I have a Komo VMC144XT machine center with a Fanuc 0M-C control. The counterbalance chain
recently broke, causing the head to drop rather violently before the Z-servo alarm was triggered
and the brake kicked in to prevent the head from dropping further. After replacing the chains,
the machine then would not move to the proper Z reference zero. It would reference to a position
about 8" below the usual Z-reference position. I used it for a few jobs this way, but had to do
manual tool changes because of the improper z-reference.
After perusing advice from several online forums, I moved the head up to Z+ over travel, shut
the machine off, then held "P + Cancel" while powering up the control and then referenced the
machine. This appeared to return the Z reference to its normal position.
However, now the tool change does not function correctly. The head drops slightly (about .05 to
.07 inches) when the tool change arm is directly under the spindle. Two alarms are generated:
1270 Extreme -Z overtravel and 1290 Extreme +Z overtravel.
I did notice that the Z reference position did not perfectly match the tool changer (was out
about 0.015"). I moved the homing position/reference dog and changed parameter 0510 to fine
adjust the Z reference position to suit the tool change arm. This made no difference as the head
still drops and generates the alarms when I try a tool change.
The tool change routine is in the ladder, not a macro. It seems as if perhaps there is a
variable that got screwed up when the chain broke and that this variable has not been reset.
Anyone have any ideas or suggestions on what might be wrong and how to fix it?