4" Wooden Mecanum Wheel

[TheOtherGuy]

Originally Posted by squirrel

heh...I used the compound rest. I suggested that the error would be pretty low if we made the half roller as two cones. Kevin figured the angles at 6 and 16 degrees, I set the compound rest to those angles to turn it. then we sanded the lump in the middle to radius it.

Looking back at it, the dowel comes slightly smaller than an inch at the largest, and our estimations cut it down on the inside by another fraction of an inch, which may have made the end of the roller near the nut too small a diameter. Then again, I haven't wrapped it yet... maybe I'll go buy some tape and try that out.

The whole parabola thing is very interesting, thanks for bringing that up! The difference is hardly noticeable in CAD, but there is a slight bulge near the ends of the rollers, despite the rollers meshing perfectly. The third link you provided gave a ghastly equation (well, a few relatively nice equations with lots of substitution ) on the last page for estimating the parabola, yet when I plot it, the length is off by quite a bit (should go to sqrt(7/2))... http://www.wolframalpha.com/input/?i=plot+y%3dsqrt(4-(x^2)/2)-1.5,+y%3d.5-(32(2*.5-(sqrt(4*3.5^2%2b(1/2*sqrt(7/2))^2))(+(4sqrt(2)/+sqrt(2*3.5^2%2b(1/2*sqrt(7/2))^2))-1))/(14*((4sqrt(2)/+sqrt(2*3.5^2%2b(1/2*sqrt(7/2))^2))%2b1)^2))x^2,+x%3d-2+to+2&incParTime=true

T-nuts are a possibility, although that would require changing the entire setup of the rollers so the axle is live. I'm not sure if that's a good idea with 3/16" plywood, but press fitting a small piece of the aluminum rod into the hole might give it enough strength.

Originally Posted by Matt H.

They make products for this situation!

Hey Matt! How's MIT?
Mr. Forbes mentioned those as a first solution, too. It may be worth looking into. I just had a crazy idea that may or may not work, but if it's possible to drill and tap into the end of a #10 threaded rod, maybe I can screw on a small washer onto the ends of the rod.