Built a hammerform for making long straight bends in aluminum sheet.
I used this form to bend a strip of 0.032" 2024-T3 Aluminum into a 3/4" channel to reinforce the lower access panel of the boot cowl. The strip was 1-11/16" wide and 16" long. I bent two 1/2" legs on this to make a channel 3/4" wide and 1/2" deep. This will be used to place nut-plates in to make a rigid connection along the edge of the boot cowl where the side panel screws to the lower access panel.
The piece was bent by clamping it onto the hammerform along the edge of the workbench with bar clamps. The strip was aligned with a setback mark on the form, which has a 1/8" radius (via a router bit) - the mark is 1/8" from the edge. The mark on the strip was made by adding the bend allowance to the leg length to get a sight line, just like you would do for bending in a regualr brake. This was all calculated using standard bending formulas for using sheetmetal brakes. The first leg was bent down using a rubber mallet, and finishing with a body hammer. The second was done by clamping the second leg in form and bending the back with the first leg out. The form was 3/4" thick so the leg just wrapped underneath. I used a 10 degree relief on the lower edge of the form to allow for springback. It came out pretty well I think.
