Good score Rudy. That is a very neat design. He is right, there are other retracting mechanisms, but none that I've seen with that amount of retraction reach to clear shoulders like his demo video + simplicity of resetting tool position. I don't 100% understand the interaction geometry of the parts. Reminds me of a Winchester lever loader which I don't fully understand either LOL. Maybe I could reach out to him & even get some sketches, from that load into my CAD program & do the similar motion evaluation.
I scratched my head over this thread retraction issue in the past & never really resolved, leaving it to:
1. run threading tool in opposite direction (from HS to TS). Not all lathes have the Fwd/Rev & feed screw direction capability and/or screw spindle vs Camlock. Fortunately mine does.
2. have the retraction occur with solenoid, either directly to the plunger movement itself, or un-triggering a lock & allowing a spring to move. (I think that's mechanically what he achieved).
3. installing a mini dedicated geared motor on the end of the lathe spindle that basically drives the threading operation. The main motor is turned off & is just rotating along for the ride. A glorified way of powering the 'hand crank' method but now you have some power behind it & potential to limit stop electrically
2&3 are above my electrical pay grade so they sit in cobweb mode.
I'm game to work on this if you are!!