For Mini Lathe and Micro Lathe three jaw chucks. 1/4″ thick acrylic, three strong 6mm Neodymium magnets. Makes aligning a spacer that needs to be turned much easier. Allows small and short parts to project past the chuck jaws, and not fall inside the bore.
These are inexpensive, if you need a thicker 1/2″ spacer these can be stacked. If you are going for 0.0001″, a dial indicator and four independent jaw chuck are necessary. But if you are wanting to size something for a chair leg, this is your tool!
If your chuck has a grease fitting inline with one of the chuck stop arms, you will need to relieve the arm.