There are at least three possible causes for this unexpected
dropping in the Z axis. The first is a problem with the program.
Since you’ve got two of these machines, try running the same program
on the other machine. If it cuts normally, then that’s not the issue.
If it doesn’t, look carefully at the program parameters to see what
might be misdirecting the Z axis.
The second possibility is a mechanical problem. Look at the driving
mechanism for the Z axis and inspect it carefully. Slippage can be
caused by a loose pulley or screw in the driving mechanism, or an
insecure attachment to the motor.
The third possibility is an electronic failure. You probably won’t
be able to fix that without expert help, so give Roland tech support
a call, once you’ve eliminated program and mechanical issues as