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Unread 21-02-2010, 08:57
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Re: Plaction and Omni wheels

Quote:
Originally Posted by Edoc'sil View Post
Ok, so we got our bot up and running last night. Our robot had been unable to turn, but we have omnis in the four corners of a six wheel drive. Watching this thing spin in high gear was pretty crazy. Unfortunately while we were stress testing , one of the treads came off our plaction wheel. We assumed Andymark used a epoxy of sorts to adhere the tread to the wheel, but in reality the tread is only held on by three weak staples. How are we supposed to reattach it? Andymark suggests rivets, but I wonder if that is legal due to rules about metal and the floor. Could we use regular epoxy to adhere the tread?

My other question is why did this happen. Is this a common occurrence? I assume it is because the omni's radius is about .125 smaller making them in effect travel slower at the same RPM. Could this have been that cause of the problem? Do we need to gear the omni wheels so that they are going closer to the same speed? And more importantly, why aren't 8 in wheels 8 in?
The product page for the wheel says that the tread is only held on by the pressure of the wheels clamped together, this lets you swap out tread easily. For rough and wedgetop, installing rivets prevents any slipping and dragging issues. Once you drill the hole and rivet the ends, the rivet sits under the rest of the tread enough that it doesn't really contact the ground. Teams have riveted tread onto wheels for years with no issues, so you should be good. I don't know how strong your epoxy is or how well it would adhere to tread / wheels.

The tread probably failed due to the stress of wheels pulling in opposite directions. Slightly slower omnis probably had little to do with it, I wouldn't fret too much over gearing for 1/4".
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