flamming deal alert- building sheet metal brake

[Frank]

Whenever I bend something small like stiffeners, attach angles or test pieces for the spar, the bend is effortless and the bend radius is perfect without any bowing. It's when I bend an 8 ft long piece of .032 that the resistance of the aluminum starts to overpower my diy brake. So, again, test on a big long piece.

And the more I think about it the more I think it is unrealistic to expect the bend radius to match the bending edge.

But yeah concentrating the force close to the bend intuitively makes sense.

[fairchild1934]

Frank--- here is the hinge I found. from a company called "Guden".

https://www.guden.com/Item/Heavy-Duty-Continuous-Hinges/PS10090811-72

This is a plain steel hinge- 6 feet long (use two) 2 inch wide flanges, 1/8 thick---3/8 steel pin--- 73$ each.

Do you think that would be strong enough not to "give" ?

as a possible mod to the hold down piece--- to create additional down force on the work--- I was thinking of running an angled piece of steel across the top with either coupling nuts to form an expandable "jack" or even using a couple of small hydraulic bottle jacks so I could slide in the work- tighten the hold down bolts at the end then pump up the jacks to push down the center. Dont see where anyone has tried that. Looks like the commercial made brakes just use a jack screw to create a slight outward bow to the hold down bar to create extra tension in the center. But the only hinge they have is at the ends. ( a few inches long--- and they depend on the rigidity of a huge heavy, thick hold down and the bridge straps )


Tim

[Frank]

Tim, I could be wrong, but it looks like overkill to me, in terms of size. And underkill in terms of material if it's not stainless steel. I think you should use a stainless steel hinge with pre-drilled holes. You don't want to have to drill all those mounting holes through stainless steel.