Help with planetary gear set

[Dimension_360]

Fair enough! Can’t wait to see them on the store!

[Ethan5956F]

@Dimension_360 can u ask for helical gears, metal bevel gears, ring gears, ball bearings, the 48t and 72t gears sold in claw kit to be sold separately (and with a ls/hs version), and some kind of new squishy plastic material that we would be able to custom shape and use to make a strain wave (a timing belt version) with? (last one can be achieved by making some elastomers legal and expanding on the custom plastic size limit, or allowing VRC the ability to 3D print, but a vex play-doh type product would be cool too ig)

thank

[Kyle1]

@weilin

This is not how it supposed to work. The direction of rotation for the 36t gears needs to be opposite, and you have them rotating in the same direction.

You will need an even number of 12t gears between 36ts, like this:

This touches on why the gearset doesn’t work, but isn’t true. Right now, disregarding friction and if you have the correct gears dead, the carrier is completely independent from the suns. Imagine holding both suns still, you’ll be able to roll the planetaries without fighting an input, and if the planetary is an output to find the gear ratio you have to divide by 0.

Now, there are two ways to solve this:

1. Make the gear ratio between the suns negative, as weilin said.
2. Keep the gear ratio ratio positive, but with a magnitude different than 1.

For your application (a variable mechanical advantage drive), you’ll want to have magnitude different than 1 regardless (which you can do with a negative ratio as well), or have a different input rpms. Otherwise one of your full power outputs would result in 0 rpm, rather than your ideal pushing rpm.

I personally would advocate for positive ratio, as it requires the least amount of gears, while a negative 1:1 ratio requires a custom carrier hole (and pinions meshing), and a negative off 1 ratio requires 3 pinions meshing - though if you really need the 60 tooth gear profile a 36 tooth planetary doesn’t work.

Here’s the clearest picture of my favored gearset. This current application is continuous power sharing, but its what I used for the multispeed drive designs too.

[9935E]

Thanks for the help once I can get the parts I’ll attempt to make it. I figured out that the carrier did nothing but I didn’t know why or how to fix it.

[Dimension_360]

In response to @Ethan5956F, as I am the *cough *cough humble *cough *cough servant of the people now (/s) can you pass on that we want these things @DRow? Thanks!

@Ethan5956F

helical gears, metal bevel gears, ring gears, ball bearings, the 48t and 72t gears sold in claw kit to be sold separately (and with a ls/hs version), and some kind of new squishy plastic material that we would be able to custom shape and use to make a strain wave (a timing belt version) with? (last one can be achieved by making some elastomers legal and expanding on the custom plastic size limit, or allowing VRC the ability to 3D print, but a vex play-doh type product would be cool too ig)

[Noah10851B]

While you are at it asking for V5 parts, how about an IQ part:

A motor encoder for IQ. It would be really convenient to have when your gears slip and throw off your autonomous. I know this would probably be much harder to develop than just VRC pieces, but if you do decide to make it, I think many people in the IQ community would really appreciate it.

[Dimension_360]

Sorry. I don’t do VIQ. lol.

You heard the man DRow!

@Noah10851B

A motor encoder for IQ. It would be really convenient to have when your gears slip and throw off your autonomous. I know this would probably be much harder to develop than just VRC pieces, but if you do decide to make it, I think many people in the IQ community would really appreciate it.

[DRow]

I posted this in another thread, but just wanted to close the loop here as well. The 12-pack of 12T Metal Gears (276-7368) is now available here: Gears - VEX Robotics