How Planetary Gears Work | 3D Printed Planetary Gearbox Design and Test

Measuring tools used in the video (affiliate links):
Amazon:
AliExpress

Parts list (check website article for full list, affiliate links):

AliExpress:

In this video we will learn what is a planetary gear set and how it works, as well as explain how to design our own planetary gearbox and 3D print it so we can see it in real life and better understand how it works. At the end of the video, we will also do some backlash and torque tests to see how well it can perform being a 3D printed gearbox.

00:00 What is Planetary Gear Set?
03:37 Two-Stage Planetary Gearbox Design
06:56 Design Rules
08:38 Gears Module
09:15 Designing the Gearbox
12:45 3D Printing
13:25 Assembling
17:22 Backlash Test
19:22 Torque Test

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[MrAlex]

Thank you for not only providing the design for free, which I am most of the way through printing on a 1mm noz. but also for providing an article that I can read and follow instead of the video. I prefer it.

[jakabgipsz]

The only thing the world forgets is that it owes it all to a Hungarian engineer inventor called József Pigeon. He left Hungary for the World's Fair and stayed in America. He became a collaborator of Henry Ford. One of the Ford T. models received this kind of gearless drive. By gradually braking the outer ring with a lever-operated fairing, the car went faster and faster.

[NavySturmGewehr]

Unbelievably impressive. I've been looking up the math on planetary gear boxes and walking away frustrated. This video is in a class of its own. Sub'ed!

[ArnaudMEURET]

Very good coverage of a well-known design. Done better than most other channels. I bet this is an interim video before a bigger project is revealed! 😉

[LeesChannel]

One of the contributing factors to the low efficiency of the planetary gearbox is the helical gears. Helical gears, due to their nature, cause axial load. Straight cut gears would be more efficient, but less durable because only one tooth is engaged at a time. An interesting compromise would be herringbone/chevron/double helical gears, in which the axial force is the same on both sides of the gear. It still has the advantages of multiple tooth engagement, and quieter operation, but with a neutralized axial load.

[VasilyLementar]

It would be awesome to see how you design such complex assemblies in onshape or fusion360. Raw 10 hours video, preferably with comments :). I still have no idea how to design projects where parts interact with each other

[DanielBulyovcsity]

You could stick 3 of these together and use it as an astrotracker for star photography once you polar align it.

[VideoGems]

I've been trying to learn this for a year. Your video is the first on YouTube that's made sense. Thank you so much for including the equations

[rodriguezangel]

Awesome video! I think we’d all love a comparison video of this and a V2 design a bit more optimized for efficiency. I wonder how high you can get and how impactful different design changes can be.

[patrickmchargue]

Thank you. This was very easy to follow and explained the subject well. Good job! I appreciate the tests and measurements you did at the end. That's the best kind of science.

[lezsgkz]

great video! a comparison of harmonic vs cycloidal vs planetary gearbox, all 3d printed would be cool!

[NicksStuff]

This is the way to do it. Model your parts the size they should be and include the manufacturing tolerance in the slicer.

[antalz]

I think the tight running of the gearbox might be due to an inaccuracy in modelling the ring gear. When you do the boolean operation, the addendum of the original gear becomes the ring gear's dedendum, and the original gear's dedendum becomes the ring gear's addendum, and you don't mention in the video correcting for that. You usually have to because standard addendum is 1m, while dedendum is 1.25m. I think I'm also seeing that at 7:04, where the tips of the ring gear teeth stick all the way into the grooves of the planet gears. The grooves of the ring gear look good though so I'm not 100% sure. In my own tutorial I fix this by "press-pulling" the teeth of the original gear to make them longer, and then increasing the ID of the original gear, before performing the boolean operation.

[chucksmalfus]

Not sure what torque value for the stepper you used, but the advertised torque of a stepper is the holding torque not running torque, sorry if I missed you actually measuring the running torque of the motor.

[Leroys_Stuff]

Impressive gearbox there these are in everything they work so well

[fernandohood]

Well explained. If you could now apply this method to explaining a an automatic transmission that would be awesome.

[PhilemonObedObeng]

Precision is impressive, is it advisable to use it as a waist joint for a robot arm?

[duanejohnston]

Such a great video! My next 3D printed project!

[gearscodeandfire]

This was super helpful in a sea of planetary gearboxes

[erikev]

How can the ring gear teeth get correct geometry if they are constructed by subtraction from a regular gear? Does the tool not support a ring gear with correct tooth geometry?