I was thinking of bending the flap leading edge sheet metal pieces on the same 8' brake that I used for the spars but I had an idea for bending them myself. I made a brake out of 3/4" MDF. This actually worked better than I thought it would.
The flap leading edge material is .020 2024-T3 - I doubt the brake will bend anything much thicker than that. The first thing I did was cut 2 sheets sized 1’ x 8’ out of a 8' sheet of .020 2024-T3 using the router cutting method. Then I deburred the edges.
I then measured and marked the bend locations on the metal sheet. I then bent the angles in the aluminum sheet using the 8’ MDF brake.
Here’s the recipe for the MDF bending brake:: 2 sheets MDF - ¾” x 4x8 (47”x97”) 2 - 4’ piano hinges 1 – 2x6 straight with no twist Box of coarse thread drywall screws (I used 1-5/8”)
Step 1: Cut the 2 sheets MDF in half length wise. Mount the piano hinges on one edge and attach the other half to the hinge for make the bed and bending arm. On the side of the hinge that mounts to the MDF factory edge use drywall coarse screws for better grip.
Step 2: Use a router (or sander) to radius the edge of one of the other pieces to use as the bending edge. Attach a 2x6 flat on the opposite side of the radius a couple inches back from the working side and attach the other half sheet on edge to make a straight edge truss. (Note: I later discovered that the truss was not enough to prevent push up in the middle so I used a brace off the ceiling to hold it tight in the middle. I later removed the truss completely and added another brace which worked fine too.)
Step 3: Lay the bed and bending arm portion on your work bench. Set the other part on top. Position the sheet metal between the top and bottom and clamp at ends and brace in middle. To keep the top from slipping back you will need to screw the top and bottom together at the back with a couple drywall screws.
