A small variation on Wiley's approach:
A long time back I made templates out of phenolic sheet for the radii that I commonly use (3" for scrubs, 6", 12", 20"). The templates have registration features for the iron widths that I use each of them on.
When I want to shape an iron I paint its back with Dykem, position the template, and then scribe the desired leading edge with an awl.
I grind the leading edge to the scribed line, with the wheel at 90 deg to the iron. I then finally grind the primary bevel to whatever angle I want.
Grinding the camber profile first minimizes the degree to which I have to work adjacent to a thin edge when establishing the bevel.