I have my control box wired up in simplest form with the following components:

Keling 72VDC 20A toroid supply, both 10A outputs wired in parallel to
Gecko G203V stepper drivers to
Original Sigma motors wired parallel
WJ200 2.2kW VFD with shielded cable to original 2HP motor
CNC4PC C50 BoB
Original small control box mounted on right side of mill.


The Y-axis runs up to 150 ipm, X and Z up to 130 ipm without stalling when I was first setting this up.
I set the limit to 100 ipm with acceleration of 6 ipss.

When running a part last night, Z stalled on a home move and then again when returning to zero. The stall happened near the end-points of the moves (cost a new 1/8" end mill and the part).

The machine has been completely dissasembled and cleaned, so there is no binding. I thought I was being conservative with the motor tuning, so I wonder why the motor stalled? Is that too fast for Z? After that, I made a test program to full sweep all three axis simultaneously back and fourth 20 times, and there was no stalls at 100 ipm. The gecko's were not showing the yellow full current delivery (they are unlimited).

I read that the original setup was 120 ipm, but not sure if that applied to Z as well. I also read here that someone had their Z acceleration up around 13 ipss, which seems really high. I think I will set my Z for 80 ipm and 4 ipss and see how it goes.


One other item to address is a noise issue tripping the limit or e-stop alarm. I was able to quell that by setting 300 us debounce. I was just thinking that the noise might be getting into the PC since I tossed it up on top of the control box, and the electrical and motor cables run right next to the parallel port. Otherwise I need to replace all my cabling with shielded cable, at least the limits and e-stop cables.

Oh, and one other question I had was motor holding torque. I think the Sigma motors are 1100 oz-in. I can turn them by hand without too much effort. I think that works out to just under 6 ft-lb? Also, the Gecko should reduce current after 1 min to lessen heating. Just want to check that it makes sense.

Thanks