LAST Wheel question
 

I see that a lot of teams use lawnmower wheels, and I want to know are they using plastic or metal wheels, and do most teams just drill holes to mount sprockets. Also how do lawnmower wheels hold up?

Re: LAST Wheel question
 

we tried metal ones in OCCRA a couple years back. drilled holes to bolt the sprockets onto..... we'll just say we won't be going back to that design again.
the rubber tread just wasnt even close to grippy enough to be competitive in that sense. and we had duallys too. but then again we mightve pickesd the wrong type. ive seen many teams succeed very well with them. but i just dont like them anymore.

Re: LAST Wheel question
 

You don't use straight metal wheels in FIRST. If you use metal wheels, make sure you put belting around the edge as a traction device. There is a rule in Section 4 about no damaging the playing field with a traction device (and no metal on carpet). Also, I think most FIRST teams use wheelchair wheels.

Re: LAST Wheel question
 

I know that you can't just use metal wheels, but what wheels can you use to put conveyor belt material on. Also how can I attach caster wheels to a drive shaft?

Re: LAST Wheel question
 

Any you like. Metal wheels are fine with belting, Skyways are often modified with belting. I'd go with a Skyway. Grind down the tread 'till it's flat and close to the plastic. Use screws and drive them as deep as you can get them (or come up with your own unique way of attaching).

Re: LAST Wheel question
 

for doing six wheel drive would it be easier to use a keyed shaft or drive the wheels?

Re: LAST Wheel question
 

It's a loaded question, first determine what wheels your going to use, then your desired speed.(s) your wheels will tend to drive how you mount them, The Skyway 6 and 8 inch will only work with a 3/8" shaft unless you do some serious custom mounting. The Skyway's with an inner tube only drive with a 5/8" keyed shaft. If going with a shaft pay attention to what the shafts will be mounted in. Steel pillow blocks get heavy very fast (we built our own out of "cutting board" plastic one year) Search the forums for the Atwood gearing xls spread sheet it's a big help in picking sprockets and gears with out redoing the math every time. The wheels from IFI let you decide how you are going to go, If you are willing to spend the money. Hope this gives you some ideas.

Re: LAST Wheel question
 

Our second robot used 8 inch plastic lawnmower wheels (Home Depot @ about $10 per wheel). We just drilled 3 holes and mounted the sprocket using 1/4-20 bolts and spacers. That robot just went through it's third build and those wheels still have tread on them. Even being run on asphalt several times. We've also used wheelchair casters when we needed something very light and have moved up to go-kart wheels last year.

Re: LAST Wheel question
 

I think I am going to try lawnmower wheels just based off of cost. Our team has a really small budget so if they work it will save us a lot of money. Are there any specific things to look for in lawnmower wheels.

Re: LAST Wheel question
 

Colson wheels are cheap, maybe even cheaper. But you'll have to make hubs for them.

Re: LAST Wheel question
 

If you're going to attach the sprocket to the wheel so the wheel spins on the staft (rather than firmly attaching the wheel to the shaft and driving the shaft), I'd spend the few extra dollars and make sure I got the wheels with the ball bearing hubs. I'm not sure I'd trust broaching a plastic wheel and using a key to keep it on the shaft to drive it. It probably will work as I broach plastic gears and generally they're fine but wheels can take a bit of shock. If you're going to drill through the wheel disk to attach the sprocket, don't get the wheels that have open spokes. :yikes:

Re: LAST Wheel question
 

Yeah I'm planning on getting the ones with bearings and drilling through the wheels. How is the traction with the wheels?

Re: LAST Wheel question
 

If you're building a 4 wheel drive robot, the traction on the 8 inch wheels we used is pretty good. Not so much grip that you can't turn relatively easily. 4 wheel drive is always a pain because of the tradeoff between traction and turning, not to mention the odometry problems when you start getting fancy.

Re: LAST Wheel question
 

What do people think about the skway beadlocks or the 8x2 skyway pneumatics?

Re: LAST Wheel question
 

The pneumatics we have both with the standard and the larger tread and tube on them. They give good grip with and the standard are pretty easy to turn, They do bounce. The larger tires have tremendous grip and take two motors a side to turn tank style. The hubs we used only drove with the 5/8" keyed shaft, they have an aluminium insert and take abuse very well. The beadlocks tend to be heavy and have a large amount of slip in all directions on carpet. On the plus side, they don't bounce

Re: LAST Wheel question
 

What pneumatic wheels did you have? They were the keyed hub correct?

Re: LAST Wheel question
 

I'm going to just put this out there really quickly. Don't use the beadlocks ever on a robot. FIRST once gave them out with the kit and they just ruined a lot of teams that were forced to use one of the worst wheels(for FIRST Robots) you can find. They're big but have a small traction area, if you grind them down you'll find that they aren't tough at all and will wear away any tread you do cut into them.

The pneumatics on the other hand are great! The big 8" were used on the strongest robot my team has ever built back in 2002 and still haven't been able to top. We are trying to best it this year with tank treads but who knows, they're pretty great.

Re: LAST Wheel question
 

How did you power the 8" pneumatics? You can't get them keyed so I am a little curious.

Re: LAST Wheel question
 

A couple of other things I remembered (you can't expect too much out of me before lunch :rolleyes: ) Try to make the holes for mounting the sprocket as close to the rim of the wheel as practical as this will reduce the bearing load on the plastic disk of the wheel. Also, to spread the bolt load be sure to put flat washers on both sides of the wheel when running the bolt through the wheel disk to go through the spacer to the sprocket.

Re: LAST Wheel question
 

So i decided that lawnmower wheels didn't look sturdy enough. All of the ones I could find had a ton of play in the bearings whiich would probably through off the chain and sprockets.

Re: LAST Wheel question
 

Beadloks make great flywheels for propelling soccer balls into goals....

Re: LAST Wheel question
 

The Bead-Loks are by far the most popular wheel. They are backlogged at least a week here at the factory. ;/ :mad:

Re: LAST Wheel question
 

Thanks everybody. I think I am just going to go with the kop wheels and grind them down and probably add conveyor tread.