Creating a functioning leg was the first part of fabrication. By this point a “working” 3D prototype existed out of plastic but it didn’t have much flexibility. It showed that this could work, not that it would work. For that we needed a full size leg. JP worked out the dimensions then together we worked on the fabrication. Most of the leg was put together with gorilla glue, 2 part epoxy and duct tape where it started to fall apart.
Another benefit of the wooden leg is it would allow us to visualize what the bike would look like with 3, 4, or 6 legs. It was at this point we settled on creating 4 legs. 4 legs seems like the bare minimum and 6 legs made the frame too big to fit on a sidewalk. Another bit of blind faith at this point was how the crankshaft would operate the 4 legs. By now all the measurements were made and in theory it would work.
Fabricating strandbeest legs in metal
Here is the beginning of fabricating a leg out of metal. This process was more or less an assembly line. The main components of each leg are triangles, joints, and connecting rods. Each leg is about ~30 pieces of metal.
Starting on the leg triangles
The process to cut each leg was basically:
- Measure a metal rod and cut each straight length using a drill press.
- Grind each end to fit firmly…some times required re cutting.
- Cut joints, typically 1″ or 2″ pieces from the 1/2″ metal rod.
- Fit each straight length on to a jig.
- Tack and weld joints to necessary straight lengths.
- Tack and weld each straight length to one another.
Moving on to connecting rods…
Connecting rods connect triangles to one another. These pieces needed to be sturdy. Each leg uses 2 connecting rods.