A creation like this MountainBeest “kinetic sculpture” is never really done, but at this point it’s at least ready to display. Here’s a video of it showing off the latest improvements, an onboard GoPro camera, and remote control of the legs.
This walking ‘Beest should be close to ready for it’s appearance at the Columbia Maker Faire on June 14th. They’ve told me there will be some sort of winch there to hoist it up and down, so it should be pretty cool. I’m glad I hooked it up at home so I would have all the rigging ready.
Hopefully it won’t fall apart and/or they make some sort of safety zone under the contraption when it’s under display. If you happen to be in the area that weekend, be sure to come say “hi” and gawk at this contraption. For the next best thing, follow the “read more” link for more videos of my progress, as well as some more descriptions and pictures.
Leg Remote Control Read more »
If you’re transmitting mechanical power via a piece of PVC pipe, chances are that things aren’t aligned perfectly. There’s also a good chance that your pipe transmits a certain amount of shock load, as seen in my Mountainbeest. In my ‘Beest’s case, there is a certain point as the motor turns that the driving shaft turns violently due to gravity.
After ruining a fairly expensive motor* due to this violent motion, and nearly losing another, it was time for a change. Check out the video (and other build info) after the “read more” to see how this improvised PVC beam coupler (AKA helical coupler) turned out. I’m quite happy with the results: Read more »
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.