Molded Wheels

Hello, this year we molded our own gripper wheels and wanted to share a little bit of the process to encourage other teams to try this on their own.

We designed a wheel in cad, 3D printed a mold out of PLA and a bearing hub out of Onyx, poured a 2-part polyurethane mix (durometer of 20) into the mold, and then placed the part into an over to accelerate the curing process.

Board of the design process from trying different durometers of polyurethane, bearing hubs, and finally a difference in shape which brings us to the GG V2.

Some of the differences between V1 (Top Left) to V2 (Center and Center Bottom)
V2 compared to V1 is slimmer, has a lower center tooth wall for a concave shape, and a wider bearing flat bearing hub compared to the toothed thin bearing hub on V1.

Photo of our wheels on our grippers

Please send your questions if you have any!

Cad Files:
https://www.printables.com/model/475417-moldable-gripper-wheels

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Great work.
I’d love to know what may have been a surprise, or came easier or harder than expected in the process.

Side note - 7272 at the nyc regional had molded wheels and when I asked about it, they mentioned they were just trying to reuse resources they had. (Possibly they had made molded items in the past I forgot to ask)

We, 5090, made our own molded wheels last year out of silicone with 3d printed hubs. We went throught quite a few versions till we found ones that worked great. I’ll have to get some pics tomorrow at practice.

This year we molded silicone onto 3d printed grippers and they turned out great. We changed gripper designs during the season but it wasn’t due to the silicone. It’s pretty easy to do and not real expensive.


Only pic i have on my phone but will get so.e more tomorrow

The whole process wasn’t too hard, the designing of the wheels was just a few circles and some revolutes. The molding process was pretty straightforward. The hardest part of the whole process I’d say is extracting the part from the mold.

Something I was pretty surprised about was the durability of the wheels. The original V1 wheels were used during practice and Week 3 Muskegon and were only taken off of the robot for the V2 wheels which we used during Week 4 Troy, Week 6 MSC, and Week 8 Worlds.
I only replaced one wheel during this whole season, it was a V2 that had a break in the outside Onyx bearing hub that shattered from a gripper impact.

How much infill was the hub? Could it have been avoided with more infil or a different infil pattern?

It was 35% I believe. With some hindsight, it should have been 100%.

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