On the road to setting up for making clock gears I CNC enabled my bench-top mini-mill. The idea of machining in G-Code motived me to add stepper motors to the X, Y and Z axis of the mill and then later to a rotary table. The entire system is run from the open-source EMC2 program. www.linuxcnc.org
This set up below allows for the rotary A axis to rotate the plastic gear blank into position and then a cutter to be depthed via the y axis into the blank. This project is a 90 tooth spur gear that is first gashed every 4 degrees with a 1/2 inch 45 degree dovetail cutter (first video)
The actual teeth are "hobbed" by a 10 tpi ACME thread tap that the blank is pushed against. The pre-gashing of the 90 teeth ensures that the correctly sized blank properly engages the hobb as it cuts. The jacobs chuck on the rotary table is loosened so the blank will rotate and advance properly as the hobb cuts.
