The New and Improved Split-Ring Compound Planetary

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.

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

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

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!

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! :)

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.

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

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

This is really cool and inspired me to make one of my own. I was able to make mine with a free wheeling sun gear on the output because I kept the module the same on the input and output. I made it with 50 teeth on the input ring, 20 on the input sun, and 51 on the output ring. This means the input plants were 15 teeth and the output planets were 16 teeth to keep them concentric with the input planets. A small correction to what you stated in the video is that for evenly spaced plants, (sun teeth + ring teeth)/(# planets) must be an integer, not (ring teeth)/(# planets) (you can also have an uneven planet spacing, in which case this does not have to be an integer). This is fortunate because it means that no matter what tooth offset you have between the ring gears, they will both satisfy this equation if one does. Adding some number of teeth t to the input ring means that the output sun will have (input sun - t) teeth. Then we have (s + r)/(# p) = (s-t+r+t)/(# p). t can be any number of teeth, so this would also work for your configuration of 50 on the input and 49 on the output. I found this document to be extremely helpful in learning about gears (page 61 has formulas for planetary gears) http://qtcgears.com/tools/catalogs/PDF_Q420/Tech.pdf

I can't get enough 3d printed gearboxes.

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

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.)

Thank you for posting this, I learned something about planetary gears from your very clear explanation, thank you.

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.

Congrats on 20k subs!

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!

Almost 20k subscribers! Well done!

youre going to go far in life dude. god bless you.

I would imagine the start of that failure was 2 of the planet gears getting out of even spacing. Likely that is what stalled the stepper motor. The nature of that mechanism is to forcing the planet gears off axis. The torsion takes them out of parallel. A carrier on both ends would help some, but if you take a look at automobile transmissions you see a single carrier that completely enclose the planet gears. This maintains the parallel of the gears. It may require too much space to be able to be used in your mechanism. You are a very bright young man. Likely you may have already figured it out for yourself.

Good build... I have to go back and watch what you had going on before because I don't want to say the obvious problem without seeing that you've already been working to tackle that.