pic: CGX-108 front

[s_forbes]

Awesome to see a working prototype! Got any pictures of the inside?

For the wobble plates, I don't expect the plastic to hold up very long at all, but if you have the ability to cut plastic ones easily you may be able to iterate with them until the fit is just right, so you know what dimensions to use for the aluminum/steel versions. Also, will the metal versions be laser cut? I'd be curious if there is any kerf angle as a result of lasercutting that might affect the interface to the rollers. With such tiny pins, the tolerances on all of the parts will probably have a big affect on the performance.

I'm really interested to see how the final one performs! Maybe you could set up a simple bench test apparatus (turn a pulley to wind up a weight, for instance) to test it under different loads. Data is useful!

[asid61]

Originally Posted by s_forbes

Awesome to see a working prototype! Got any pictures of the inside?

For the wobble plates, I don't expect the plastic to hold up very long at all, but if you have the ability to cut plastic ones easily you may be able to iterate with them until the fit is just right, so you know what dimensions to use for the aluminum/steel versions. Also, will the metal versions be laser cut? I'd be curious if there is any kerf angle as a result of lasercutting that might affect the interface to the rollers. With such tiny pins, the tolerances on all of the parts will probably have a big affect on the performance.

I'm really interested to see how the final one performs! Maybe you could set up a simple bench test apparatus (turn a pulley to wind up a weight, for instance) to test it under different loads. Data is useful!

Pics of the inside have been uploaded to CD. If you want more specific pics I can get them.
The plastic ones are already wearing out a ton, but I do need to use them for iteration. The lasercutting seems to be accurate to +/-0.001" with almost 0 kerf angle, so I get realistic predictions of what metal ones will do from it.
The metal versions will be CNC'd for now, and wire EDM'd hopefully for the final version.

[marshall]

Originally Posted by asid61

Pics of the inside have been uploaded to CD. If you want more specific pics I can get them.
The plastic ones are already wearing out a ton, but I do need to use them for iteration. The lasercutting seems to be accurate to +/-0.001" with almost 0 kerf angle, so I get realistic predictions of what metal ones will do from it.
The metal versions will be CNC'd for now, and wire EDM'd hopefully for the final version.

This is really cool. How are the gearboxes holding up? Any interesting failure modes observed so far?

[nuclearnerd]

This is a really cool project, and I'm anxious to see the final result commercially available. Although I would be even more excited if you could make your own final stage as well. The Vex final stage has really insufficient mounting strength at high ratios. Two #10 bolts isn't enough to hold the reaction torque (above 100:1 on a bag motor) in our experience.

[Chris Endres]

Nice! Ever since you posted the CAD a few months ago, I was eager to see it come to life.

Good luck on the final iteration! Hopefully this will be something VEXPro will look into in the future, it really is a nice way to get a compact and high reduction stage for Versa Planetaries.

[cbale2000]

While I'm still of the opinion that cycloidal gearboxs are magic, the thought of a 20:1 or higher reduction with limited or zero backdrive in a VersaPlanetary form factor is VERY appealing to me. It could also be a way more flexible and compact solution for applications that many teams currently use worm gearboxes for.

[asid61]

Originally Posted by marshall

This is really cool. How are the gearboxes holding up? Any interesting failure modes observed so far?

Thanks! The "good" failure mode is just a ratcheting due to the plastic teeth skipping, and the gearbox still runs afterwards. The more common "bad" failure mode is when the plastic gears go skew on the shaft, locking up the gearbox. Using metal hubs or bearings should fix these issues. I would not use the gearboxes on a robot right now, as the tolerances are all over the place. I'll be fixing that next week.

Originally Posted by nuclearnerd

This is a really cool project, and I'm anxious to see the final result commercially available. Although I would be even more excited if you could make your own final stage as well. The Vex final stage has really insufficient mounting strength at high ratios. Two #10 bolts isn't enough to hold the reaction torque (above 100:1 on a bag motor) in our experience.

Thank you, I hope to be able to make this a commercial thing eventually.
We have used the side mounting holes in the past to hold our VPs, so doing that could help. You could also cut 2 more mounting holes such that it holds the VP together; you would use the 2 corner holes that currently house #8 bolts that hold the VP together.

Originally Posted by Chris Endres

Nice! Ever since you posted the CAD a few months ago, I was eager to see it come to life.

Good luck on the final iteration! Hopefully this will be something VEXPro will look into in the future, it really is a nice way to get a compact and high reduction stage for Versa Planetaries.

Originally Posted by cbale2000

While I'm still of the opinion that cycloidal gearboxs are magic, the thought of a 20:1 or higher reduction with limited or zero backdrive in a VersaPlanetary form factor is VERY appealing to me. It could also be a way more flexible and compact solution for applications that many teams currently use worm gearboxes for.

My thoughts exactly! Using the plastic gears allows for ratcheting, so the gearbox doesn't get destroyed by over-torquing the output (like in a collision with another robot), but metal gears if properly constructed would be able to shear the 1/2" hex output before the gearbox fails.

[Cothron Theiss]

This is a bit of a resurrection, but has there been any progress on this design? I think this could be a great option for teams wanting to power arms or winches or a host of other subsystems.

[AdamHeard]

Originally Posted by Cothron Theiss

This is a bit of a resurrection, but has there been any progress on this design? I think this could be a great option for teams wanting to power arms or winches or a host of other subsystems.

Why not just use a stock versaplanetary?

[Cothron Theiss]

Originally Posted by AdamHeard

Why not just use a stock versaplanetary?

Why not use a single 33:1 stage instead of a 3:1 stage and a 10:1 stage? Also, I'm a fan of non-backdriving gearboxes, and this is a much more robust option over the window motors.

[AdamHeard]

Originally Posted by Cothron Theiss

Why not use a single 33:1 stage instead of a 3:1 stage and a 10:1 stage? Also, I'm a fan of non-backdriving gearboxes, and this is a much more robust option over the window motors.

One has thousands and thousands of hours of FRC in competition testing, the other does not.

Easy enough for me.

[cbale2000]

Originally Posted by AdamHeard

One has thousands and thousands of hours of FRC in competition testing, the other does not.

Easy enough for me.

Every new design has to start somewhere. When Versaplanetaries first came out they didn't have nearly the testing hours they do now.