pic: CGX-104 cycloidal versaplanetary external

[asid61]

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[cad321]

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.

[Lil' Lavery]

My equations?

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

[GeeTwo]

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:

     Cycloidal Ratio
VP    45    40    36
-----------------------
 3   135   120   108
 4   180   160   144
 5   225   200   180
 7   315   280   252
 9   405   360   324
10   450   400   360

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

[asid61]

Originally Posted by GeeTwo

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:

     Cycloidal Ratio
VP    45    40    36
-----------------------
 3   135   120   108
 4   180   160   144
 5   225   200   180
 7   315   280   252
 9   405   360   324
10   450   400   360

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

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.

[cad321]

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.

Originally Posted by asid61

You distributed a solidworks model with the cycloidal gear generated from equations on a spreadsheet.

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

[asid61]

Originally Posted by cad321

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.

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.

[ajlapp]

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.

[asid61]

Originally Posted by ajlapp

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.

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

[ajlapp]

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

[asid61]

Originally Posted by ajlapp

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

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.

[asid61]

Originally Posted by Lil' Lavery

My equations?

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

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