Several years ago, I realized that I didn't understand gear geometry, so I pulled out my old edition of Shigley and made an add-in for SpaceClaim that could generate a few different kinds of gears with a few different options. Works okay in most cases, but I'm wondering how others do it. I'm aware of some professional tools, but are there other tricks? Involute curves in feature-based CAD sketches? What about bevel and hypoid gears, which don't lend themselves so easily to planar sketches?
I haven't used my generator for anything serious, but have had a bit of fun: