Daniel and Hector installing motors and mounts.
Hector, Daniel, and Daniel mounting motors.
Oscar relaxes in the background as legs are
trimmed for clearance.
56 SERVO 11.2009
sweat, maybe even a few tears along the way. Daniel
Aldama works for Outback Engineering and we had access
to their facilities to assist with the build. Essentially, that
gave us a drill press and a saw. We are actually like five
MacGyvers, so if we had enough time we probably would
have been able to make a space shuttle in there.
To keep production time as low as possible, we
designed all the legs to be identical. This allowed us to
make a simple cut list and set up a manufacturing line in
the machine shop. Measure, cut, center punch, drill, done.
This process went on for a couple days until we wiped the
sweat from our brow, took a sip from our donated Bawls
energy drinks (thanks Bawls!), and stepped back to admire
the piles of wood and steel that we had amassed. Daniel
welded the steel together and we hammered in our bronze
bearings. Before long, we had eight legs, ready to be
The frame itself is simply 2x4 boards attached to one
another with industrial strength wood glue and screws.
A two inch diameter oak dowel runs the length of the
machine underneath and serves as the main structural
element. Holes in the center of the horizontal frame
elements have one inch ID bronze bearings pressed in
that support the crankshaft. Along the outside of the
frame, there are two 5/8 inch stress-proof steel rods
secured with shaft collars that support the legs.
Locomotive power comes from two wheelchair motors,
purchased as part of a beat-up electric wheelchair from
Craigslist out of what appeared to be a burned down meth
lab. We didn’t ask questions because we got an entire
electric wheelchair out of it for only $100. The batteries
were shot, but the motors and control electronics appeared
to be in perfect working order.
The motors themselves, however, required the only
truly custom parts on the whole machine. The shaft was
an unusual metric double-D that required us to make a hub
adapter and secure it with four 1/4 inch setscrews. This
proved to be plenty strong. The crank shaft itself was
Daniel installing a leg pivot bolt.