pic: Swerve again, for fun

[Ether]

Originally Posted by Aren_Hill

...would rather avoid mercury on the robot (sliprings).

Are there not suitable sliprings for this application which contain no mercury?

[Bryce2471]

A few questions immediately pop up for me:
How is the CIM shaft so short? Isn't it against last year's rules to modify motors?
Where would you get the bevel gears, and how much would they cost?
What's the weight?

Other than that, it looks very good.

[tim-tim]

Originally Posted by Bryce2471

How is the CIM shaft so short? Isn't it against last year's rules to modify motors?

By that definition, wouldn't it be illegal to cut/strip CIM motor wires to add connectors of your choice on the ends?

[Thad House]

Originally Posted by tim-tim

By that definition, wouldn't it be illegal to cut/strip CIM motor wires to add connectors of your choice on the ends?

R30 specifically allows wiring, mounting brackets and output shafts to be modified. That rule has been there for years, so I would assume it would stay.

[JesseK]

From the cut-out in the other picture, I'm having a hard time figuring out how the large turning gear is mated to the grey-ish ring that acts as the weight-bearing thrust bearing for for the entire robot. It seems like all of the robot's weight is hanging from this ring which is hanging from the gear?

[Jared Russell]

Originally Posted by Ether

Are there not suitable sliprings for this application which contain no mercury?

A few years back I found it very difficult/impossible to find a non-Mercotac COTS slip ring that was simultaneously (a) rated for FRC current levels and (b) within single-components COTS cost limits. It is possible that you could make your own spring-loaded slip ring, but YMMV with inspectors/rules in a given season.

[Andrew Schreiber]

Originally Posted by Jared Russell

A few years back I found it very difficult/impossible to find a non-Mercotac COTS slip ring that was simultaneously (a) rated for FRC current levels and (b) within single-components COTS cost limits. It is possible that you could make your own spring-loaded slip ring, but YMMV with inspectors/rules in a given season.

It is possible (now), I don't have the link handy but they do exist. It's for use in wind turbines so it's actually got three wires. I've also found a few on various websites that are rated for 30A continuous.

The Mercotac ones are far lighter though.

[Kevin Ainsworth]

It has to be the most compact and lightest swerve to date!
Professional grade designing, I looked through the entire design earlier this year and thought it was brilliant. We tried to design something totally unique but nothing we came up with was as elegant. Thanks for the inspiration!

[Bryce2471]

Originally Posted by Kevin Ainsworth

It has to be the most compact and lightest swerve to date!

What makes you say that? Do you know the weight?

[asid61]

Originally Posted by Bryce2471

What makes you say that? Do you know the weight?

+1. I have a swerve design exactly like this on my computer, except with a 2" colson instead of a 3.25" versawheel, ad it weighs a minimum of 5.3lbs. Still heavier than Bryce's swerve, albeit only very slightly.
Plus, making it into a shifting version requires a lot of weight unless you don't use a COTS shifter shaft.

EDIT: Of course, if anybody could make the design lighter it would be Aren. So it could be lighter actually.

Very nice swerve Aren. It's cool seeing your drives. Are you using a dead axle? Is it possible to flip the cim?

[JesseK]

Originally Posted by Bryce2471

What makes you say that? Do you know the weight?

...

We can presume that Kevin from 2451 has a pretty good guess for how much it weighs when he says

It has to be the most compact and lightest swerve to date!

due to

Originally Posted by Aren_Hill

Showed this to Kevin on 2451 and he took off running and now has a fancy 2 speed version.

[Cash4587]

Just curious, is there any way we can get our hands on the CAD files to take a closer look at the module? I know this may be a stretch but worth a shot too: If a team wanted to build this, would the spec sheet include all the parts that come together to make this?

[AdamHeard]

Originally Posted by asid61

+1. I have a swerve design exactly like this on my computer, except with a 2" colson instead of a 3.25" versawheel, ad it weighs a minimum of 5.3lbs. Still heavier than Bryce's swerve, albeit only very slightly.
Plus, making it into a shifting version requires a lot of weight unless you don't use a COTS shifter shaft.

EDIT: Of course, if anybody could make the design lighter it would be Aren. So it could be lighter actually.

Very nice swerve Aren. It's cool seeing your drives. Are you using a dead axle? Is it possible to flip the cim?

I don't think theoretical weights are fair to compare. If the system isn't made and working, it doesn't matter how light it is.

I could go design a 4 lb swerve now, no guarantee it will work or hold up. Many of the recent designs posted aren't robust enough to survive a season (I think Aren's here would though, as he's fielded 5+ swerves at this point I think).

[Kevin Ainsworth]

Originally Posted by AdamHeard

I don't think theoretical weights are fair to compare. If the system isn't made and working, it doesn't matter how light it is.

I could go design a 4 lb swerve now, no guarantee it will work or hold up. Many of the recent designs posted aren't robust enough to survive a season (I think Aren's here would though, as he's fielded 5+ swerves at this point I think).

Couldn't have said it better.

[asid61]

Originally Posted by AdamHeard

I don't think theoretical weights are fair to compare. If the system isn't made and working, it doesn't matter how light it is.

I could go design a 4 lb swerve now, no guarantee it will work or hold up. Many of the recent designs posted aren't robust enough to survive a season (I think Aren's here would though, as he's fielded 5+ swerves at this point I think).

We're looking at a theoretical model right now, so it makes sense to compare theoretical weights. Kevin's theoretical weight for his shifting design posted a few months ago was ~7lbs IIRC, whereas Bryce's models for shifting designs weighed around 6.3lbs. Even if it wouldn't survive a season as in the CAD, there's at least 0.5lbs to play with to buff it up. And Kevin's design used only small steel miter gears, whereas this design uses much larger steel bevel gears.
Given that, I think it's possible that this weighs more than many designs posted previously. However, it is much more compact, and for many situations that can be more valued than the weight.

If you believed that none of the recent designs can survive the season, then you really should have said so ealier, when those designs were posted.

Also, I found this yesterday:
http://www.chiefdelphi.com/media/photos/34178
So Aren beat himself some years ago.

EDIT: How is the bevel gear constrained axially on the shaft? Does it depend on the wheel to position itself properly?