Spar web forming

[fairchild1934]

Hello David----- I accidently found 5 lengths of 1/4 inch thick 3 inch wide angle iron at -- of all places- Lowes.
I was thinking of using a 3/8 pin stainless steel piano hinge. (there is a company on the web that does just continious hinges)
that way I wouldnt have an unsupported run in the center where it would have to rely on the angle to not deflect.

It looks like in your picture it is designed to have the sheet metal inboard of the hinges only. Will using a continious hinge
prevent the two angles from coming close enough together to bend a tight enough bend line ? seems like the "knuckles" on
the piano hinge would occupy the space where you want the bend to be-----------

Tim

[David Dagenais]

Hello Tim,
That is actually the reason that I opted not to use a piano hinge in building a break. I have seen others who just used a hefty hinge on either end of the angle but in doing so, the hinged angle needs to be beefed up so that it will not tend to bow in the middle. My approach was to weld a 1/4 inch thick x 1.5 inch angle on the inside of the 4 inch angle and that appears to have strengthened it sufficiently with no bowing noticed so far. I did a bend of three different pieces in the left middle and right ends and they all had the same radius of bend.
Let me know if you have any questions.
David