Servo - November 2015

SERVO 11.2015 23

spur gear on the motor were engaging the planet gears in the gearbox. This overloaded the teeth, and they deformed on both the motor (Figure 3) and the first stage in the gearbox until it locked up. One of the planet gears can be seen in Figure 4 next to an undamaged tooth. I dismantled the rest of the gearbox but there was no further impairment.

This damage would have sent most gearboxes into the trash can or the spare pile, but there is a big advantage in using the BaneBots P60 ( www.banebots.com). You can get replacements for all the various parts. The motor would go in the trash but I already had a replacement for it (Figure 5), so all I needed was four new planet gears (less than $8 total plus shipping, saving a lot over the $50+ for a complete new unit).

While I was waiting for those to arrive, I made sure the tabs on the new motor and the other undamaged one were fully formed (Figure 6) by bending them over using a flat bladed screwdriver and a few taps with a hammer. This should do the trick, but one could also add a bead of epoxy adhesive around the lip of the end plate to make this failure really unlikely in the future.

When the new gears arrived, I cleaned all the parts and reassembled it with fresh grease (Figure

7). This is messy, but not difficult; just note carefully what gear goes where as you take it apart. The motor mounting plate was removed from the old motor and fitted to the new motor. It (and then the motor) and gearbox were attached together with the four long screws to complete the assembly. I now had two good units (Figure 8) to go back into Isotelus. This is where the plans changed. I had been testing some HobbyKing 45A brushless ESCs (electronic speed controllers) to see how well they worked — both for powering weapons but also for driving the wheels of a 12 or 30 lb bot. I had built a test chassis using a couple of 2848 Tacon brushless motors with Figure 2. Damage to motor.