Lathe Crank Handle

I frequently single-point-thread telescope and camera adapters with metric threads on my lathe. They usually only have a few full threads and doing the threading under power, especially up to a shoulder, doesn't work. For years I've just been rolling the lathe over by spinning the chuck with my hand. This is doable, but there's a better way. A crank handle fitted to the lathe spindle makes the job much easier and gives far better control. My crank handle is based entirely on a design in Projects in Metal, June 1989, by Harold Mason. I had to scale it up to fit my Emco-Maier Super 11, but the concept and function is all Harold's. The beauty of the design is it's simple use. Just insert in the lathe spindle and tighten the nut on the crank. This locks the handle at the desired radius and locks the handle in the spindle bore simultaneously.