I was just looking at the Dovo U-Tube video showing production symmetrical hollow grinding using a double wheel grinder. It was showing someone grinding straight spine razors and by keeping the spine flat on the tool rest, the edges would be straight also. No surprise there.

But if you have a curved spine keeping the spine on the rest would produce a matching curved (smiling) edge. How would you get a curved spine and a straight edge? Would you need 'large' wheels to establish the curve of the underside of the spine and then 'small' wheels and a tool rest long enough for both ends of the spine to rest on it to make a second grind straight across?

Just wondering.