12 and 36 teeth gears

The purpose of modeling and printing these two gears is so they can be used as part of a contraption that opens a window shade. The 12 teeth gear directly attaches to a stepper motor. The 12 teeth gear meshes with the 36 gear very smoothly. I modeled a spool for string which is connected to the 36 teeth gear, so as the 12 teeth gear turns the larger 36 teeth gear, the string winds and unwinds from the spool which opens and closes the shade. (String connects to the shade's pulley)