Compound Planetary Gear Box (37:1 or 49.3:1) NEMA 17, No Hardware.

thingiverse

I firmly believe that this is the best 3D printable gear configuration available. It boasts incredibly low friction and does not require any hardware or bearings to operate at speeds over 1000 RPM for an extended period. With some of my newer remixes of this design, it's possible to mount this type of gearbox to a NEMA 17 Motor, and by adding more modules and interconnecting every other sun gear, the backlash can be reduced nearly to zero. I have created many new, improved gearboxes (with enormous gear ratios) similar to this one! Check out my other "Things" for updates. Video of gearbox driving knee joint on InMoov legs: https://m.youtube.com/watch?v=Ah7cCeW9HrY Please check out my YouTube video below! This design features two distinct gear ratios, depending on which sun gear is driven. The large ring gears have a different number of teeth but the same outer diameter and notches, allowing you to choose which way to insert it into the capsule. This is how the gear ratio is changed, along with using different sun gears. Please note that you don't need the other sun gear or its mounts just to try it, but it won't work as well without them. Also, make sure not to couple the two sun gears together - it won't function properly. These parts have all been printed and proven to fit. I ran this on with a drill at full speed for 3 minutes, and the gearbox held up very well. I suspect that with a few dabs of grease, this gearbox could handle an input speed of 1700 RPM for hours. PRINT INSTRUCTIONS: You'll need 3 or 4 planet gears (the long double gears), with 4 being the best choice. You'll also need a large carrier ring and a small carrier ring. For the 37:1 gear ratio setup, you'll need the "Drive Sun 37:1" and the "Driven Sun 37:1". For the 49.something:1 gear ratio setup, you'll need the "Drive Sun 51:1" and the "Driven Sun 51:1". If you plan to use it for anything more than a demonstration, you'll also want to print the NEMA 17 mount and the end cap that mates with it. PLANET GEAR PHASING INSTRUCTIONS - IMPORTANT! The planet gears are technically dual gears. They're two gears attached together, each with a different number of teeth. After studying this, I realized that they must be assembled so that they're "relative" to each other. There's a picture in the files to help you do this properly. I've included the Fusion 360 project files, and if you want, you can modify this and stack the planetary gears to give this gearbox 4 or 8 modules for use in high-torque applications. I would also suggest interconnecting every other sun gear to do this. Thanks for checking out this thing! Update: I figured out how to calculate the gear ratios on these gearboxes. So, I wrote an Arduino program to spit out the best teeth combinations. I'm currently working on making one with a gear ratio of 1,400:1 and the largest number of teeth being a 53-tooth ring gear. I'll include this program with my gearboxes. For more cool projects and upgrades, don't forget to follow me on Thingiverse and subscribe to my YouTube channel, Gear Down For What?