This is a replacement for the gears in the MKII 5 Watt 3D printable Wind Turbine. It uses a 80mm GT2 (2mm) timing belt, an aluminium pulley with 28 teeth for the stepper motor shaft and an printed pulley with 75 teeth for the main shaft. The ratio is 75:28 = 2.68. Update 18-02-2017: Added a 74 teeth variant. with a ratio of 74:28 = 2.64. This one can be printed without a raft. The 75 teeth variant was little bit to tight with resulted in to much friction. The main reason for this replacement is that it reduces the gear noise. I printed this in ABS with the following settings: - Highest Quality - Layer Height: 0.06 mm - Print speed: 45 mm/s - Outer wall speed: 20 mm/s - Travel speed: 120 mm/s - Infill: 75% - Build Plate Adhesion Type: Raft (so you don't get an elephant feet on the teeth) The gear is based on this OpenScad design (http://www.thingiverse.com/thing:16627). I have included the scad file with the parameters I used.