pic: CGX-104 cycloidal versaplanetary external
 

Re: pic: CGX-104 cycloidal versaplanetary external
 

I love the compact design. Perhaps designing a small coupler that goes from a versa planetary to this would be something people would find useful. Hope to see some CAD files soon.

Re: pic: CGX-104 cycloidal versaplanetary external
 

My equations? :confused:

Thanks for the credit, but I don't think I ever got around to finding you any equations.

Re: pic: CGX-104 cycloidal versaplanetary external
 

As I understand it, the advantage of cycloidal is the larger ratio of reduction available in a single stage, improving efficiency. Stacking gearboxes that match VP ratios would give up that advantage.

If you made cycloidal gearboxes at ratios of 36:1, 40:1, and 45:1 that could take a VP output as input, then with a single VP and a single "VC" (VersaCycloidal) stage, you could cover the range from 108:1 to 450:1 with no gaps larger than 12.5%.

Here's the table:

Of course, you must put the versaplanetary first because they couldn't take those large output torques.

Re: pic: CGX-104 cycloidal versaplanetary external
 

You distributed a solidworks model with the cycloidal gear generated from equations on a spreadsheet.
EDIT: That would be s_forbes, not you. Sorry.

Re: pic: CGX-104 cycloidal versaplanetary external
 

The problem is, a 10:1 reduction is pretty much the biggest size you can make using 1/8" pins and a 0.03" eccentricity. If I made the gearbox a little bigger, I could add more reduction.
I figured the low backlash and backdrive resistance would be worth it.

Re: pic: CGX-104 cycloidal versaplanetary external
 

Another advantage to this over a vp to consider is that at the moment, from looking at the renders available, this might be machinable by a team with some cnc access. Whereas a vp is something you must buy. For some teams buying the cots item is easier, for others, getting the machine time is easier.

Could you share the link? I can't seem to find it on chief.

Re: pic: CGX-104 cycloidal versaplanetary external
 

This is CNC-able, but some parts, such as the output shaft, would require annoying setups. I might try and work on that later.

It's not Lil' Lavery, it's s_forbes, my bad. I can update the description.
This post: http://www.chiefdelphi.com/forums/sh...47&postcount=7
With the zip file.

Re: pic: CGX-104 cycloidal versaplanetary external
 

Very nice. Glad I see others working on this technology.

FYI...from my own experience building these, the 0.030" eccentricity will be violent and rob efficiency.

It doesn't seem like much, but spinning at speed it's wicked.

Re: pic: CGX-104 cycloidal versaplanetary external
 

Thanks for the advice. I'm trying to figure out how to add a counterweight without needlessly using space and weight.

Re: pic: CGX-104 cycloidal versaplanetary external
 

Everyone of these units I've ever seen has either had multiple wobble plates out of phase for balancing or a dedicated balance weight.

There's no free lunch.

It's no coincidence that you only see these types of drives in major industrial applications where a bit of extra mass and volume is worth some of the cycloid's benefits.

Here's an unbalanced unit designed to work with RS-550 and RS-775 motors built for the 2012 FRC season.

You can see that this unit is very polished and was even intended for production...however, its promise didn't match with its performance.

https://www.dropbox.com/s/mthooimzm0...42.02.jpg?dl=0

Re: pic: CGX-104 cycloidal versaplanetary external
 

I was thinking of putting a second gear of the same mass 180* out of phase, but on the same shaft, such that I would basically be getting the face width of both of the cycloidal gears in strength. So essentially having multiple wobble plates, yes.

Re: pic: CGX-104 cycloidal versaplanetary external
 

You must put the second and/or third plate must be on their own eccentricity that is also out of phase.

Re: pic: CGX-104 cycloidal versaplanetary external
 

I have to say, this looks like a fun engineering challenge, and good on you for designing this.

In regards for a team machining this though, I always try and recommend buying as many parts as possible (of course this depends on your team's budget however), rather then machining them. The reason is, you can put that much more time into either designing, programming, or practicing with your robot.

In the first few years that I was on 772, we machined a lot of our own parts. However, when I started to design the robots we transitioned to buying more COTS parts. We focused on designing more, rather then machining. And we were "done" the robot a week earlier then normal, and had a lot more practice with it. The robot's level of performance went way up too.

Remember, your robot isn't going to become a great competitor because you custom built a transmission, but you can get better by designing the whole robot better, having a great strategy, having reliable parts (with easy to find replacements), and having more practice.

Re: pic: CGX-104 cycloidal versaplanetary external
 

While designing this, I made sure to make it such that each could be machined with only access to one side (with the exception of the output shaft, no flipping of parts is required). That being said, I more designed it as a "replacement" for a versaplanetary; hypothetically, if I had access to Vex's machining resources, how would I be able to use them to make a gearbox? The end result actually requires less machining in some ways, although I'm not 100% certain how they make the output shafts on the versaplanetaries.
I agree with you though, COTS parts and driver practice is magic. A few days with our robot between SVR and Champs doubled our potential score.