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 This isn't about practical, it's about having fun and thinking outside the box... tetrahedron.... whatever....:rolleyes: - Cyberguy34000 [more] |
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Hey CD,
Another product from team 1323 and team 11. One of our sponsors donated 13 of these awesome wheels aka Sunrise Medical. This is a 6 inch wheel which has to be lathed down to a 5 inch diameter due to the fact that is has a weird groove on the outside which does not allow us to put tread on it. The bore is 7/8, perfect for a 3/8th's bearing. The wheel itself is plastic and weighs .05 lbs. It is made to survive 8 years on a wheel chair. Just a tad bit of background, Sunrise Medical is the Worlds leader in Wheel Chairs and other medical equipment. They donate $1500 dollars worth of materials every month; such as plastics, aluminum and wheels not to mention 24 V motors for offseason go-carts. The only problem we have is how do we attach a sprocket to it?
Help and opinions are welcome and greatly appreciated.
Discussion
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12-26-2008 10:42 PM
sdcantrell56
Re: pic: Madtown Marauders Wheel
That looks awesome. Now what is the weight and its dimensions? Also how are you driving it?
12-26-2008 10:45 PM
R.C.
Re: pic: Madtown Marauders Wheel
Sorry, took a bit to write the description.
12-26-2008 11:00 PM
Cory
Re: pic: Madtown Marauders Wheel
To be blunt, there is no way those spokes are not going to break.
12-26-2008 11:06 PM
Akash Rastogi
Re: pic: Madtown Marauders Wheel
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Originally Posted by Cory
To be blunt, there is no way those spokes are not going to break.
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RC did tell me that Sunrise Medical told them the wheels were tested and tested again. They were concluded to be stronger than Al.
RC, did they say what plastic it is? Because although I would trust their engineers, I am a bit skeptical. Don't know if they'd be fit for an environment such as FRC fields and matches.
12-26-2008 11:11 PM
R.C.
Re: pic: Madtown Marauders Wheel
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Originally Posted by lilstogi11
I'm wondering the exact same thing. Unless the picture is at an angle and we don't see the full spoke?
RC did tell me that Sunrise Medical told them the wheels were tested and tested again. They were concluded to be stronger than Al. RC, did they say what plastic it is? |
12-26-2008 11:15 PM
Chris Fultz
Re: pic: Madtown Marauders Wheel
You might be able to use AndyMark hubs and attach sprockets to them.
You can use the axle to align the hubs and wheel and keep things centered, and then possibly bolt through front to back (i think the hubs have six holes) and sandwich the wheel between two hubs or a hub and a plate.
12-26-2008 11:18 PM
sdcantrell56
Re: pic: Madtown Marauders Wheel
You could maybe try pressing in a keyed hub of some kind possibly with jb-weld or some other strong epoxy as well. Unfortunately those wheels look really difficult to adapt to.
12-26-2008 11:44 PM
Jim E
Re: pic: Madtown Marauders Wheel
how about gluing a plate to the outer wheel rim and bolting the sprocket to that?
12-26-2008 11:57 PM
R.C.
Re: pic: Madtown Marauders Wheel
Here's a link to a better view:
http://www.team1323.com/Pages/wheel1.html
12-26-2008 11:59 PM
artdutra04
Re: pic: Madtown Marauders Wheel
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.
12-27-2008 12:01 AM
=Martin=Taylor=
Re: pic: Madtown Marauders Wheel
[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.
12-27-2008 12:27 AM
Akash Rastogi
Re: pic: Madtown Marauders Wheel
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Originally Posted by Hachiban VIII
[fist shaking/]Although I dare say she’d try and make me proud
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We might hold these off for non competition robots too btw. Doesn't have to be strictly for FRC either.
12-27-2008 03:07 AM
Richard McClellan
Re: pic: Madtown Marauders Wheel
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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. |
12-27-2008 03:26 AM
R.C.
Re: pic: Madtown Marauders Wheel
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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.
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12-27-2008 03:33 AM
Richard McClellan
Re: pic: Madtown Marauders Wheel
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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.
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12-27-2008 04:13 AM
AdamHeard
Re: pic: Madtown Marauders Wheel
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?
12-27-2008 04:39 AM
R.C.
Re: pic: Madtown Marauders Wheel
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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? |
12-27-2008 06:01 AM
Travis Covington
Re: pic: Madtown Marauders Wheel
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.
12-27-2008 09:54 PM
Raul
Re: pic: Madtown Marauders Wheel
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Originally Posted by rc_cola1323
Yeah, they really are .05 lbs. ....
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.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.
12-27-2008 10:12 PM
R.C.
Re: pic: Madtown Marauders Wheel
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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. |
12-27-2008 10:33 PM
Akash Rastogi
Re: pic: Madtown Marauders Wheel
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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.
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As for mounting the sprocket, I would go with Art's idea. U have the machining resources so get to it
12-27-2008 10:42 PM
Vikesrock
Re: pic: Madtown Marauders Wheel
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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.
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Sponsor donations are nice, but the parts always need to be evaluated against the alternatives.
12-27-2008 11:31 PM
R.C.
Re: pic: Madtown Marauders Wheel
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Originally Posted by Vikesrock
If your custom wheel is .3 lbs and is set up for either a sprocket or live axle it will likely be lighter than or equal to the pictured wheel with a setup such as the one Art described to drive it. Combine this with the strength concerns mentioned by some of the posters and you may want to look at what you really gain before deciding to use this wheel.
Sponsor donations are nice, but the parts always need to be evaluated against the alternatives. |
Preseason Madness Rocks!
-RC
12-28-2008 05:59 PM
vivek16
Re: pic: Madtown Marauders Wheel
You could always use them as idler wheels.
From what I've heard, the spokes at not meant to be torqued. Sure they may work fantastically as casters but until you can find a way to test how well the wheel takes torque, you can't trust them powered on a FRC bot.
-Vivek
12-28-2008 08:38 PM
Sam2197
Re: pic: Madtown Marauders Wheel
looks nice. but i agree with a lot of other people. in FRC i dont think it would survive. but off season stuff it would be great to work with. although for a wheel chair it may be great but think about when you put all of that torque on the center of that wheel. it would probable rip apart after a while.
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