As you know we are building Cadbike 31 for Aad. The CAD design is as good as finished, how to transform the sheetmetal parts from CAD to reality?

Actually the combination between CAD and sheetmetalwork is quite easy, I made a 3D CAD model of the fender with a "buck" and printed the 8 parts of the buck in full scale, Aad glued the prints on some 3/4" thick plywood and cut out the pieces with a bandsaw. I designed the pieces so they would slot together so in 30 minutes we had a buck.

Aad started by cutting an oversized piece of 3 mm aluminum. The aluminum was then annealed to make it softer. The center area is stretched by hitting it with a wooden hammer on a beater bag filled with birdshot. The edges of the sheet are shrunk with a little hand operated shrinker. The english wheel is set to slightly more than the material thickness and is only used to roll out the bumps and smooth the metal, not to stretch. As the shape gets closer to the buck Aad trims the edges of the fender closer to the final shape.

It is a job that requires patience but is great fun, just keep repeating the steps untill the metal fits the buck! To be continued....