After much research on the VAF website, I bought a set of the Buller dies to help bend the longerons. I carefully measured and marked the longerons as indicated in the plans with forward, aft, inside, outside, left and right. I also put marks at 1 inch increments in the gradual bend area. Kevin and I set up the dies as indicated in the instructions, for a test run on some extra angle. We put electrical tape on the outside face and greased the inside face. We clamped the dies in the vise and did some test bends which came out well. Then we double checked all measurements and set up the actual longeron the same way.
On the first longeron we spent a lot of time trying to get the curve to match the F-721B right from the start. We would clamp and check and move the longeron and reclamp and rebend . Decided we were working too much at the beginning of the bend, and so decided to run the whole bend area through the dies and see where we were. We compared the results to the full size template and the F-721 and had overbent somewhat. It was easy for the two of us to un-bend slightly and get the curve to match the template and F-721 well within tolerance.
The second longeron went much faster as we made one pass at 1 inch increments and found the bend too shallow, went back for another pass and were overbent as with the first one. Un-bent the longeron and matched the F-721 and template.
