Howdy, I have a G540 running 3 425oz nema 23 steppers at 3A each, with a 48V 7.3A power supply..

I just finished converting one of my machines (Rong Fu 40 milling machine) with ballscrews (direct drive, 5mm pitch screws) and I was surprised that I can easily move X or Y at 120IPM. It will actually go a bit faster, 150ipm seemed ok, but 180 would stall randomly, so I left it at 120. Like I said, I can move X or Y independently at 120IPM to the limits of each axis with no trouble. But the instant I try to move BOTH at the same time, one will stall and the other will slowly try to keep moving..

I lowered the rapids to 100IPM and set the acceleration way down, but it didn't help. Seems like the fastest I can move both X and Y is around 60IPM.

I'm wondering if anyone has any ideas of what it could be. The power supply should be enough to provide the current required by both steppers, shouldn't it?

One other thing I just thought about is Mach3's kernel speed - right now I have it set to 45kHz. Is the pulse speed per axis though? My settings are at 10160 pulses per inch on X/Y, at 120IPM that's 40360 pulses per second. To have 2 motors moving at that speed, would I need 80000 pulses, or will Mach3 send the command for each axis in the same pulse? I'm assuming it's the later, with it being a "parallel" port, but who knows..

Any thoughts would be greatly appreciated!