Texas signmaker,
Using angle aluminum for returns on aluminum pans is how I was taught to do it at one large electric sign shop. This shop had three fulltime sheet metal fabricators, but they were kept busy doing more important jobs. They did not like to stop what they were doing to make a pan face. They showed me how to make pans so they would not need to do it.
They did not want me tying up the power brake, so I was instructed to use angle aluminum, 2-inch or 1-1/2-inch. I was also taught to make a notched-type corner rather than a 45-degree miter for the corners. They said it looked better. But I suspect they didn't want me to tie up the miter saw, either, but use the bandsaw instead. I could make pans all day long on a back table and I was in nobody's way.
My angle returns were always welded to the faces. I used a bench punch to poke a series of 3/8-inch holes along the length of the angle, on 8-inch centers or so, then after clamping the angle to the back of a face of .063" aluminum, I put a small weld in each hole. Pans can be made very quickly this way once you get the hang of welding .063" without burning through, and the returns are strong for a solid installation if you hang the sign from the top and bottom returns. And this allows for no visible fasteners on the face.
VHB tape could have been used instead of welding, of course, but this shop did not like the slight gap. Lord adhesive would work, too, but there is clamp time. Welding is the quickest.
If you use ACM panels with angle aluminum returns you will have a black edge from the ACM. Is this why you would want to wrap the edges? You might find that the black edge is really not objectionable.
I was also taught to use angle aluminum returns to make pans with radius corners. You simply cut the angle short of the radius and wrap a piece of 2-inch .080" around the curve on the back side of the radius with small welds to the face spaced an inch or a little less apart.
It is easy to make odd-shaped pans this way, too, an impossibility with a brake.
My sketch shows a corner radius return tied to straight angle aluminum returns. I know it looks like a pain in the rear to fab a corner this way, but it's much quicker than you think when you do it a lot. And I don't know of any other way that is practical. Even if you have to do a little sanding around the corners to flush the edges nicely, it's still quick. And once painted it looks great.
Brad in Kansas City
