Colson Wheel and AndyMark HTD Pulley

[Oblarg]

Honestly, I'm not seeing the ground clearance issue with the belt; if that were a problem, you wouldn't have people running VexPro 72t gears direct-mounted to 4'' omni-wheels, which I have seen work with no problems. Besides, if anything contacts, it'll be the flange, and given the near-redundancy of a flange in this setup anyway it's not exactly clear that there are any real wear issues with that.

Also, while it's nice to keep the traction wheel in a butterfly drive small, 3'' isn't exactly "much too big" - I've seen teams run butterflies with two 4'' wheels which worked fine and weren't particularly heavy.

[pfreivald]

Originally Posted by AdamHeard

Assuming 5mm pitch (GT2 or HTD), that's a 28T pulley. 1.754" PD, 1.875"
Flange diameter (per sdp-si spec). Just posting this so people have a data point to compare to.

I'm really surprised by a 1-7/8" flange on a 2" wheel. That flange is DEFINITELY touching carpet from my experience, but since the traction portion of an octonum is so rarely used I can see that not being a big issue (especially if metal flanged pulleys are used).

For future reference, I bet the c-c is small enough that if there is a flange on the pinion pulley and the belt is reasonably tight no flange is required on the traction wheel pulley.



3" is MUCH too big for a butterfly

Here's a picture of it. Hope it provides valuable information!

[Oblarg]

Originally Posted by pfreivald

Here's a picture of it. Hope it provides valuable information!

Out of curiosity, what cylinders were you using for that octanum?

[pfreivald]

Originally Posted by Oblarg

Out of curiosity, what cylinders were you using for that octanum?

A pair of 1.5" diameter, 6" stroke. Ummm...not sure if Parker or Bimba. We've got the setup down to ~50 lbs for the drive train including electronics and compressor, and absolutely as cheap as we can possibly make it. (Well under 50% the cost of our first go.)

[Oblarg]

Originally Posted by pfreivald

A pair of 1.5" diameter, 6" stroke. Ummm...not sure if Parker or Bimba. We've got the setup down to ~50 lbs for the drive train including electronics and compressor, and absolutely as cheap as we can possibly make it. (Well under 50% the cost of our first go.)

Ah, that's a much larger stroke than I was expecting; our current butterfly drive is designed for 1.5'' bore, 1.5'' stroke cylinders.

[Aren_Hill]

3928 this last year used 1.0625" Bore, 1" stroke pistons for our Butterfly Drive.

[AdamHeard]

Originally Posted by Aren_Hill

3928 this last year used 1.0625" Bore, 1" stroke pistons for our Butterfly Drive.

Just to one up Aren. We used the same bore, but 3/4" stroke.

We used 75% the air he did

[pfreivald]

Originally Posted by Oblarg

Ah, that's a much larger stroke than I was expecting; our current butterfly drive is designed for 1.5'' bore, 1.5'' stroke cylinders.

We use one cylinder per side. We found that it was actually cheaper and lighter to do it that way, rather than have one cylinder per wheel pod. We don't shift between drive systems enough in any given game to give much of a thought to the extra battery drain.

[BBray_T1296]

For all you teams with butterfly drives, have you tried having the rear wheels in the opposite setting of the front wheels? Particularly to adjust your center of rotation for improved local maneuverability? does that even work?