I'm learning to turn, and found this in a box of chucks and faceplates. The central hole isn't threaded but is recessed on the inside, so I thought it might be a type of mounting for a faceplate, or for a worm screw. I don't know what its for, please can somebody tell me?
I have s similar item which I have used as a one-screw faceplate. Not a lot to say about it, just put a screw through the hole and into a small piece of wood to turn a small bowl.