Auto-retract threader - video

[BuffaloJohn]

Nice, but how does it work?

The tool holder has a sping loaded piston to drive the tool away from the work. There is a trip lever on the tool holder that will release the piston when the setup is in the desired position. The desired position is set by the screw device you can see at 0:30. That trip device in the earlier versions is higher and then he moves it so the trip is lower and it isn't as visible in the last versions.

Biggest issue will be regidity as to have a fast acting moveable tool holder, you have to have enouigh slop for the tool to move. If the force is always cutting in the same direction, you can be assured that the play will be consistant.