This is the second Instructable in my maybe series of "Shop cheats." And a link to the first if you missed it: here.
I will not take credit for this one, as I saw it in a newsletter for "The Home Shop Machinist." Every now and again one seems to need to turn a bolt or other threaded work piece. But usually one does not want to damage or mar the threads when one chucks it up in the lathe. And usually making a custom arbor is a pain. Or one might try to lock the threads with two nuts (double nutted.) Only to have them be unevenly held by one's chuck, or slip loose while one attempts to turn the piece. I have been guilty of this on several occasions. So for a quick and dirty threaded arbor just take a nut, one that fits on your threaded work piece, and cut a slit in one side. Just use a hacksaw or band-saw. You may even be able to get away with using a cut-off wheel while it is on a bolt. You may want to clean the threads of the nut a bit as there probably will be some burs in them. Nothing a tap or slotted bolt cannot fix though. This way when using a three jaw chuck there is relief in the nut and it snugs up tight on the work piece. It works well. Almost too well. And they are completely reusable. I have begun to collect a number of slitted nuts just because I know I will be using them again.