Urethane Drive Wheel Questions
 

We are interested trying some new wheel options out for fun (and maybe style) in the off season. Though we are going to have a new facility with machine shop by January (fingers crossed!), right now we need to do it with off-the-shelf.

I found these, and they look promising. http://www.sunray-inc.com/online-store/drive-wheels/

We would be getting the aluminum hub, 4" x 1.25" models. Though expensive at $30 each, it's not a huge investment and may be an upgrade. We would broach the hub ourselves for 1/2" hex/thunderhex shaft. My questions:

• Has anyone tried using urethane tread on FRC carpet?
• What were your results, in terms of CoF relative to other popular choices, like Colsons and wedgetop blue Nitrile?
• What did you find in terms of durability?
• What durometer rating(s) did you try?

Also,

• What size bore would you recommend for finishing with the 1/2" broach?

Thanks, I look forward to your responses.

Re: Urethane Drive Wheel Questions
 

Typically, you bore out to .5 inch diameter, then your broach with the .5 hex broach

Re: Urethane Drive Wheel Questions
 

The wheels are rated at 800 rpm, so anything faster than 14 ft/s on a 4" wheel is going out of recommended spec.

Have you tried out Colsons yet?

Re: Urethane Drive Wheel Questions
 

Maybe a member of 841 can chime in. They made similar wheels using polyurethane tread from the same company. They talk about it in this thread.

Re: Urethane Drive Wheel Questions
 

Yes, we've used Colsons for the past several years and we love them. This is more for the learning experience; maybe the result will be improved performance too, though that is a secondary goal.

Re: Urethane Drive Wheel Questions
 

Thanks for that link, that was really helpful. Yes, that's pretty much what we want to accomplish.

Re: Urethane Drive Wheel Questions
 

A few years back team 118 made wheels that looked very close to these. They seemed to go through the wheels quickly but that may have been because of the hub material being plastic not aluminum. ;)

Re: Urethane Drive Wheel Questions
 

IIRC, that was just the wheel itself that was custom made, I think they still used tread as the traction surface.

Edit: Never mind, I think they actually did make wheels like that...wonder why they stopped, probably something to do with durability maybe. They look pretty cool though in the videos.

Re: Urethane Drive Wheel Questions
 

We built a variant of these during the off season using 60A Durometer Urethane. The CoF with the 60A was approximately 1.3.

We bought a 4ft tube of the urethane from Sunray Inc with an ID 3.25in and an OD of 3.75in for ~40$ off of McMaster

The inner diameter of the wheel was 3.5in, which means we streched the polyurethane .25 inches. The rims were made in halves so they could stretch the urethane, eliminating the need for another method of attachment.

I would recommend about .25 inches between the inner surface and the outer wall, since anything less than that tends to fall off the rim.

We also cut a groove into the urethane so that it sat flush with the edges and increased the surface contacting the carpet.









Benefits:

• Smooth ride, no jittering that the zip tie mount method can produce
• Easy to replace
• Durable
• Can be anodized, and the tread comes in any color. Useful for robot branding.

Cons:

• Expensive
• Essentially Colsons
• heavier, since wheels are aluminium
• LOTS of machine time

Video of base

Re: Urethane Drive Wheel Questions
 

https://ccisdrobonauts.org/uploads/f...a3593a1679.png

This is the bot I'm talking about.

Re: Urethane Drive Wheel Questions
 

We used 30a urethane for our intake wheels. We didn't do any scientific testing but we compared them anecdotally with fresh Vex colsons on carpet and if anything the colsons were grippier on carpet. After testing a number of durometer samples 30a is as low as I would go for any function. The urethane also tends to get covered in tread dust that significantly lowers traction.

They worked excellently as intake wheels though and we definitely plan on using them in the future for other functions.

Re: Urethane Drive Wheel Questions
 

We do have a set of orange urethane wheels, they seem to grip very well,but they seem to get covered in tread dust easy, we use them mostly for low power applications.i wouldn't use them as a main drive wheel, as I don't know how reliable they are.
Our wheels aren't as high grade, and are plastic, not steel.

The only thing I can see wrong with these is the issue of damaging the wheel if it starts losing traction, like trying to drive it up on a platform from recycle rush and getting the bot stuck. And of course, applications where scrub friction is high. They would be perfect for a intake on a robot.

Re: Urethane Drive Wheel Questions
 

I actually called the company about a variant of these about a year ago. They say they are rated for 800 rpm but that is due to balancing. They said this is so people don't order wheels or rollers for high speed applications without their knowledge. I clarified with them that up to 1200 rpm would be fine and still not require additional balancing. They also recommended that if I was using it for a shooter wheel (like 2013 disk shooters) I would have to note a high speed use and request balancing (I seem to remember up to 16000 rpm being ok but you could call again to make sure). They were also very nice and sent sample disks of about 10 different types so I could compare relative friction and durability between them. Also a caution, they can cut treads into the material for you for extra grip but unless you are ordering 100's of wheels all treads were hand cut as opposed to molded (molds cost 500$ at the time) and this boosted the cost quite a bit. Lastly, they at the time would take hubs to make the wheels from so you could machine your own or they could machine them for you (ex: custom spokes or team number) but their machine time was fairly expensive. You can easily blow 399.99 on one wheel with all the fixings.