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

by Gear_Down_For_What Jan 22, 2017
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What would be the printing configuration for this design?
.2 x 25%
.2 x 100%
.4 x 25%
.4 x 100%

And what material do you recommend?

Hi, the model in file "Nema17 Mount Update3" has a small hole at the edge (see photo attached). What's its purpose?

Thanks for your work!

EDIT: Sorry, I watched the video now. I understood. Thanks.

Ciao, Very good project.
I print the gear whit a Creality Ender 3 using PLA+ at the temp of 210, perfect.
I use your gear in my Robot Arm (I intent to design a simply Robot ARM printable in small time and small pieces). I print and adapt your "Planetary Gear" also in a small version and it work very well.
Thanks for sharing your project in Fusion ( I modify your cover for use whit NEMA 23 in my robot arm). I post some photos.
When I finish my project I share it and I include your reference in the project.
Grazie mille!!!

Hi, great job! Some questions. What settings did you use to print the Nema 17 Mount? In your opinion it is possible to print it not inclined? Normally I use PETG but with the supports I do not get positive results. Greetings

Just watched your latest videos thats great what you do! Archimedes would definitely proud of you man :) Theres a bunch of nema models and I'm trying to pick a nema 17 motor that will bring at least 121.2 N.cm of holding torque with your planetary gears.
Thats for robotic arm (https://hackaday.io/project/26341-building-and-improving-the-thor-robot-arm#menu-description)
Can you suggest me the right nema 17 model or how to estimate holding torque? thanks!

does it matter how the drive-37-1 is oriented. i see on the picture that the D-shape is going with the flat side at left ( in direction of the arrow down arrow ) would it damage gears if not put exsactly like that ?

Hey! ;)
Great gears! I design my robot to works with it and it's doing very well.
You can check it here:

Bastion Inspired Robotic Arm
by chaczyk

I’m very ignorant when it comes to gear boxes, but is there any reason why I wouldn’t be able to use this as an increaser? I need a 50ish:1 increase for a small generator project. The input to the gear box would be ~60rpm for a speed at the output of ~3000rpm.

Thanks for posting this. Keep up the great work

Yes there is a reason, it won’t work. Low efficiency causes it to require a higher torque to backdrive than the teeth can handle.

hi great work,

when importing drive 37-1.stl to tinkercad it mess up the 3d files. what software did you create them in because my axis on my stepper is 6mm and yours seems like 5 mm or something.

Fusion 360, and nema 17 motors have a 5mm shaft with a .5mm flat. The gears with the larger hole are not intended to engage the shaft.

Thanks for this thing!
You write that the gear of this is 37.1 (or 49.3), but with the formula you posted under this thing (in the comments): https://www.thingiverse.com/thing:2220506 (FinalRatio = 1 / ((((TR2 -((TR1/TP1) TP2))/TR2) (TS1/(TR1+TS1)))) ) it calculates to 38 (or 50.4). What is correct?

1379:1 Compound Planetary Gearbox

It’s most likely that the equation is correct, as I calculated the ratio for this before the days of having a math equation for it, I just check it by turning it. I’ll look it over

Thank you for sharing this! Great job!! I would like to down scale that model by a factor of 2.5. Would you supply me with
the dimensions of your model?

Hi, I'm trying to print and build this gearbox, but the issue I'm having is that the ring gear gaps seem to be stretched apart too far when the planet gears pass over them. This causes the turning of the sun gear to be jumpy. I printed the files using the exact wall thickness and infill settings you mention at the beginning of the accompanying youtube video. Any ideas what I could do to fix this?

how do you figure it is a harmonics gear? there is no flexible gear!

I didn't know what else to call it at the time

i understand now . thx for the clarification.

This is a cool idea! I tried the wave generator style one already, but I don't care for the idea of having to use tons of skateboard bearings to form the ellipse. This really limits the size of the system. This sort of things seems to be a lot simpler. I'll give it a shot and let you know how it goes!

Hey thanks for the kind words. I'm going to try to do another video tonight explaining assembly better

Hey So i just printed your driven 37-1 gear and its sorta tight on my 5mm shaft stepper motor with a D shaft, maybe my printers over extruding a bit... what module and helical angle did you use to design the gears? I'll just make another one if you don't want to re-upload it.

On second thought. The gear box has a little slop. For a temporary solution try scaling that gear up my .003 or .006 in the x and y direction

I honestly can't remember but it's gonna be hard to replicate cause its scaled by a factor of .4 I'll see if I can figure it out for you.

I had the same issue and I couldn't get it on the first time but now it's really loose, I'll maby add .05mm tolerance to that part. I'll try get that done tonight after I get the video uploaded.

So I sort of figure it out based on one of the gears I printed, in 1 to 1 scale your at a 8mm face width on your gears, something like a module 1.2 in for your tooth size, and something like a 20 degree helix angle. If you're interested, I've had luck printing all the way down to .6 module gears, though it probably should be done with a .3mm nozzle, that would help reduce the size of this gear box significantly. i use module 1 if size doesn't matter and .8 usually for things to still work on my system. I might try redesigning one of these to be a bit smaller for a small robotic arm i'm working on. So far the gears have come out awesome though!


Yeah I think it would be useful to downsize this gearbox i think it's bigger than it needs to be for sure!

Comments deleted.

It's designed to mount to a nema 17 stepper motor. I will test it tonight if I get my motors in the mail. I'll post pictures too

Love it.
Any chance of posting the mount for the opposite side to the stepper motor?
Final request - for anyone wishing to integrate this into a larger project, can you provide the source or alternatively the design requirements for the mounts?

I misread your first post, yes I will post the enclosure for the other side as soon as I can get fusion 360 to behave for long enough to make it fit correctly.