9-pin sprocket for bicycle chain

thingiverse

To direct-drive a bicycle chain from a stepper motor on a Cupcake CNC, I tried different sprockets using Google Sketchup 8 and the DXF/STL export plugin. The 9_pin_stepper_sprocket_final.stl version seemed ideal. A raft helped maintain a flat print surface. After printing, insert the stepper motor shaft, level it, and hold until cool to ensure a snug fit and proper functionality.