longer than the y and z , the when it comes to rest it is off about .250, So me being a smart guy I figured I would trick it and go .250 the other side of the line and it stayed on the other side of the line, so whenever I line it up with the mark it wont cold start back to that mark, If it not that big of a deal I can live with it,

This forum has been such a lifesaver for me Thanks to all that help!!

[scadvice]

...tried to re-set the CS positions? I would try that. Did this occur after the X axis repair work you just did on another post? That would be the first thing I would do. If the AC servo is reacting as a DC does... the whining should not be the cause, I believe.
Steve

[Daniel Boone]

I have tried resetting the cold start many times, the x axis motor whining was that way before the repair.

[scadvice]

...1) Your not re-setting it right ( that's unlikely) 2) the x axis coupling set screws are loose and the coupling is slipping.(possible) 3) the ball nut mount is loose and moving (a guess I've never had to remove one so I have no idea how they are secured) or loose motor mounts ( very... not likely)4) the encoder is the cause?? ( I have no clue but maybe its causing a miscount somehow. I'm surprised it doesn't error out)5) a parameter issue or adjustment??( now I'm drawing for straws)
Once you get it CS can you run a program?
My DC servo on the x axis is whining and I'm going to order a resolver for it, but it still seems to function otherwise. i.e. a program runs without problems and parts are in tol. no error messages. Maybe Neal has some idea's.
Steve

[Daniel Boone]

I have checked all the other items that you have listed all are fine, it will run a program fine, will pick up and set all work shifts fine, just wont cold start to the correct position, I have jogged it pass that section many times watching the display and its is not missing any pulses it counts them all, I have tried it in all increments.

[Neal]

Daniel--
Have you reset the ZERO OFFSET in the survey? It may have changed for some reason. The AC servo system uses an electronic adjustment to set the Cold Start position. The nDC system you can just rotate the resolver to accomplish that. NEVER attempt to rotate an Encoder on a AC motor. You'll destroy it.

Neal