As an industrial automation/controls engineer who just got into a sewing project, let me just echo that old (and new) sewing machines are industrial-technologic

As an industrial automation/controls engineer who just got into a sewing project, let me just echo that old (and new) sewing machines are industrial-technological miracles. And they were built long before servomotors and semiconductors were a thing. Even after watching it work, I'm still incredulous that a combination of castings and camshafts can do 4000 stitches per minute; if you asked me to tie a knot with a strand of thread with my normal modern tools of 6-axis robots and PLCs you'd be looking at a quarter million dollar machine that was two orders of magnitude slower than the Juki I'm used to. It is unusual for sewing machines that these examples require what they do. But it is also unusual as compared to other technology that your 100-year-old machine is so hyper-optimized, understandable, maintainable, and open that it doesn't require any reverse-engineering or external hardware.