I suspect the elevator trim tab is probably the #1 open stock purchase from Van's. I made a total of 4 attempts on my elevator trim tab. And, I finally just accepted #4, even though it wasn't perfect.
Using the form block inside the trim tab, wedged into the V jig didn't work for me. The whole thing kept moving no matter how much I tried to wedge and clamp. One thing I concluded is that the size and shape of the form block isn't as critical as securing the form block to the work piece and both to a solid surface so that it doesn't move. And, the bend line must be as accurate as possible.
I used my heavy steel backriveting plate to form the tab bend lines. I secured the trim tab under the steel plate with a couple of C-clamps on the edge of my work bench. And, I took my time in aligning the steel plate precisely to the bend line I marked on the trim tab with a fine point sharpie.
Then, I started the bend by hand, just pushing with my fingers until it was bent enough to work a 1 inch block (just a piece of wood from the scrap pile) under the edge. I then used the wood block and a mallet to finish the bend.
Mount Vernon, WA
2020 VAF Supporter