Ok so after over a year of sitting idle I fired up my old Hurco KM-1 to work on a project.
Everything seemed ok to start with, but once in a while it would seem to lose it's position. I scrapped a couple of parts I was making and really couldn't find a reason why.
Well tonight it happened right before my eyes. The X shifted position to the + direction by approx .125" and the Z shifted in the - position (yikes!) by almost .200"!
It mainly seems to happen after the machine has moved to a different position during a rapid.
If I remember right I think these machines have optical encoders on them with hall effect sensors.
I'm going to pull the covers off the servo drives tomorrow night after I get off work and take a look see. Other than possibly blowing out any dust/debris out of the encoders and checking the wiring to make sure nothing is loose, is there anything else I should check? Any common problems with these encoders?
The servos definitely need to be tuned as they are slightly erratic and rough sounding at times - kinda like just a little tiny "hiccup" that really doesn't seem to do anything other than affect the surface finish a little bit. They seem to be that way especially on slow movement.
Oh, and on that note, I swear it seems like the erratic motion in the Y axis is affected by whether or not the coolant is turned on. Coolant on, servo seems smoother.
I don't think that the erratic movement has anything to do with my current encoder problem since they've been doing that since I got the machine almost 3 years ago.
Then again, maybe it does. I'm still way new at this stuff, so maybe I am missing something. How do you tune the servos on these things anyway?