Hello,
I am working on a very large 3D printer using Mach3 and smoothstepper. The B axis is slaved to X and C axis slaved to Y. Because we see little unexplained waves on printed part surface, I designed a recorder with a microcontroller and interrupts to calculate the theoretical axes positions from the step/dir outputs of the smoothstepper. I record these positions every 2 milliseconds. So I just use the PC+smoothstepper+recorder, no noise, clean pulses.
During the tests, I expected the master and slave axes to receive the very same pulses, but to my surprise, there are errors. Attached is a graph of the master axis position (in Pulses) and the Positionning error (in Pulses) compared with its slave axis. The experience can be reproduced with the same behavior; Up to around 20 pulses difference ! This may sound low, but we have low step per unit (160 per mm). Our parts surface is textured with low amplitude sinewaves (around 0.2mm peak-peak, not due to mecanichal noise, as these waves have precise and reproducible positions), but still visually unpleasant..
Did anybody realize there was a master/slave difference, and how could this be improved ?
Pierre.