I recently finished constructing a cnc with uses the hobby cnc 205oz motors and their pro chopper board. Using mach 3 and mastercam to program it. The machine with randomly freak out, jerking back and forth a short distance on one axs and not not moving correctly for a short time and then the program continues. It is very intermittent and this code has been verified by other machines and the mach 3 tool paths. I have a nice computer running it with a PCI parallel port card. XP Pro in Standard PC mode. Interesting to note I duabooted EMC2 and the test showed a latency value 100x more then recommended. Not really over that learning curve yet. My other concern is it might be noise. I connect the motors with cables, connect all the commons to the foil wire shield (in pictures). I did this to prevent noise but it may not be the correct way? The motors are running at 2.5a. Also the Z and Y axis wiring is ran together through a wire guide in close proximity for 4 ft+, noise an issue?
So I figure its either:
software parallel port problem
noise
Attached pictures, what do you guys think?