When I was making gears, a pen and paper, and a $11 Casio science calculator were the main things I used to figure out angles, etc. It had a nice DMS (Degree Mi

When I was making gears, a pen and paper, and a $11 Casio science calculator were the main things I used to figure out angles, etc. It had a nice DMS (Degree Minute Second) conversion mode. You write down your calculations and keep them with the work, as you're working on multiple jobs at the same time, and it helps keep things straight. There's grease and oil everywhere, stuff tends to disappear or get forgotten, so a low budget knowledge base works best. It's amazing how much stuff you can get done with such a cheap calculator.