This is the harmonic gearbox we sell as individuals or in a 6-pack to make the Sixi 3 robot arm. At ten minutes each, you can have your entire arm assembled and ready in under 2 hours.
I’m putting together a 2 stage 20:1 Cycloid Gearbox that’s designed in Fusion360 and 3D printed on a Prusa Mini. The motor is a NEMA17 with about 30Ncm torque. As I go I’m explaining some design features and areas to improve. I hope this is fun and educational for you. If you find this useful, please caress that like button and show it to a friend.
Here is the Thingiverse file.
I try to make these gearboxes because I have yet to find someone that can make the gearbox I want. If you are that someone, ping me.
Mad love for Levi Janssen’s video about cycloid design in Fusion360. I don’t remember who first suggested to me to use the mounting screws in this way, but to you I say thank you! Very interesting!
Gearboxes can turn a weak fast motor and you need
When you buy a Marginally Clever robot kit, you don’t just get an awesome robot. You push the boundaries of science and engineering by funding my research. It’s a bit like I’m trying to run a personal Skunkworks.
You’ve heard me talk often on this site about my desire to build robot arms for less and make them for everyone. I need a gearbox so I can build the arms with affordable 3d printer electronics and hardware. Gearboxes transform weak but fast motors into slow but strong motors. Not every gearbox is right for robots. A good candidate is a hypocycloid, cousin of the harmonic gearbox.
these video’s aren’t mine. They are here to illustrate the concept.
I spent $3000 on a prototype that doesn’t work. In spite of the incredible tolerances and the top quality machining, we couldn’t get the gearbox to run without binding or jamming. More on that at the link, as well as details on my progress with the robot arm.
On the bright side, I can share my progress and save each of you a small fortune. Plus I haven’t given up. At a recent Bring-a-hack dinner after the 2015 Bay Area Maker Faire I got a number of great tips and suggestions about how to try again. They ranged everywhere from “run a kickstarter to fund more development” to “add more lasers”.
Do you have any ideas why the gearbox doesn’t work? Have you tried to make a hypocycloid or a zero-backlash gearbox? Comment below.
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I love the idea of hypocycloid reduction drives, or cycloidal reducers, because of they symmetry, their simplicity, and their promise of inexpensively using speed to get more power.
Some links I found about hypocycloids include http://www.thingiverse.com/thing:3617 and http://www.zincland.com/hypocycloid/
I’ve rediscovered – and written about – why cycloidal reducers aren’t commonly available.
