Fabricating Symetrical Brackets

[jcoyier]

I need to replicate some brackets in a repair project and would like to get some ideas on how to do it. The first problem I encounter is once the planar shape has be cut out of 20 gauge ss it needs to be drilled on both ends to accomodate an AN3 bolt that will have to align nicely through these two holes once wrapped around a forming mandrel that will allow a snug fit onto a 1.0 inch strut or spar. If the wrap isn't exactly centered and square, the final hole locations will not allow the bolt to align square to the bracket plane. If I had a mill I could maybe pull this off. I have a drill press with a mediocre X/Y vise. (yes, I am looking through this forum...I am currently on page 32, nothing I could find yet). The photo attachment shows one of these brackets installed on the 1.0 inch trailing edge spar. The nut end involves a 10-32 rivnut that needs to line up with the 3/16 hole on the bolt head end.

[DaleB]

Cut the part out, form to shape, put a block of wood in the middle and drill the hole in a drill press.

[Dana]

Hard to understand from your picture and description exactly what you're trying to accomplish, got a sketch? But it does sound like you need to drill the hole(s) after forming.

[jcoyier]

Here are two more photos that might help with my poor description;
59115912

The hole with the bolt must line up. Of course, I want the result to be perfectly symmetrical after it's been formed to fit unto a 1.0 inch tube (spar or strut).

[Dana]

Gotcha. Do what Dale said, form it first, clamp it over a block, and drill afterwards.

[jcoyier]

If I don't maintain exactly square alignment during forming (right along the mirror image axis) the "ears" of the bracket will end up misaligned even if I drill the through hole while clamped on a block. So I guess my question resolves down to how to form a bracket like this so that the "ears" end up exactly aligned. If I find an easy, consistent way to do this then using the idea of drilling after forming will be an easy last step.

[DaleB]

Either bend, adjust the two sides to suit, then drill, or just start with a rectangular piece to begin with. Bend, insert wood block, trim with band saw and drill on a press.