Hi: I have a VMC that had a Fanuc 6MB controller. I've converted it to Linux CNC but kept the AC Spindle servo unit and I'm having a problem.
The systems works great most of the time. The spindle works as commanded, takes speed commands, is stopped when it thinks it's stopped, does orient, etc just as it should. However, sometimes when the unit comes on it spins backwards slowly. When this happens, a speed command works but not really.
The machine reports it's come up to speed (and the command voltage is correct) but the spindle spins really slowly. For example, it I send an M3 S5000 command, it only spins a few hundred RPM but thinks it's come up to speed. When I send an S0 command, it thinks it stopped but it's still spinning slowly. Orient works just fine, holds the position as stopped but as soon as I release orient, it keeps spinning.
Sometimes it works great. Sometimes it comes up on this mode. No alarms in either case.
What do you all think? Any ideas?
It's a "Model 3" AC Spindle Servo. A06B-60AA-H007.
Thanks; Erik