I am (very slowly) building a guitar more or less from first principles. Worm gears are generally not back-drivable (aka self-locking), which is a good feature

I am (very slowly) building a guitar more or less from first principles. Worm gears are generally not back-drivable (aka self-locking), which is a good feature for a guitar tuner (you don't want the string to unwind itself), and it's why most guitar tuners are approximations of worm gears. One limitation of worm gears is if you want to make them compact for finger operation, I think you're basically stuck with the 90 degree input/output shaft arrangement. I'd like to experiment with different orientations so I went looking for other self-locking gear types, and found this page. It's definitely outside my wheelhouse but I thought it was really cool to learn that the locking feature can be achieved basically by varying the shape of the teeth.