Generate DXFs of hypocycloid cams for cycloid drives

Pin circle diameter
Pin diameter
drive shaft diameter
Cam center diameter
Usually pin diameter/2
Pressure angle limit
Offset in pressure angle
# teeth in cam
line segments in drawing

Max angle
Min angle
Max radius
Min radius
pin radius
pin distance


Does not currently do ANY checking for sane input values and it is possible to create un-machinable cams, use at your own risk


  1. Eccentricity should not be more than the roller radius
  2. Has not been tested with negative values, may have interesting results :)

DXF file


Copyright: 2011, Dan Royer

Version: v1, 2011-11-18

License: GPL

Original Python script by Alex Lait (

See Also

Formulas to describe a hypocycloid cam

Insperational thread on CNCzone

Formulas for calculating the pressure angle and finding the limit circles

Documenting and updating the sdxf library

DXF R12 file format