Re: Favorite wheels
 

Our team has always used literal tank treads as our drive system. We're looking to change that this year, with a pre-season 6WD IFI frame, that we can use to test stuff on during the season.

A Couple questions:

Why do people prefer who prefer Andymark over IFI wheels prefer them?

For the teams that use IFI wheels, what size do you use?

Someone mentioned changing the treads on them. How often do they get worn out?

Re: Favorite wheels
 

To be honest, I'm unsure what we need in the specifics you're asking. We love the freedom 4" wheels provide in gearing, and how they are inherently much lighter than larger wheels. We also will never, ever, ever consider running low traction wheels.

The reason we want pneumatics is in case it's 2010 all over again, our robot (and 254's) both crashed down HARD when passing the bump, and we both loosely talked about implementing suspensions but never did. Both robots clearly survived all season. The second I saw 1114's robot I was in love with their use of them as a simple suspension. I'm not a fan of the 6" changing the gearing so much, nor the heavier weight, but the 6" wheels they used would be our current go to option in the future.

The huge issue is weight, it's hard to stomach 1-2 lbs per wheel when you're used to wheels that are .22 lbs each.

In summary, we've love 4" ones. That makes them feasible for swerve as well.....

Re: Favorite wheels
 

I prefer the andymark wheels because I think they are a little more efficient and a little more durable. because the IFI wheels are not perfectly round I would think that they are less efficient (no testing here, just my thoughts) A while ago we had some IFI wheels and they seemed like they wouldn't handle side loads as well as the plastic andymark wheels in the 8 and to lesser extent 6 inch size. andymark wheels also don't require a flanged bearing, so more options are available for bearings (such as the ones that come in the KOP)

Re: Favorite wheels
 

We can get them with a 1/2" hex broached hub.

Our tread almost never wears out. Our 2007 robot did 2 regionals, the championship, 2 off seasons and has been our standard practice bot ever since and we have never re-tread it.

Re: Favorite wheels
 

Plactions are cheaper than IFI wheels in the 6-8 inch sizes, I believe.

For live axles, you need an AndyMark hub to use an IFI wheel live, which is a lot more weight. With AM you can just use Performance wheels.

Other than that, nothing wrong with IFI wheels. If we went dead axle and wanted roughtop tread, we'd use them. The wheels not being round just doesn't matter.

Smaller is better unless you have a design need to go bigger.

Not all that often. Maybe once a season. Wedgetop wears much faster than roughtop. Our tread on AM wheels lasted until we drove the wheel on asphalt for several hours. Apparently that dings up the rivets enough to throw tread? Who'da thunk it.

Re: Favorite wheels
 

Just to add to what Chris said, the tread wear varies noticeably depending on the tread compound. Natural Rubber wears the fastest, sometimes within one hard event, Nitrile Rubber wears a little slower, you can usually get at least two events out of the tread, and Blue Nitrile wears the slowest (As far as I know) usually, most teams can get an entire season out of these treads.

Re: Favorite wheels
 

While we are likely to continue running colson wheels due to thier price to performance ratio, and some unique properties that we've discovered I have been doing some research into semi-pneumatic and pneumatic small diameter wheels.

It seems that the smallest readily useable COTS wheel are the 6" diameter ones 330 and 1114 have used successfully. While heavy I believe a custom rim/hub could go along way to making them lighter and easier to work with.

Another option might be to make custom beadlock style rim/hub assembly to use Remote Control Truck Tires, with foam inside, the foam would have to be adjusted to something more dense than what is currently used in that application, but a semi-pneumatic wheel, with COTS available tread could be rather nice. Has anyone looked into this?

Re: Favorite wheels
 

Wouldn't that be like using a can of "fix a flat" on a car? But with the wheel being semi-pneumatic the material should be able to help define the wheels compressibility (is that a word?) by helping the existing rigidity or the tire material and shape.

Sounds like a neat idea to try, but it would seem you are either going to have to cut a ring shaped donut to put inside the tire or use expanding foam.

Re: Favorite wheels
 

When would we want to use roughtop vs wedgetop?

