Mecanum Wheels

[Jeff 801]

Originally Posted by Ether

nice photo.

Did you use ball, roller, or journal bearings for the rollers? Can't tell from the photo.

The bearing surface is nylon on a 1/4-20 bolt (the nylon rolls on the shank of the bolt and not the threads) And between the neoprene roller and the fin there is a Hard Fiber washer from mcmaster

[Ether]

Originally Posted by Jeff 801

between the neoprene roller and the fin there is a Hard Fiber washer from mcmaster

When the roller is axially loaded toward the fin, is the neoprene rubbing against the Hard Fiber washer ?

[Jeff 801]

Originally Posted by Ether

When the roller is axially loaded toward the fin, is the neoprene rubbing against the Hard Fiber washer ?

Yes but with that said the coefficient of friction between the neoprene and the hard fiber washer is greater than that of the hard fiber washer and the aluminium hub so there is just about no rotation of the washer relative to the roller. I hope that make sense. If I was to remake them i would have done it more like how 357 did it this past year with a nylon core and a molded urethane rubber outside.

[Ether]

Originally Posted by Jeff 801

the coefficient of friction between the neoprene and the hard fiber washer is greater than that of the hard fiber washer and the aluminium hub so there is just about no rotation of the washer relative to the roller. I hope that make sense.

Yeah, I realized that after I hit the "send" button.

If I was to remake them i would have done it more like how 357 did it this past year with a nylon core and a molded urethane rubber outside.

The axial loading forces on the rollers can be quite high, so anything you can do to reduce end-loading friction would be beneficial. Perhaps three or four very thin Teflon washers, for example. Is the bolt nickel plated?

Minimizing axial free-play also minimizes losses.

How did you determine the roller profile?

[Jeff 801]

Originally Posted by Ether

Yeah, I realized that after I hit the "send" button.



The axial loading forces on the rollers can be quite high, so anything you can do to reduce end-loading friction would be beneficial. Perhaps three or four very thin Teflon washers, for example. Is the bolt nickel plated?

Minimizing axial free-play also minimizes losses.

How did you determine the roller profile?

If I was going to use this in more of an industrial application I would use R4 bearings a polycarbonate core urethane outside. But for where these are being used nylon is good enough and they are zinc plated bolts.

As for determining roller profile I made a spline having reference points every 1/8 inch. I have attached 2 pictures showing the sketch in CAD and the finished assembly.

[Ether]

Originally Posted by Jeff 801

If I was going to use this in more of an industrial application I would use R4 bearings a polycarbonate core urethane outside. But for where these are being used nylon is good enough and they are zinc plated bolts.

As for determining roller profile I made a sweep having reference points every 1/8 inch. I have attached 2 pictures showing the sketch in CAD and the finished assembly.

This looks great! Nice circular contour. If you're interested in the math, I posted a couple of short papers here showing two different ways to derive the formula for the roller profile.

You said it was used in a "high capacity application". What was that?