pic: Madtown Marauders Wheel

[Jim E]

how about gluing a plate to the outer wheel rim and bolting the sprocket to that?

[R.C.]

Here's a link to a better view:

http://www.team1323.com/Pages/wheel1.html

[artdutra04]

It's not hard to use a wheel like this, but get ready for some machining. The easiest way I can think of is to make two plates that sandwich the wheel with half of the spoke profile milled into them each, so they fit snuggly into the wheel. Then use bolts to clamp the two plates together, trapping the wheel and using milled grooves and the spoke pattern to transfer the torque.

Then to power the wheel, either drill a hole pattern into these two sandwiching plates for a dead axle drive train, or make one of the pieces out of aluminum (the other could be polycarbonate to name an example) and broach it for a live axle.

[=Martin=Taylor=]

[fist shaking/] argg... Dutra beats me to it... [/fist shaking]

Terrific their engineers might be, but I don't think my grandmother or her walker would last long in a FIRST match Although I dare say she’d try and make me proud

BTW, your link is broken RC.

[R.C.]

I fixed the link, it was being stupid!

[Akash Rastogi]

Originally Posted by Hachiban VIII

[fist shaking/]Although I dare say she’d try and make me proud

Lol.

We might hold these off for non competition robots too btw. Doesn't have to be strictly for FRC either.

[Richard McClellan]

Originally Posted by artdutra04

It's not hard to use a wheel like this, but get ready for some machining. The easiest way I can think of is to make two plates that sandwich the wheel with half of the spoke profile milled into them each, so they fit snuggly into the wheel. Then use bolts to clamp the two plates together, trapping the wheel and using milled grooves and the spoke pattern to transfer the torque.

Then to power the wheel, either drill a hole pattern into these two sandwiching plates for a dead axle drive train, or make one of the pieces out of aluminum (the other could be polycarbonate to name an example) and broach it for a live axle.

If you're gonna go to all that trouble, you might just want to machine a whole custom wheel from aluminum.

[R.C.]

Originally Posted by Richard McClellan

If you're gonna go to all that trouble, you might just want to machine a whole custom wheel from aluminum.

We do make custom wheels and the weight on our custom ones are about .3 lbs. So I was trying to take advantage of these wheels and we have a ton of these. Machining out hubs won't take as long as making new wheels. Thanks Art for the idea and we will test it out on tuesday of next week.

[Richard McClellan]

Originally Posted by rc_cola1323

We do make custom wheels and the weight on our custom ones are about .3 lbs. So I was trying to take advantage of these wheels and we have a ton of these. Machining out hubs won't take as long as making new wheels. Thanks Art for the idea and we will test it out on tuesday of next week.

That is true, these things look pretty sweet for their weight of only 0.05lbs....that's probably one of the lightest wheels to ever be used on a FIRST robot.

[AdamHeard]

Are they really only .05 lbs? That seems rather unbelievable to me.

I don't think anyone else has said it, but as you describe them I don't believe they'll be legal. They were surplus wheels given away? Not a product they continue to sell and any team can buy?

[R.C.]

Originally Posted by AdamHeard

Are they really only .05 lbs? That seems rather unbelievable to me.

I don't think anyone else has said it, but as you describe them I don't believe they'll be legal. They were surplus wheels given away? Not a product they continue to sell and any team can buy?

Yeah, they really are .05 lbs. When our team found them in the scrap pile and asked him why these are being thrown away. He told us too many for this month. We are making some more in february. We put them on the scale and thatz what they read. Also the first thing we did with the wheel was to break it by throwing it, standing on it and doing random things but the wheel did not flex. I think the wheels are buyable if you contact the company. Afterall they use them for their wheel chairs.

[Travis Covington]

I assume these are designed to be used as caster wheels on the front of wheelchairs, and as such, I imagine would easily last 8+ years with no issues used in that application. However, when you use them for a different purpose (powered wheels driving a robot) the dynamics change drastically and I cannot foresee them having the same life span. That is not to say that it won't work, but my limited experience with some of the higher strength-to-weight ratio materials leads me to believe that any wheel* that weighs .05lbs does not have the strength to make me comfortable enough to use them on a competition robot.

See if you can find out what the material really is, and that alone will tell you if they are truly stronger than aluminum (and exactly what sorts of loads they can handle). There is no sense taking someones word for it when there is enough information out there to double check for yourself.

Let us know what you find out. I am not aware of any plastic material that is less dense than any 6000 or 7000 series aluminum while also being stronger (or with remotely similar strength even).

It couldn't hurt to re-weigh it too and put something else on the scale of known weight to get a basis for comparison. When looking at the second picture, it definitely looks heavier than .05lbs.

[Raul]

Originally Posted by rc_cola1323

Yeah, they really are .05 lbs. ....

Sorry - I do not believe they weigh .05 lbs - maybe someone made a mistake in where the decimal point belongs? Who told you or where did you read a spec that says it weighs that much - you should check your source again.

.05 lbs is less than 1 ounce. There are no materials known to us on earth that are that low in density that can hold 120 pounds in the configuration of that wheel.

[R.C.]

Originally Posted by Raul

Sorry - I do not believe they weigh .05 lbs - maybe someone made a mistake in where the decimal point belongs? Who told you or where did you read a spec that says it weighs that much - you should check your source again.

.05 lbs is less than 1 ounce. There are no materials known to us on earth that are that low in density that can hold 120 pounds in the configuration of that wheel.

Sorry guys, I don't know what to tell you. It is what the engineers told us at Sunrise Medical and it doesn't show up on either our bathroom scales or our scale at school. It measures every .25 lbs. So I guess itz under .25 lbs.

[Akash Rastogi]

Originally Posted by rc_cola1323

Sorry guys, I don't know what to tell you. It is what the engineers told us at Sunrise Medical and it doesn't show up on either our bathroom scales or our scale at school. It measures every .25 lbs. So I guess itz under .25 lbs.

Yea please just find out what material it is. And if you can find a scale that measures even smaller increments that would be cool.

As for mounting the sprocket, I would go with Art's idea. U have the machining resources so get to it