We’ve all run into situations where the right part for the job isn’t something that you can just buy off the shelf. In a lot of cases, 3D-printing is the cure for that problem, but sometimes you need to go big with tough parts for a tough job. These custom molded urethane battlebot wheels are a great example of that. (Video, embedded below.)

The robotic warrior in question is “Copperhead”, a heavyweight death-dealer that has competed on the “BattleBots” show on TV. It’s an incredibly stout machine with a ridiculous 50 pound (23 kg) drum of spinning tool-steel on the front to disassemble competitors. Add to that the sheer mass of the bot’s armor plating and running gear, throw in the need to withstand the punishment meted out by equally diabolical weapons, and standard wheels are not going to fly.

As [Robert Cowan] details in the video below, nothing but the sturdiest wheels will do, so the bot builders mold custom wheels with integrated hubs. The four-piece mold was machined out of aluminum to hold the plastic hubs, which were also machined but could easily have been 3D-printed. Polyurethane resin is poured in and adheres to the plastic hub better than we’d have thought it would: enough so to avoid coming apart despite some pretty severe blows. The whole casting process is a good watch, as is the overview of Copperhead’s design. And watching it tear apart “War Hawk” was a treat too.

You may not be building battle bots, but a scaled-down version of this process could be a handy trick to have stored away for someday.

Thanks for the tip, [Zane Atkins].