Jansen's Rhinoceros

    I've made a few other of Jansen's Strandbeests before, but my favorite was always the Rhinoceros and I've long wanted to make one of those. It's imposing and dramatic and has a very different feel than the majority of his other creations. After several starts and stops, I finally finished one.

    The leg mechanisms aren't difficult to make, but it was time consuming to get all the tolerances right for printing. And oh boy does it take a long time to assemble. Originally I designed the entire strandbeest as a single large assembly, but that was a nightmare to assemble so I went back to the drawing board to simplify. I changed the overall design so each pair of legs is a single module that can be assembled and adjusted and driven on its own. Each leg-pair is held together with a dozen press-fit 1mm steel shafts of various lengths. Then multiple leg-pair modules can be assembled together into a single strandbeest. Multiple modules just slide onto a pair of 3mm shafts, caps are press-fit onto the ends of those shafts, and then a 3mm driveshaft with press-fit drive gears pops into the top. Motor and batteries then pop into place at either end. The pop-in journal bearings that hold the driveshaft produce a lot of friction and every once in a while the driveshaft pops out of one of them, so I might put some more thought into that. But as is it walks just fine.

    It took me a while to find the right motor to power the thing. Each joint moves effortlessly, and each leg-pair moves very easily, but when you combine six modules together it takes quite a bit of torque to drive them. Eventually I found a really nice motor/gearbox with metal gears that drives at a fairly low speed and provides more than enough torque. I connected that to a 12V power supply and the rhinoceros could walk very smoothly. I couldn't find a 3S or 4S battery pack small enough for the rhinoceros, so I bought some 100mAh LiPo cells and soldered them together myself to make a 4S 100mAh pack. Everything works beautifully.

    As always, designs are posted on GrabCAD and Thingiverse. The motor I used is available from Amazon.