P.Harmonic Gear Reducer

thingiverse

Watch it go at: https://youtu.be/sdRGrTHq4hA This hybrid gear reducer is a unique fusion of planetary and harmonic drives. It begins with a conventional set of 5:1 planetary gears, featuring a ring gear with 96 teeth. However, I've extended the planets and sun gears and added an additional flexible gear with 93 teeth, effectively creating a harmonic drive. The overall reduction is 155:1. It's no surprise that the ingenious Emmett has also designed a hybrid planetary/harmonic drive - https://www.thingiverse.com/thing:219779 - but this one utilizes a significantly different structure. The flexible gear is coupled to the output ring with flexible fingers rather than a flexible cup, and the output ring is supported by a ball bearing using 6mm dia airsoft pellets as balls. I designed this gear reducer to mount on a standard NEMA 17 stepper motor, although you can demonstrate it by hand without a motor or the ball bearing. In fact, the latter two components are not necessary for the demonstration. Final note: This is primarily a demonstration gear reducer and not intended for prolonged use. I printed mine out of PLA, and after about 15 minutes of high-speed operation, the flexible gear cracked. Printing with other materials may result in a longer lifespan, but really, any 3D printed gears are not suitable for high speeds or extended usage.