After some very limited success with powering the MountainBeest using windshield wiper motors and bicycle chain, I decided to try something else. ServoCity carries a line of motors that have up to 2995 oz-in (around 15 ft-lb) of torque. Although these high-torque motors are very slow (.5 RPM in the case mentioned), they seem like good candidates for being able to turn the legs consistently. The wiper motors were too fast anyway, so too slow didn’t seem too bad.
Check out the video below of me trying it out:
I originally settled on a 3 RPM motor, which is able to produce 1102 oz-in (around 5 ft-lb) of torque after estimating that this should be enough to turn the legs. It was, but just barely, as seen in the video. Unfortunately, after leaving a soldering iron on one of the motor terminals for too long, I managed to melt the plastic case. This means a few days setback while I get in a new motor to power the second leg.
On the bright side, I ordered two motors that run at 2 RPM and have a significantly higher torque rating at 1497 oz-in, or just under 8 ft-lb of torque. Hopefully this will keep the motors running smoothly, if not quickly. I also ordered some female crimp terminals, as I’d rather not make the mistake of burning through the motor housing again!
You might notice my wooden high-torque motor mounts in the first picture. These were made by drilling a hole slightly larger than the motor in question, then tapping through two sides for a 1/4 – 20 bolt. I then cut the top of the hole off as shown, then bolted it tightly down on the motor with a piece of soft rubberish stuff formerly lining my toolbox. It worked pretty well all things considered.