The New and Improved Split-Ring Compound Planetary

In my last video I prototyped and tested the split-ring compound planetary gearset, a super high reduction ratio mechanism. In testing, it failed prematurely. This time, I improve upon the design to prevent the previously discovered failure mode in an attempt to increase the stall torque.

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[LeviJanssen]

I realized that my comments on the many suggestions made on the last video could come across as somewhat harsh. This was not my intention, and I intend to encourage discourse and community. I just found it funny how many people had the exact same suggestions. And my joking is often steeped in thick sarcasm, so I can see how it could be misconstrued.

[-NGC--]

The engineering process is a lot cooler when it’s someone else going through it

[CallanChristensen]

My favorite line: "I wanted to see some gears get turned into wheels..." I'm really enjoying seeing your design/test/improvement process, keep it up!

[jaustinpage]

Herringbone gears tend to make 3d printed gear teeth a lot stronger without significant drawbacks...

[flyingmexican]

The next short one could be a redesign of the gears as the standard spur gears don't have as much surface area as helical gears which should give a bit more strength. Other then that awesome to see you followed up on the original failure! :)

[madeintexasd]

I can't get enough 3d printed gearboxes.

[ddegn]

It turns out it is possible to have an idler sun gear on the top layer if you use the right combination of teeth.
If you haven't seen it yet, make sure to watch the video *"Split Ring Compound Planet Epicyclic Gear"* on David Hartkop's channel. I'll add a direct link as a separate reply in case it gets caught in a spam filter.

[justfddr]

You need a cage at the bottom of that planetary set as well. Might last better.

[ChmpgneRm]

I'm really curious to see how these gears would hold up if they were made of a stronger 3d printed material (e.g. Nylon, PEEK, Ultem, etc.)

[lordfly]

If you want to maintain ~172:1 and still have 5 planets, but also have an idler sun gear in the center, use the following:
Drive Sun - 22
Drive Planet - 18
Fixed Ring - 58
Idler Sun - 31
Output Planet - 24
Output Ring - 79
This will result in 172.36:1

Also, slight correction to your statement at 2:50 - The number of teeth in the ring gear PLUS THE NUMBER OF TEETH ON THE SUN GEAR must be divisible by the number of planets. Since you have 20 teeth in the sun, which is also divisible by 5, it just so happens that if your ring is also divisible by 5, so is the sum. And the problem with your idler sun not fitting at 3:30 is not an inherent property of the mechanism, it's just a result of the tooth counts you have used.

Excellent video, I hope to see more on this topic!

[FKnopsMckim]

Really great work! One thought that has sort-of been raised by others is to have an output bearing located on the gearbox output before the lever arm. That should remove most of the load perpendicular to the gearbox and hence the deflection and subsequent damage. Looking at all the BLDC gearboxes I've worked with, they all have a final bearing on the output shaft for this purpose.

[markjennings]

The addition of the carrier ring is a good solution - but it is a tension ring allowing one planet to move and pull all the others off centre with it. A compression ring would probably be more effective as this would close the gap between it and the outer ring. This introduces a friction element that could be minimized with grease or further reduced by introducing a ball race similar to my 'lazy susan' comment on your cycloidal video. The difference is subtle but would remove the twisting forces on the planet bearings that also failed.

[GadgetAddict]

It's a shame it's not back drivable. It would be nice to have a simple gravity generator like that.

[HK-ocpn]

Audio is much clearer than past videos, and your storytelling continues to be great

[mikeag]

"I set out to break something, and I broke something" off camera: "my foot... " 😖

[ZoeyR]

Looks good my only recommendations are put do the same on the other side and support them with bearings.

[andreaudio]

I wrote to makers muse, and I'll write the same to you...
Try use POM filament... It's freaking hard to print (wont stick, it'll warp A LOT) but damn... When you manage to print it... that's some GOOD gear material...

[Arekseon]

you should checkout recent Maker's Muse video where he is testing gears out of different filament for strength.

[monstercolorfunco]

The best of these use specific planetary mixes from a planetary gear sim that are coherent, a sun gear in the middle of both, and the modulus of both is changed so the planets align, so one planetary modulus is 1 and the other is 1.037 and so the centers of the the planetaries are aligned.

[OhHeyTrevorFlowers]

I love seeing your projects. Separately, it’s also fun to see your storytelling and video production improve with each post.