Spur parametric gear rack (experimental) (Q52062)

Warning: not yet printed (and I don't have a printer yet!) OpenScad script to generate parametric gear racks. Only one important parameter. There are 4 required parameters: * module: the most import parameter of any gear. Two gears (or a gear and a rack) of the same module will mesh. Determines the tooth height and this value is the pitch circle diameter in mm. Common gear modules: http://www.beltingonline.com/gears-366/spur-gears-367/metric-0-5-to-8-mod-375/ * number of teeth: this parameter together with module determines the length of your rack. * width: the width of the rack in mm. * rack bottom height: the height of the rack below the teeth in mm. The pressure angle is 20 degrees. This is not configurable since normally all MOD gears have a pressure angle of 20 degrees. When you print this thing please give me feedback. Change log 2011-09-18: Cleanup unused code + echo length of gear rack + center object + appropriate rotation for printing + added bevel to top of teeth