This little composire picture shows the before and after of our 2002 and 2003 wheels.
In the upper left are the wide Skyway wheels before tooling. They are hard rubber on a plastic hub and you can see that the arch of the wheel surface is evident. Thus the surface area in contact with the playing surface is limited.
Therefore we lathed them with a cutting tool to smooth “slicks” of a slightly smaller diameter.
After experimenting with them last year we found that some tread is desirable. So the next step is to cut the wheels on a table saw using the jig in the middle picture. Each wheel takes nearly an hour to cut the individual treads.
The lower right picture shows the wheels on the Silver Scorpion of last year. The criss cross treads are somewhat visible.
While we weren’t the strongest robot out there were were strong enough to hold two goals and get the Archimedes division title.
We tried to lathe the 9" skyway wheel which i think is the one you have but we couldn’t do it because the rubber is too soft and all that happens is it ripps off… i am wondering how you guys got around that or specifically which tool did you use?
you use a grinding tool in the lathe and it wears it down. A cutter just grabs the rubber and tears out chunks. It will take a while for each wheel but we like it.
We used a standard metal cutter in the metal lathe and it worked GREAT! You just have to take only a little at a time and use a high speed and be sure to use auto feed. This will provide a nicely textured flat surface.
*Originally posted by Devil’s Kid *
**We tried to lathe the 9" skyway wheel which i think is the one you have but we couldn’t do it because the rubber is too soft and all that happens is it ripps off… i am wondering how you guys got around that or specifically which tool did you use? **
Yeah, I noticed that and I think I mentioned them to you guys when I stopped by your pit at the CR.
Metal lathes are great. Most standard metal cutting blades are excellent for non-metal soft surfaces such as rubber, plastic, and wood when the lathe is run at a non-low speed and small amounts are taken off at a time (at a uniform pace, usually accomplished by the auto feeder). As long as you keep the blades sharp and use the lathe with good sense, it’ll do the job quite well.
We simply used a belt sander to remove the material. We then spun the wheel to see if we removed the right amount of material.
You can also drive the robot around outside on rough concrete and have the same effect, but you risk getting all sorts of other junk up inside the robot.
If you don’t have a lathe you can perhaps find a way to put it in a drill press and use a file. You would need a 5/8" or larger chuck or an axle shaft that is turned down, on a lathe. Hrmm.
In the past we put the bot up off of its wheels and had someone with a piece of sandpaper and a block at each wheel and ran the drive train. Its a good way to test the drive train too.
We were also successful at cutting our wheels… and they were withstanding normal usage. However, we still ran into problems on the metal ramp where it just sliced through them. Although, by the pile of rubber underneath the ramps, I would say many others had the same experience.
Last year, we let the metal grate do the work for us. Every match we got better and better traction as the wheels wore down how the grate ‘wanted’ them to wear. some smooth parts, some notches, always pretty evenly round though. In future years, we probably can’t do that same method… I’d suggest like A. Rudolph said, thats what 247 did for OCCRA last year.
One more way you could get fairly even wear for a better traction profile is to tie the robot to a stationary object and run it while on an abrasive surface like a sidewalk. Be sure to cool the motors though.
