I am very new to cnc, and have recently built a Phlatprinter MKII from phlatboyz.com I am using a Mechatronics bi polar 3 axis micro step motor driver, with 3 nema-23 stepper motors. The machine is all belt driven. The x axis is a large belt driven roller similar to that of a large format printer. Y and Z are on a gantry below the cutting surface, and the cutting bit protrudes from below. When I run a cut file X and Y do not finish where they start. Y drifts progressively farther and farther in the + direction, and Z does so as well. To help diagnose the problem I rewired coil 1 to coil 2, and coil 2 to coil 1 reversing the steppers, then in mach I reversed settings so everything ran in the right directions again. After reversing the steppers I still have the drift but in the opposite directions. The drift is very consistant. The same cut file ran over and over leaves the cutter the same distance off. I have tried lowering the feed rates and acceleration, with no changes in the drift.
Is it possible that one coil is working better than the other in the steppers? If I could set steps per unit in the + direction, and then in the - direction independantly couldn't I compensate for this drift?
Jeff