I thought some of you may be interested in this. I modified my milling machine to do gear hobbing. The goal is to turn the gear blank by exactly 1 tooth per revolution of the mill. To achieve this, I use a motor, shaft encoders on the mill motor and the gear blank motor, and an arduino running PID controller software to keep them exactly in sync. I also needed to tilt the mill head by the angle of the hob teeth, which I did with a thick shim. Here's a picture of the hob cutting a plastic gear (just for a test). This was before I hardened the hob so I wanted to cut something soft. And here are some gears I've made. Some spur gears and a worm gear (the worm was made on the lathe of course). I also used this to make the gears in my Webster engine. Cheers, Ross.