Hairspring Stud Vise

This is a handy and hard to find tool for holding hairsprings for work.

I used it here to move the stud a little.  The outside end of the spring passes through a hole in the stud.  A brass pin follows and is driven friction tight.  The pin can be removed to adjust the stud.

This is not a real common task, and a tool like this is not used often, but when the need does come up, there's nothing like having the right thing at hand.