Re: Stepper Motors from old Laser Printers

try reducing feed rate and acceleration

#define DEFAULT_AXIS_STEPS_PER_UNIT {80,80,4000,500} // default steps per unit for Ultimaker
#define DEFAULT_MAX_FEEDRATE {300, 300, 5, 25} // (mm/sec)
#define DEFAULT_MAX_ACCELERATION {3000,3000,100,10000}