I have just built my second reprap mendel.
during the initial testing the motors made a high pitch noise and did not rotate.
I have tried different combos of motors and drivers which work fine on the first printer but not on this.
The only thing that has been successful is to drastically reduce the steps in the firmware for example the x axis all the way down to 10, then the steppers will turn and move the intended axis by roughly the desired amount.
This seems very unusual, the problem is not the motors or the pololu drivers as I have tested then on the other machine, the set up seems identical to my previous machine ??
any suggestions what may be going on.
cheers