Indexing plate from brake disc rotor

I made an indexing back plate for my three jaw. It also provides a "true" centering function so I can do work that needs the centering to be dialed in, like a four jaw. But I did not think of providing multiple hole circles. I only made one hole circle with 60 holes. I plan, some day, to make Vernier style shoes (like the common spin indexers use) for it so I can subdivide those 60 divisions into numbers like 360, 600, 720, and perhaps some odd numbers like 7 x 60 = 420 or 11 x 60 = 660.

I have used this indexing on my lathe chuck several times along with some milling attachments for the lathe to allow me to do some jobs completely in the lathe. It is neat to be able to turn a diameter and then, without taking it out of the lathe, add a hex or five sided area on that part that is going to be perfectly centered.

Indexing plate from brake disc rotor - video