pic: A mechanum wheel that shouldn't bump around at all.

[Hawiian Cadder]

in actuality the arm will go all the way out, and match the profile of the roller and be coated in delrin, that will slide and will make it perfect, the way i did it was to assume that each roller had to have an arc that would look exactly like a circle when viewed from 45 degrees, thus the line that defines the outer edge of that roller is an elipse with one dimension being 8, the diameter of the wheel, and the other dimension being 8/sin(45) or about 11.3, this makes the profile of the roller a perfect circle from a 45 degree angle. the rollers are just revolves with that line as the edge. the arms are .375 inch thick 7075 aluminum alloy, and according to solid works, this wheel should hold at least 200 LBS safely. the total weight of the wheel is 1.8 LBS, it is 2.6 inches wide from roller tip to roller tip, and is 8 in diameter, the axle hole will have have a hub or something to attach it to the motor. the method for manufacturing the rollers is to print off a mold on our 3d printer, then use urethane, coated in rubber. overall it should be pretty sweet.