I was interested in making a machine similar to one of Theo Jansen's Strandbeest machines. I soon found one called Brabeast here on Thingiverse and started to work on printing and building it. However the usual wind driven fan mechanism never looked promising. The teeth of the planetary gear were too small and I knew this would mean they'd have fine tolerances and probably wouldn't work well in 3D printed form. I also figured I'd need a hurricane to make the machine walk. So I worked on making an electric motor driven Brabeast.
The final result is essentially just the original Brabeast by Gyrobot combined with the oversized crank sections of Vivifyer. However I have redesigned the crankshaft parts slightly so they fit together better, and I also added three new parts - a motor mount on each end of the Brabeast, and a "cargo deck", so the Brabeast can carry some small items such as the battery compartment. I used geared motors with a 10rpm output shaft so that the Brabeast walks slowly and the motors can produce enough torque. I chose 3 volt motors to reduce battery size, and also in the hope that perhaps the device can be run off a small solar panel. I put a motor on each end of the Brabeast because one motor did not have sufficient torque to turn the crankshaft, and because a motor on each end allows the Brabeast to be balanced and not fall over.
This is the motor and battery compartment I used:
I have only made a six segment version so far but it works just fine. It can be made to walk faster by using faster RPM geared motors. Some lubrication of the joints also helps the machine work better.
To 3D print the Brabeast, print one segment at a time. Each segment requires two prints of "PLATE_LEG_SECTION_more compact", and one print of "CRANK_SHAFT_and_ARM_Dave". Use the "BRABEAST_LEG_SECTION" file to help you assemble each segment, and then the "BRABEAST" file to assemble the segments into a Brabeast. Use superglue to connect the cranks to each other, being careful not to get glue on other parts of the mechanism.
To mount the motors requires drilling holes in the crank ends to fit the motor shafts. Use epoxy to glue the shafts into the crank, and attach the motors to the motor mounts using M3 or similar screws. Th cargo desk is simply glued on top of the motor mounts.
The files also include a drill adapter so you can hook up the Brabeast to a drill motor and test it out and give it some wear in time. The legs can move very fast given the chance!
You can use the Split function of free Slic3r software to split up the PLATE_LEG_SECTION and others into separate parts if you don't have a print bed large enough to print it as a single print.
Possibly you might also want to scale the leg pins to 85% of their normal length so the fit is tighter. That's up to you. Drilling out the holes of the crossbeam may also be necessary. I will probably not be continuing development of this particular walker design, so you're on your own for changes from here, but it's very easy to redesign parts using OpenSCAD.
I have included the OpenSCAD files of the motor mounts, cargo deck, and cranks, in case you need to modify them for different motors, etc.
I am currently working on a 200% scale version of this same Brabeast, and it is more developed than this one, has tighter tolerances and fit, and larger motors and battery. I will post it here to Thingiverse once I'm finished.