Do you guys know a good place to get these kinds of wheels?
Or even a small variation in the wheels like the ones in this picture?
www.andymark.biz
http://www.omniwheel.com/ has similar stuff.
buy from andymark.biz for sure.
andymark inc. is run by fellow firsters, in fact some of the best firsters you’ll ever meet. check out their 6" and 8" trick wheels. i had one recently and it was sweet.
those trick wheels do look sweet but are their any cheaper places to buy them
Yea those are home made, took me around 3 weeks from benchmarking to find a good design, design em, prototype em and make em. but after that it was a very good tool to our success. I would’ve loved to just buy them from andymark.biz but it makes you feel better if you make the parts. well good luck this season!
does anyone know a cheaper place to buy omni wheels (8 in or larger)
ive been looking online for a couple hours and just cant find any site
they are important to our design but $86(wheel & hub)+shipping for one is just not in our price range
Is is possible that you could make your own, but the cost in time spent on labor would probably be more than the $86 you’d pay AndyMark. But, if you like to work for cheap…
Another option is to get the 2" omniwheels from www.omniwheel.com and put a few (5,6,8?) around a plate or something, but that would probably cost just as much and your robot might drive like a flinstones car.
One question, why so large? Why isn’t the 4" that www.omniwheel.com sells, big enough for your needs?
If you could settle for less than 8 inches, you could try the 4" transwheels at www.omniwheel.com. I’d just warn you to make sure they are inside your frame or at least protected from direct hits from other robots.
8 in is needed for the right center of gravity on our robot
Could you elaborate? I can’t really see a good reason to use 8" this year.
You can also try making your own hubs for AndyMark wheels to save a bit of money. Depends on how you plan to mount to the shaft, but it is a pretty simple part.
For the past 8 years, I have not found any of this size. This is why Mark and I saw an opportunity and went with it.
Notice that we provide the complete CAD files (.stp format) for these 8" trick wheels on our site. The side plates could be cut on a CNC mill, a waterjet cutter, or a laser cutter (or with more difficulty on a mill with an indexing head). You can take these files, make prints from them, and build-your-own wheels without permission from us. This design is not proprietary. The rollers can be made easily from polycarbonate, nylon, delrin, or cut with more difficulty from a softer rubber. Be sure to smooth the sharp edges of the plastic to not damage the carpet on the playing field.
Good luck,
Andy B.
My team has been unhappy with the Skyway wheelchair wheels in past years, mostly due to their apparent lack of traction. We were considering ordering some of the omniwheels from andymark.biz. But I noticed that the coefficient of friction for the Skyway wheels is at least .2 higher in the forward/backward direction. We want to be able to have enough traction to push and resist being pushed, but we also want to be able to turn smoothly. Last year we used some Skyway pneumatic wheels that had so much friction our robot would not turn until we used vacuum hose and cable ties to make some cheap omniwheels out of them.
Maybe I’m confused as to how these sort of things work. Wouldn’t it be best to have a high forward/backward coefficient of friction to have pushing power, and a low sideways coefficient of friction so that the wheels do not resist sliding sideways across the carpet when you want to turn?
(Team 833 has a problem in that we have no carpet in our shop so when we drive our 'bot around on the concrete floor we don’t get a very good idea of how it is really going to maneuver. When we want an accurate field test we have to pack it into the bed of a truck and haul it 1/4 mile over to our schools carpeted cafeteria).