I recently purchased a ZX-45 conversion (Actually ZX-7045) and the Z axis is for crap and I'm wondering how to solve the problem. First what is wrong... moving the Z always causes the servo driver to fault, oh it moves but it starts out smooth (short period of time - a second or two) and when ka-chunks its way along faulting with each ka-chunk. It does this in both directions.

Servo driver is Gecko G-320, Motor is Reliance E660 1/4 HP (660 oz-in), encoder is US digital 250 PPR, Servo voltage is 60 VDC, Servo sprocket to lead screw sprocket is 1:2 - 1/2" timing belt, lead screw appears to be the original from the manual machine, Software is Mach3 with 33,000 pulse rate.

I'm making the assumption that since it starts out ok, but faults when the speed picks up that it can not handle the pulse rate (acceleration). Originally the encoder was on the lead screw shaft, but it was also previously on the motor since a housing is still attached to the bottom the motor. I moved the encoder to the motor and I still get the problem and it has improved, but it still isn't 'right'. I can not find enough information on the motor to calculate what the encoder PPR should be. I can get it to move without faulting using a very very low speed and with that the ka-chunks turn into hick-ups.

When I hand turn the Z lead screw by hand it is smooth in both directions, but require much more force to raise the head (not unexpected - gravity you know), I'm wondering if the motor is undersized, if the sprocket ratio is too small, should I check the servo and add a stepper, etc.

Any suggestions from working ZX-45 conversions?