Barrel casting form for Projunk's Mecanum Wheel 82 mm

thingiverse

THIS IS WORK IN PROGRESS, I HAVE NOT CASTED ANY BARRELS YET. I have tried [projunk's parametric mecanum wheels](https://www.thingiverse.com/thing:641377), a great part for a robot that has worked well on the carpet but had issues on smooth surfaces. Now I've tried casting the barrels from very soft polyurethane (Shore A20) using this mold, thinking it will make the wheels more usable even with other materials. I have no prior experience in casting, so I'll be glad for any proposals to enhance the mold or process. You must use 3mm screws to tighten the mold parts together. Don't forget to insert axles into the mold before casting and use clay to protect axle bottom holes, otherwise material may leak. Use clay also around edges where two parts connect. It's necessary to make all 8 barrels at once with this form because some liquid material may leak into empty neighbor barrel cavities. The exact amount of material needed for 8 barrels is about ??? ml, which is enough to prepare ??? ml of material. I used a 20ml plastic syringe to fill it. I had to use a small piece of shrinkable tubing at the syringe needle hub to fill cavities easier. Fill each barrel slowly until liquid leaks from small air holes around. I haven't used any removal agent, so it was hard to open the mold and get barrels out without breaking the mold. Good luck! After removing barrels, cut excess material with a sharp knife. Don't try to rip it off. Print 1-layer washers and put them on the axle on each side of the barrel to prevent unwanted friction between barrel sides and wheel body.