Been using Mach 3 for about 2 years and have two different cnc routers.  Recently the z axis on the one router will begin cutting correctly then when it moves up and goes to another part of program it stays up in the air and cuts nothing.  Never returns back to the original z zero position.  I've tried everything I can think of: reinstall, motor tuning. checked servo's, driver test.  It keeps happening; even tired different programs (that I've run before) and nothing.

HELP!!!

Justin

It's probably a mechanical issue. Make sure nothings binding, no set screws are loose. Does it need lubrication?

You say you checked servo's? If it's servo powered, why aren't the servo's faulting when out of position? I'm guessing it's really steppers?

If it is servos then it may be the step signals are not getting through to the drives and thus it does not fault the drives. If you are using a breakout board it could be bad so if you have spare outputs swap the wires onto them and try. Also possibly the pulse width may not be sufficient for your drives so maybe try a bit higher.
Hood

Thanks for all the great input.  Turned out to be that one of the bearing slides on the z axis was packed with sawdust and once I got it all cleaned up seems to be running fine again.

Thanks again for the help!!

Justin