Roots Blower

A Roots Blower is an air pump with strangely shaped rotors. They are used in automotive superchargers and high-vacuum pumps, among other places.

See http://en.wikipedia.org/wiki/Roots_type_supercharger

This is a stand-alone Public Domain OpenSCAD file you can use to generate these mechanisms. This is intended more as an example of an interesting mechanism than as a useful pump.

The file uses code appropriated from
Leemon Baird's PublicDomainGearV1.1.scad
which can be found here:
http://www.thingiverse.com/thing:5505