If you really like someone and want to show them how special they are to you, one thing you can do is design and build them their very own mini strandbeest. You can buy these commercially through shapeways, kickstarter and think geek , but it just didn’t seem like the kind of thing worth giving unless I had poured a little of myself into it.
I figured some people might want to see the details of how I did this, so here they are.
I started by investigating how the legs worked. The inventor of the Strandbeest, Theo Jansen, created these legs based on a parallelogram, that when connected to a rotating driveshaft, will produce a walking motion, assuming everything is measured very precisely.
Basing everything on these measurements, I came up with the lengths I needed in inches, and drew out a to-scale plan for the legs. I transferred the to-scale measurements to pieces of thick plastic underneath my drawing paper using a set of pins, and then cut the plastic to make a stencil that I could use to draw guides on the wood that I would be cutting.
Using a power miter saw and a Japanese pull saw, I cut the triangles for the legs and linkages, respectively. I decided to use Bolivian Rosewood because I had read that it was good for making small puzzle pieces. I highly recommend Bolivian Rosewood if you have a project that requires accurate cuts to thin slices of wood. It’s hard, but still very easy to work with, and even though twenty of the linkages required 1/16″ thin slices that extended 3/4″, not one of them broke while I cut them with the pull saw.
I was surprised at how many parts this project required, each of which required much sculpting and refining. Each of the ten legs required ten different pieces of wood, so there are a hundred pieces of wood just in the legs. Counting the frame, driveshaft, and axel pins, there are about 180 parts total, most of which move independently of the others during operation.
The biggest unknown during the design and construction of this project was the driveshaft. This part is crucial as it coordinates and powers the motion of all the legs. I initially planned on using heat, muscle, and a wire bender to put 20 very accurate bends into a 3/16″ stainless steel rod. After a couple of bends, it became apparent that the precision required for success was much higher than what I would be able to pull off in my kitchen-turned-workshop.
After consulting a gunsmith at Weapons Specialists, LTD in SOHO and getting a $600 quote, I decided to go with plan-B, which was to build the driveshaft out of a combination of wood and metal. Aside from precision, the driveshaft needs to handle a lot of torque since it’s driving every leg. My savior for this part of the project was JB weld.
A consequence of the wood / metal driveshaft was that I couldn’t stick with my original plan to thread the driveshaft through each leg, due to the bulkier wood parts. Instead the driveshaft would be assembled in sections and stacked with the rest of the pieces during assembly. I opted not to fuse the driveshaft sections together since this would make disassembly nearly impossible. I suspect that this has some effect on the overall friction during operation, and might be why it does not walk freely, which was one of the initial goals of the project.
I finished it by dipping the feet in a custom green shade of plasti dip for added traction on smooth surfaces. All in all, it was a fun project and I got a lot of satisfaction out of designing something and seeing it through to completion, and I’m pretty sure that she loved it as a gift :)
I would like to refine the design a bit and eliminate enough friction points so it can walk with just a push. I suspect that this would require some re-engineering of the driveshaft. For now, the way it works is by cranking it on both ends and manually walking it along a surface. You can see it in action by playing the video below.