That is a terrific idea. I just got a Kalamazoo belt grinder, so I need this. Nice work, and man, you could sure use a DoAll vertical bandsaw.I just made one of these for my new belt grinder. See it work at 12:55
The radius is easily adjusted in his design.First it would help if we had an idea of size of the radius. Makes a big difference in making the part.
Stupotty has the answer I would propose if you don't have a rotary table. You put a pin in and turn around it. I would add a longer handle to control the piece being cut. It works well.