(05c) Finishing the Throat Sheet Forming
To begin forming, the male form is required as a backing plate to keep the copper blank flat while the inside flange is raised. The inside flange is slowly raised by first picking up the copper edge by tapping in a thin bladed screwdriver. Once a spot is raised I continued raising by tapping thin hardwood wedges under the copper, working them all around, followed by a thicker hardwood wedge. I anneal again at this point and switch to seasoned Oak sticks with mitered ends which are hammered all around to raise the flange further. (Photo 015) Gradually the flange is raised and the process is repeated until the flange is fully layed over. (Photo 016) To finish forming the barrel flange I.D. I used a short piece of 2"+ diam mild steel bar placed inside the open hole as a hammering "dolly" and working around the opening I snugged the copper tight to the former hole.
To complete forming this head the male former was turned over and the outside flange was hammered in the usual way, annealing as necessary, using the female former as a backing plate, until the flange was fully layed over. (Photo 017, 018, 019) The formers were then used as jigs to hold the head for machining and the overall result was excellent and exactly what I was trying for. (Photo 020)
PS - The final finish on the head pictured, as will be other copper surfaces, wasn't produced by pickling but by burnishing with a 3M Scotch-brite VF abrasive wheel.
