A few more sample jigs for my demo this weekend.
These jigs both thread onto the lathe. The one on the left threads directly onto the spindle (1 1/4" X 8 TPI in my case) I only threaded part way through this blank to make it "closed ended" as the drive portion in this case is the same diameter as the spindle. The tailstock adapter was threaded and turned the other night. The shoulder on the end was turned down to the same 1 1/4" diameter as the blank on the headstock.
These centers can be used to drive peppermill blanks, kaleidescope blanks, and similar objects. The shoulders on each end are really to center the piece, the drive actually comes from the pressure between both ends. The other advantage to using wood for the drive centers is that not only can they be custom fitted for a particular diameter but you can also turn right down and into the jig without damaging your tools.
The inside was removed and the jig can now be used to drive spheres and help center and drive hollow forms.