Machine Design

Bearings Make for a Killer Bot

Who would have thought something as ordinary as a bearing could spark a person’s imagination? DualVee bearings from Bishop-Wisecarver Corp., Pittsburg, Calif., did exactly that for Jamie Hyneman when he was building a fighting robot. This was long before he became a TV personality on the show MythBusters. He says designing the robot started with an idea and the imaginative use of pieces and parts.

The bearing’s elegant design and unusual grooved edge really caught his eye, according to Hyneman. He put the bearings to work in “Blendo,” a fighting robot that used centrifugal force to conquer opponents. Basing his design on an inertial weapon concept, he built the robot with a lawnmower engine and a Chinese wok.

Hyneman added stubby blades to the wok’s exterior, and bolted the whole thing to a steel ring that formed Blendo’s perimeter. He then mounted 12 DualVee bearings to the robot’s beveled chassis edge. The bearings kept the spinning mass centered on the chassis and let it withstand impacts.

”To accomplish the same thing with normal bearings would have required a more-complex design,” says Hyneman. “I would have had to have two bearings perched at an angle, which would have been complicated from a mounting point of view. In this case, all I had to do was give the grooved bearings a vertical axis and mount them on a circular flywheel. It was a simple and robust design.”

The exterior spun at 500 rpm, powering Blendo’s sinister spin and blades that sliced through the competition at 80 mph. Blendo’s exterior and blades worked as the robot’s armor and weapon — the only way to hurt it was to hammer, penetrate, or flip it over.

Easier said than done, says Hyneman. Blendo’s opponents at San Francisco’s Robot Wars and Comedy Central’s BattleBots quickly learned that hitting a spinning object means your weapon is going to fly and then crash to pieces. Battles with Blendo ended in mere seconds. Hyneman’s robot was eventually ruled so dangerous and unstoppable that event organizers banned it from the scene.

Bishop-Wisecarver Corp.,

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