Here are my alterations. A notched block of oak with 10mm bar set to receive the dropout securely clamped to the pipe bender and a token strip of leather to protect the face of the fork blade.
The fork blades were filled with soapy water, taped up and left overnight in the deep freeze. With one of us holding the far end of the blade in grips, ready to sense and counter any twist as the blade was bent, we started with a small deflection. So far so good. More. Eek! Considerable failure.
So, the up shot? The mandrel was too wide, the radius of bend too small and the thuggish bike builder eats lesson pie. I really haven’t the time to start again and build a proper fork bending jig so I’m back to the man who sells pipes for a pair of pre bent blades and another set of dropouts. It would appear that corners cannot be cut.