Impressive Twisted Steel Hex Shaft During Software Testing

Just sharing some pretty impressive twisting of our steel 1/2” hex shaft that our MAXPlanetary and NEO motor managed to help create after some software testing gone wrong commanded our arm past its hard stop. Whoops.


What’s the ratio in that MAXPlanetary gearbox?


it’s within Rev’s torque limit testing/spec, okay?? Lol

50% max motor output limit

Note: original design called for 100:1 with a 3:1 reduction to the arm with a dead axle but did a recent redesign due to the mounting plates bending and causing the chain the skip a lot

Guessing 5-5-4-3:1? That’s… beefy. Getting a bit late in the season, but I’d highly recommend considering dropping that to ~100:1 and add a 3:1 chain reduction as well. This will help protect the gearbox/motor from any sudden shock loads as well.

Edit: just saw your edit… … :sweat_smile:

Lol you literally just described the original design but plate bending/chain skipping pushed it to this

This doesn’t surprise me too much, seeing as a few MaxPlanetaries ended up on REV’s BattleBot:


Any way to add support the shaft opposite the motor to reduce the bending? I assume the original design had the shaft cantilevered off that mounting plate?

Right, that was the first thought but the cantilevering was only the first of several problems. The motor was mounted to a 1/8” thick titanium plate with some structural bracketing, but the chain actually bent/deformed the arm axle itself (9” between bearings) and the entire titanium plate would warp, pulling our elevator bearing blocks with it and binding the elevator.

So the options in my mind were, redesign the entire plate to avoid the warping, add support structure on the gearbox output shaft to remove the cantilever, and redesign the arm to fit on a much shorter dead axle.
Or, try a direct drive, which was a bit faster thing to try. And then this happened :slight_smile:

What I’m really impressed with is that nothing else broke or twisted. That’s some mighty good construction.


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