Old Nova 35mm Spigot Jaws

[Michael Mills]

I have the set below without the dovetail on the exterior (sometime in the 90’s?). Current 35mm spigot jaws have a dovetail on the outside. Instructions mention a small step and large step and I assume they are for boxes or enclosed forms. I can follow the small step since the top of a box can be registered against the top of the large step for alignment.
I see no way to align an item on the large step other than using the top of the chuck itself unless the recess is sufficiently long and straight to provide self alignment.
Anyone know of another possible use for these in expansion?

[John Keeton]

Michael, if your recess is not too deep, the front of the larger "step" should bottom out on the recess. Seems that would work in expansion mode. The dovetail certainly seems like it would be more secure!