My machine looses steps. When it does the motor makes a strange noise, almost a grinding sound. It doesn't happen all the time and it seems to be mostly the Z axis althouh sometimes X does it also.
I am using a hobbyCNC kit with the 305 ounce motors. I have it set for 1/4 steps. I have tried lots of motor tuning changes - mostly acceleration, and reduced the speed.
What might this be?