2" 3DP Mecanum Wheels

So I decided to design a custom ~2" mecanum wheel to be 3D printed as a CAD exercise. It uses two M3 bolts in order to attach both parts of the wheel together, and an M3 bolt as a shaft for each roller. Overall dimensions are ~53mm (2.1") OD, 24mm (0.945") thick.

I had two main objectives with this design: to (somewhat) learn how to use OnShape - as I’m a SolidEdge user but I also use a MacBook, and to design the wheel so that it could be printed without supports - this is because all of the other designs I saw on CD/Thingiverse require some kind of support in order to print them.

You can see the design here: https://cad.onshape.com/documents/2ab0ac6d17bf9f7010650432/w/d86e3bbc6f3e2f5e7af8cdc3/e/7b4f489c9972a7f3818a8641

I finished printing the previous revision a few minutes ago on my Prusa i3 MK2, and it looks pretty promising IMO:

The Prusa handled it pretty good, since everything is 45 degrees and there isn’t much overhang. The total print time per wheel is about 3 hours. Both the top and bottom parts took 1hr each and the 6 rollers took about 1hr altogether, although this was printed with only 2 perimeters (in order to save material and time).

I’m looking forward to testing this with an actual motor. A possible improvement would be to replace the M3 bolts with M2.5 for weight savings. Another one I thought of is using lathed, non-printed rollers like in the TTB wheel, maybe with heatshrink/surgical tubing over them for improved traction.

Would love to hear your feedback about this little project :smile:

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The biggest issue I see here is the shape of the rollers. Mecanum rollers are usually designed such that as the wheel is rotated, the outer contour of the rollers is a cylinder. This means (IIRC) that each rollers’ shape is a piece of an ellipse rotated around its axle (the roller’s axle, not the ellipse’s) and truncated to fit the bearings. If you are using this as an intake for something really compliant (like a balloon or other inflatable ball) you might be OK, but driving on these would be bumpy.

Depending on how much overhang your 3DP system allows, you could do those rollers in a vertical configuration with little extra support, or you could do “half rollers” with no overhang at all.

I still suggest blunting those ends so you don’t pop the CARGO.

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This is, indeed, intended for intaking (currently cargo). While I still haven’t actually tested this, the TTB/33 wheel uses vertical rollers and the testing looks pretty promising. I am planning on designing an ellipse-based roller, although I feel like the initial testing can be done without one.

This makes sense. Need to check whether we have a chamfering insert for the lathe in the shop. Thanks for the feedback!

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