Public Domain Involute Parameterized Gears

This is a public domain parametric OpenSCAD script for generating involute spur gears, helical gears, partial gears, and racks. The file defines the module gear(), which makes ordinary gears, helical gears (twisted like a screw), and partial gears (a wedge rather than a full disk). It also defines the module rack(), which creates a bar with teeth that will mesh with the gears, so you can generate a rack and pinion set.

The SCAD file also includes an example gear train. If you use the View/Animate command in OpenSCAD, you can see the gears and rack mesh and rotate together. If you change the number of teeth, the animation still rotates correctly.

This is not as powerful as other gears on Thingiverse, but it's public domain, so you don't have to worry about issues like GPL vs. LGPL. There are lots of missing features. Perhaps someone could build on this to create a public domain gear script with all the bells and whistles.