I am relieved in a way that people more informed than I are unable to fathom out how the Duprat cranks were made. I too looked at an unplated pair expecting to find joints but found none. Presumably the slot across the crank end started life as a hole large enough to allow a drill down and was reforged to final shape. As I am of Cornish blood, I choose to believe that it was forged by Breton piskies or nockers. All the same, I would welcome a more rational explanation. Stuart Tallack in springtime Sussex