There is no calibration. First, make sure the feed rate is set high enough (I usually set mine to 8000 mm/min) or it will move really slowly. For it to move 1 mm per increment you need to be in step mode. If I click the "STEP" button (bottom left button) until the display shows "1000", it moves 1 mm per increment, or as close to 1 mm as the stepper resolution allows. Pressing the "STEP" button until it shows "100" makes the machine move 0,1 mm per increment of the wheel. "10" moves the machine 0,01 mm per increment.

It's a wonderful pendant once you figure it out.