Simple Gear Example-Inkscape to Openscad

This example is based on the following resources:
http://blog.makezine.com/archive/2010/06/make-your-own-gears.htmlhttp://repraprip.blogspot.com/2011/05/inkscape-to-openscad-dxf-tutorial.htmlhttp://www.iheartrobotics.com/search/label/OpenSCAD

Gear basics
If you know any two things about gears—outer diameter and number of teeth—you can use some simple equations to find everything else you need to know, including the correct center distance between them.


Number of Teeth (N)
How many teeth are there in the gear
Pitch Diameter (D):
The circle on which two gears effectively mesh, about halfway through the tooth. The pitch diameters of two gears will be tangent when the centers are spaced correctly.
Diametral Pitch (P):
The number of teeth per inch of the circumference of the pitch diameter. Think of it as the density of teeth—the higher the number, the smaller and more closely spaced the teeth on a gear. Common diametral pitches for hobby-size p