This is a minimal library for the generation of cycloidical gears. Some demo functions are included. required: OpenSCAD version >= 2015.03 !! MOST CURRENT VERSION HERE: https://github.com/lsuess/scad-lib-cyclogearprofiles usage: ... use // include would execute the demo modules To get a crosssection of the desired gear invoke: cyclogearprofile(rtooth,nteeth,vpt,verbouse); parameters: rtooth ... radius of gear teeth nteeth ... number of gear teeth vtp ... optional parameter -- vertices per tooth -- if left 0 (this is default) OpenSCADs resolution parameters $fa $fs or $fn will be applied. verbouse ... optional parameter -- If this is set bigger than zero then info about that gear will be reported under the choosen number. To get a cross section of a rack invoke: cyclorackprofile(trackmin,rtooth,nteeth,teethshift0,vpt=0) trackmin ... thickness of rack at the thinnest points rtooth ... "radius" of gear teeth nteeth ... numbers of teeth of rack (smallest allowed unit is a quater of a full tooth cycle) teethshift0 ... at which quater to begin with the first tooth sensible are valued from the list: {-0.75,-0.5,0,+0.5,+0.75} all others have same effect vpt ...same as for cyclogearprofile There are two helper functions to align gears. One for normal meshing an one for the case that one gear has the teeth inside (a concave gear) such that both gears turn in the same direction. alpha2(n1,n2,alpha1,beta12) // for normal meshing alpha2inroll(n1,n2,alpha1,beta12) // for gears rolling inside concave gears parameters: _1 ... gear in origin; _2 ... meshed gear beta12 ... angle at which the meshed gear is located nX ... number of teeth of gear X alphaX ... rotation angle of gear X around its own origin If you want to make herringbone gears use this helper function. twistextrudegear(rtooth,nteeth,slant,nteethtwist) your_modified_cyclogearprofile(...); The generated extrusion height (for nteethtwist=1) can be obtained with this helper function: extrudeheight1tooth(r,n,slantangle) To twist over the angle of multiple teeth use nteethtwist > 1 & multiply nteethtwist to the return value of extrudeheight1tooth.