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Posted for JIMRHER@aol.com:
I built my complete panel for my 4P out of Aluminum and used several stiffeners in the back where the holes were big. I designed most of the stiffeners into the seams and I had the objective to not have any screws showing. Where I couldn't hide the screws I made "L" brackets for stiffeners that used the Instrument mounting screws and tied several instrument holes together, relieving the flange around the instrument. I got away without doing the bonding. I do use double sided tape to hold the stiffener in place when removing the instrument.
My background is in Sheetmetal and I tried many bonding types before and most fail sooner or later. In the specification sheet that Gerry provided you see a Big difference in the bond strength if the Al is Etched vs primed and that was my experience. Every good glue required Etching. Al oxidizes very fast so you need to bond it within 2 or 3 days to get full strength. However, I still found that the end of the bond would fail first and then the peal strength would be much lower. For a good bond most recommend a fastener at the end of the bond strip. That is why most bonds are spot welded or riveted, with the exception of the Yankee, American Traveler, aircraft and some military. But look up there bonding process and you won't want to do it.
Attached is my panel shot,
Jim Hergert
N6XE, "An Sex Y" L4P
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