Re: Favorite wheels
 

Semi-pneumatic RC car tires rely entirely on the foam for support, there is no way to pressurize the tire with air (at least in my experience).

You would have to use a ring-shaped piece of foam, or bend a straight piece of foam. RC car tires have a soft enough bead that I would stuff the tire with foam, then install it on the wheel. The same could be done with robot wheels. Alternatively, the wheel could be two-piece and clamp onto the tire/foam combo from both sides in the same way that airplane and truck tires are mounted on wheels.

Re: Favorite wheels
 

Last time I built an RC car I was in high school, and the one I had used three piece wheels and the rubber tires without an insert. The rims were set up to allow airflow in and out of the tire, do they still make them like that?

Re: Favorite wheels
 

I have too many rc cars, and have spent a lot of time looking at RC car tires for FRC applications. What you used were beadlock rims, which are common enough, but usually not used by most serious RC people.

Most RC tires are going to be a foam for suspension, a one piece rubber tire, and a one piece wheel/hub (the tire bear is glued on). Some hubs come with holes to vent, which is really the wrong place for them (the tire itself should be vented), but that's off topic.

The only RC tires that have rubber even close to possibly, maybe, sort of hold up to FRC applications are made for what is known as 1/5 scale cars (most specifically the hpi baja 5b/5s/5t. Unfortunately, these tires/wheels are in the 6" size range making existing pneumatic tires more desirable for FRC applications.

All of the 3-4" sized tires are simply too weak to hold up to FRC drivetrains. For intakes and rollers, they're still a good option when you want the roller itself to have some give and suspension.

Re: Favorite wheels
 

Concerning an easy interface to 8" pneumatic, when I used them last (with 2849 in Columbia), I made two jigs that allowed the kids on our team to make the modifications necessary to attach a sprocket using only a drill press. One jig help modify the plastic hub, the other modified standard AndyMark sprockets (Andy, why don't you guys put in a mess of additional hole patterns in your spockets to facilitate such monkey business? -- it easy for me to say but I think that you could do it for essentially no cost)

Anyway, my problem is that I've moved twice since then and I am not sure I can put my hands on it. Plus the end result was heavier than I'd like.

This year, my proto chassis is going to use the wheel in the attached photo* I plan to use dead axles (and you probably should too -- unless you have really good reasons not to) and the as shipped standard hub (with my kluge attachment of drive sprockets).

If I use them on our competition robot, we will likely do something else. This AndyMark hub sounds interesting, but if I don't like that, I think I can make a much lighter 200X50 hub that is something akin to IFI's hubs. I would plan on using AL side plates spaced apart by standard plastic spacers from McMaster. These spacers would form the ID of the tire bead. I will encircle these spacers with a thin AL strip that will support the ID of the tube (Strip: 0.032 thick roughly 50mm by 650mm ~ pi X 200mm + 20mm overlap). ... I think it could be light, strong and ... awesome.

But... The devil is in the details.

I should CAD this up and post it. Stay tuned.

Joe J.

*You can buy these from mobilitydirect.com (no ties financial or otherwise) they are not "on the menu" but you can order them just the same see my correspondence below:

Yes we do sell these.
To order please give us a call at 877-914-1830.
Refer to part #080200-3-4
Description: CASTER, 8 x 2, 4-HOLE 2-PIECE RIM, KNOBBY PNEU TIRE, 3/8" PREC. BRGS
Price - $34.65ea

Ron
Customer Service
MobilityDirect.com
info@mobilitydirect.com

Re: Favorite wheels
 

Roughtop v wedgetop is a question of turning and maneuverability. In 2010, out 6WD was roughtop center (for traction and pushing power) with wedgetop corners, for turning. Of course, our centers were dropped.

IMO, the dense spacing between ridges on roughtop treading makes it harder to pivot on roughtop, whereas the spacing on wedgetop wheels allows the ridges to fold over as you turn, making turning easier - though I could be wrong.

Re: Favorite wheels
 

We've always used all roughtop and never really had any issue turning. I'm sure tread material is a factor, but it can be compensated for in your drop distance.