This video, via sonodrome, demonstrates how you can use a power drill to control your synthesizer:
This video is a quick test and proof of concept. The Idea is to use a continuous rotation potentiometer as an input connection for drills, in this case the drill is used to control the pitch of a square wave oscillator.
NOTE: I would not recommend you try this out! but If you do intend to try this yourself, please take great care, you could easily hurt yourself or damage your equipment. Also I’d highly recommend using goggles.
Sometimes there is no why, there is only do, or do not.