Every year, we get into the situation where we have to choose/design our wheels. We’ve ended up using highly modified 6" skyway wheels for the last couple of years and are generally happy.
However, we have to double them up to get the width that I like (2") and we have to knock out the bearings and make many other time consuming mods.
We have made polycarbonate wheels, but they have fairly low friction with carpet. We have wrapped wheels in timing belt, which had much better friction characteristics, but tended to de-bond.
I wanted to try knurled aluminum, but last year’s rules threw that out.
I like the skyway beak-lok design, but the choices are too big and heavy for my tastes.
So, I wanted to see what other people have used or plan to use for wheels.
Last year we used 4 of the skyway 9x2 beadloks like in the kit. We drilled them out to save weight and we turned them down to 8.5 in di to have a flat tread profile. While the traction was surprisingly good, the wear characteristics were not.
Our wheels change depending on our robot strategy and design. In 1999 and 2000 we used the 8" wheelchair wheels. In 2001 we used the 6" wheelchair wheels. In 2002 we built aluminum wheels that were 5.5" in diameter and 2" wide that we attatched belting material to. In 2003 we built aluminum wheels that were 6" in diameter and 1.25" wide that we attatched belting material to. We’ll decide on wheel diameter and width, or tank tread width for 2004 the first week of the build period.
In previous years and the beginning of 2003, we took the 6" skyway wheels, lathed off all the rubber, and epoxyed a strip of some soft rubber tread stuff to the wheel. It gave us great traction. However, this year, when we tried the same thing, we found that our tread was all but gone after one regional, shredded away by the ramp. So we switched to these other, wider, 6" wheels made from smooth neoprene which weighed 2 lbs each (!!!) but gave us awesome traction, even on the HDPE.
*Originally posted by Bill Gold *
**Our wheels change depending on our robot strategy and design. In 1999 and 2000 we used the 8" wheelchair wheels. In 2001 we used the 6" wheelchair wheels. In 2002 we built aluminum wheels that were 5.5" in diameter and 2" wide that we attatched belting material to. In 2003 we built aluminum wheels that were 6" in diameter and 1.25" wide that we attatched belting material to. We’ll decide on wheel diameter and width, or tank tread width for 2004 the first week of the build period. **
What belting material? How did you attach? Did you have any problems with either slip or delamination at the join of the belt ends?
Hmmm anyone ever think of casting their own wheels using poly urethane?? People do cast their own wheels for sumo robots using this material and it displays great traction. I just received an article on this. Apparently wheel hardness is measured on the Shore A hardness rating. This rating can rage from 10 to 80 where 80 is the hardness of a bowling ball and 10 is soft, gummy material. Though this material has only half the traction of the gum rubber. People also coat the wheels with silicone to improve the wheel’s traction. Silicone can be bought at automotive stores. One last note. Generally high traction wheels tends to loose traction as it picks up dust so make sure that you clean it off with baby wipes.
Last year we used 4 of the skyway 9x2 beadloks like in the kit. We drilled them out to save weight and we turned them down to 8.5 in di to have a flat tread profile. While the traction was surprisingly good, the wear characteristics were not.
Yeah modifying those tires in any way was a bad idea. My friend said that the synthetic material was not really designed to be modified. We lost our treads in the first run of our match.
We use the Skyway 10 X 3 pneumatics for all four wheels. You can order them with bearings or keyways. They saved us last year when we had too much traction and were stalling motors trying to turn. We ran the pressure up to the specified max to reduce the contact patch and could turn again.
In 2002 the belting material that we applied was cut by hand from part number 5994K854 in the McMaster-Carr catalog. We glued the tread to our aluminum wheels, and then used small screws to hold the edges in place. The belting never came off, and wore down a fair amount over 2 FIRST events and an off-season event. We probably should have changed the tread out for new pieces somewhere along the line.
In 2003 the belting material that we applied and used at Silicon Valley was cut by hand from part number 60155K113 in the McMaster-Carr catalog. We glued the tread to our aluminum wheels, and used a few small screws to hold the ends in place. During the regional we ditched the screws because although we didn’t think they’d make contact with the surface (they were pretty well recessed), we wanted to be within the rules as much as possible (regarding no metallic items touching the ground). We used zipties in place of screws to hold the edges of the belting in place. We changed tread Thursday and Friday nights before the pits closed at the competition (the grating on the ramp tore our tread up pretty well). It was a long process which would have been made a lot easier if we had built an extra set of wheels. Oh well… that’s next year, I guess.
The belting material that we applied for Cal Games was cut by hand from part number 5994K854 in the McMaster-Carr catalog. We applied this tread with glue, and held the edges in place with zipties. This material was a lot more resilient in the face of the grating on the ramp, and not that much of a difference in CoF on the HDPE (it was a little less, but we didn’t drive like we were on ice). We had to change one tread (along with many other drivetrain problems that weren’t tread related), and we were forced to secure it with only zipties. We replaced old zipties with new ones after each match down the stretch. After about 12-15 matches in one day, the tread wasn’t as worn as the tread we used at Silicon Valley after only 4-6 matches.
Adam Y,
A parent on our team who works at Northrop-Grumman is going to look into getting us a sample wheel with neoprene casted around it as tread material. I’m really excited to see how that compares to the belting materials that so many FIRST teams currently use.
