These can be used on the lathe in either a 3 jaw or 4 jaw chuck. I like using them in the 4 jaw since I can set them up to run true.
Rod connectors are available in just about any home store or hardware store and come in many different threads so many times you
can use them right off the shelf. Since they are threaded the full length you can insert a set screw from the back side to act
as a stop to get a predetermined length for the threaded rod or bolt you are working on.
I needed to make 6 brass knobs for a new project and wanted to use some flat head screws (1/4-20) for the threaded stud.
Easy, just cutoff the head at the right length, loctite the stud to the threaded brass knurled knob and let it set up.
Next day I cleaned them up in the lathe as shown.
One note, don't countersink the holes in the knobs. It will just require taking more material from the face of the knob to clean it up.
Project for these is still in the shop but should be done soon.