Arthropoda

Several nights of frenetic sketching, modeling, and designing later, the legs have come together.  While there may yet be a few kinks to iron out (e.g. the effective transmission of torque from the wheel to the cranks), there is a definite shape to the thing, one which now only wants for a shell.

The previous iteration was an abomination of white plastic, an attempt to print everything in one go, and at twice the size of the current model.  The result was a terrible mess, as the 3-D printer had managed to take 11 hours to print the part, and the support raft had warped terribly, leaving the parts deformed.  Where there had been no deformation, I found that I had not anticipated the thickness of the plastic deposited, leaving the pins too large and the holes too small.

This run had its parts printed individually, with the pins speced out to radii of 1/4 mm less than the corresponding holes, which has worked marvelously, allowing the parts to join, and holding the parts together along the ridges formed by the plastic along the circumferences.  The individual parts are small, but the assembly fits comfortably in one's hand, and gives an idea of the final size - something fist-sized, yet light.