I tried doing the bend on the replacement drive horn, this time using the factory-approved method using a V-block, round form (I used a pipe), and an arbor press (which I picked up for $44 + shipping from Harbor Freight).
The results were the same. As can be seen in pic 1, the actual bend (dotted line) moved "downhill" along the angled edge at the top. I can only conclude that the aysmmetric loading cause by the thinner material "downhill" on the angled edge is causing the bend to take the path of least resistance and bend where the material is thinner.
Sonex factory support believes the V in my block is too wide, and thus the material bends too far from the desired line. I had thought of that, and made a narrower V block and tried that with similar results. If I make the V any narrower it is too narrow for me to work the press due to the force required, and I'm not a weak man...
I'm going to talk to the folks at my EAA chapter meeting tomorrow and see if they have any suggestions.
