Fast Parametric Involute Spur Gears

Parametric spur gears (and rack) library that uses OpenSCAD list comprehension to build the polygons resulting in much faster compile and render.

The library includes functions for determining the pitch radius for your gears to allow the gears to be placed within your design such that they mesh properly (see the gear test example).

The library is as simple as possible and producing the 2D templates of the gears/racks allowing you full flexibility on how they are used.

Update 4 Apr 2017: fix error in dedendum calculation (thanks JPeterG)