Vintage Singer electric sewing machine conversion to Singer (or reproduction) hand crank.

Following on from this previous post I have been doing some work on some 3D printed prototypes. The pictures below are of prototype 3, meant to be a proof of  concept. As I made a bit of a booboo with the profile of the dish of the balance wheel, the adapter does not go far enough into the wheel, so it stands proud by a few millimetres. I also appeared to have messed up the grip of the boss. In the spirit of Rapid Iterative Development, I have a better profiled version almost ready to go, so after a good session of measuring and thinking, I will submit it for printing soon. I might wait for prototypes 2 and 2a to arrive from the UK to check out some other dimensions and parameters first.

The material used is PLA, which is a hard, biodegradeable plastic. The parts are very light, and I thought they might be fragile, but they actually feel quite good