Thorp Air Command - T18.net

Anyone have a tip on how to bend the inside flange on the bulkheads without making them wavy.....especially in the corners where they are radiused?

Shorten the inside leg slightly Ryan where the radius is so you don't have a pile of material there to try to shrink, it doesn't take a half inch flange there to make it very rigid......Dan

Ryan
I don't know if this is a tip, I only seem to know the slow hard way of doing things but I managed to get moderately straight flanges by tightly clamping the bulkhead between 2 form blocks in a vice and then just bending the flanges over.
On the straight sections I used a wood block about the length of the straight section and just hit it with a heavy hammer until it was over about 45 degrees and then for the curves I used a rubber mallet to gently hit around the corner section.
Someone else will probably know an easier way to do this. I have also read of some builders bending the flanges over to 90
Also think most of the inside flanges are 3/8".
Actually does anyone know how much tolerance is allowable on these wavy flanges, on some older T18s the flanges on the frame behind the seats into baggage compartment get knocked around pretty badly?

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Stug

I think the key is what Stug suggested with two form blocks clamped tightly. You can bend the flange to 90 degrees easily. Just make sure you bend all of it at once. If you start on one side and work your way to the other, it will be wavy. Danny's suggestion of cutting out the corners helps too. I cut mine at 45 degrees. I learned a real trick at a Porterville fly in some years ago. Frank Roncelli, the master rib maker, taught me to use a lead slap as the final step to making the flange lie flat. It is a piece of lead about and inch wide, about 3/8 inch thick and about 1.5 ft long. It actually can shrink the al on the flange.
Incidentally, all flanges are 3/4 inch wide.
Cubes

those are good lookin bulkheads....I have a bunch of scrap made right now. Thanks for the tips.