Chief Delphi - Where to purchase new wheels.

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Re: Where to purchase new wheels.

When you mention that you can climb ramps with 4" wheels if you do it correctly, what do you mean?

How do you climb ramps with 4" wheels?

Thanks, Travis

Re: Where to purchase new wheels.

Quote:

Originally Posted by Travis Schuh (Post 648352)

When you mention that you can climb ramps with 4" wheels if you do it correctly, what do you mean?

How do you climb ramps with 4" wheels?

Thanks, Travis

Climbing ramps depends on your frame not your wheels. So long as you don't bottom-out with the wheels you are using you can climb a ramp. (But sometimes its easier just to use bigger wheels than designing a different frame)

Here are some other wheels to consider:

Swamp Thing (179) used some really cool wheels in 2005 that roughly match your description.

The wheels came from here.

My team used 8" pneumatics from Skyway last year. They were very cheap and provided tons of traction. So much traction that we had to replace two of them with omnis :o just to turn...

They are listed as the 8"x2" wheel on the bottom of this page.

Re: Where to purchase new wheels.

Quote:

Originally Posted by Richard (Post 648327)

Many previous threads have explored the observed principle that wheel traction depends strongly on material and texture, while it is mostly independent of contact patch area. So 2" wide wheels don't grip (much) better than 1" wide wheels if other parameters are equal.

However, double the width means half the load-per-contact-area and therefore half the wear, so wider wheels will keep their traction longer -- i.e., more matches between tread changes. And wider wheels will resist twisting more than narrow ones, so defenders will have to work harder to force you to change direction -- and your own motors may also have to work harder when you want to change direction.

Another place that relative width comes into play is in affecting the normal force at the wheel. While this won't impact the total normal force of the robot or it's total pushing capacity it can be used to move tractive load around on the robot. (OK, this is a theory and not a proven fact yet.) Why would this be useful? More tractive load at the center wheels of 6x6 yields easier turning by reducing the laterial skidding forces at the corners. How does this work? The carpet that supports the wheels behaves (I believe) like a spring or elastomer locally. By doubling the width of the wheel the 'spring rate' gets doubled forcing that axle to support more weight than it would otherwise. Supporting this theory is the fact that 6x6 drivetrains often lower the center wheels to improve turning.

Re: Where to purchase new wheels.

Quote:

Originally Posted by Travis Schuh (Post 648352)

When you mention that you can climb ramps with 4" wheels if you do it correctly, what do you mean?

How do you climb ramps with 4" wheels?

Thanks, Travis

As has been stated it is all about placement. If you keep the wheels to the outermost extents of the robot you should have no problems climbing. We have used 4" custom wheels for 1 year now (we tested them last off-season on the jeep bot) and we have never had a problem climbing. The ramp from aim high was no problem. Ramps from last year never gave us trouble either.
We use 6 wheel drive with the center wheel lowered about 1/8" with inclined conveyor belting attached. Our wheels are 1" wide and we do wear through tread fairly well but replacement is something we need to keep up on. We are testing new materials this fall.
If you want to CNC wheels in the fall you can. You just can't use them at competition. We make a set each fall and then have a drive base the first week of the build season for programming and prototyping. We have wheels made that week and start assembling them as soon as we get them. and start putting them into the competition frame once it is established.
We looked into the Colston wheels this year to keep stuff COTS but weight & implementation kept us from going that route.
Everybody does it different but nobody does it wrong (except our 05 bot). I hope you find a solution.

Remember KISS.

Re: Where to purchase new wheels.

Quote:

Originally Posted by RyanN (Post 648231)

Also, we do not like the IFI wheels. We are looking for something lightweight as we are probably going to have a 4 motor drive train since we kept on tripping our breakers last year. So 2" x 6" wheels...

Ryan

If you’re looking for something strong and lightweight, you should really take another look at the IFI wheels. I'm not sure why your team doesn't like them, but if you are basing this opinion from the 2006 wheels, you need not worry. They were completely redesigned for 2007 from the ground up based on feedback from the 2006 season.

Over the years, 1114 has used Colson's, Custom wheels, and IFI wheels. We've found that the offer the best balance of light weight, robustness, and price of any wheels going. If next years game calls for a wheeled robot, you can be sure that these are the wheels that 1114 & 2056 will be using.

Re: Where to purchase new wheels.

Overseeing this year's drive train, I have the same task. Essentially, we're choosing our wheels based upon the reliability of the IFI wheels last year and the fact that the IFI wheels come with the 1.875"-diameter bolt pattern that's standard for matching up to several other KOP and non-KOP parts, such as the AM flat #25 sprockets. Since we currently are unsure about our access to machining tools this year, this is a big sell for us.