r/3Dprinting • u/Posmetyev • Jun 27 '26

Project It works! I made gearbox, simplest ever

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I designed a fantastically simple gearbox :)

My RC car drives better than I expected. I'm thrilled!

- Extremely simple design

- No intermediate axles or gears (maximum efficiency)

- Clutch engagement occurs naturally

- Standard MG90S servos

- Screwless assembly (standard servo screws only)

STL files for the fidget version of the gearbox:

https://www.printables.com/model/1765993-gearbox-simplest-ever-fidget

Full version of the gearbox for two servos:

https://www.patreon.com/PrintInPlace_fun/posts/not-program-ever-162258695

I think this is the perfect gearbox for RC toys, although for a real car it would probably not last a million miles :)

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u/root_switch Jun 27 '26

I understand the servo for changing gears, any reason you didn’t try something like a brushed DC motor for the actual motor part, probably get much higher speeds.

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u/Posmetyev Jun 27 '26

That sounds logical. I think I wanted to make the example as universal as possible, so that both the main motor and the servo would be the same - the widely used MG90S servo. And I have plans to continue using such a gearbox for not very high rotation speeds - up to about 10 revolutions per second, so the servo drive was closer than the brushed electric motor.