The videos below show you the theory: the stepper drives a sun gear with two planet gears orbiting, each of which engages a fixed ring of 56 teeth, and an output ring of 58 teeth. Each revolution ...

N 2 = NUMBER OF TEETH IN DRIVEN INTERNAL GEAR N 3 = NUMBER OF TEETH IN PINION MESHING WITH N 1 N 4 = NUMBER OF TEETH IN PINION MESHING WITH N 2 n = NUMBER OF REVOLUTIONS PER MINUTE OF DRIVING SHAFT n' ...