Marc spent some time looking for an inexpensive Bending Brake when he ran across a set of free plans from Dave Clay.  http://www.ch601.org/tools/bendbrake/brakeplans.pdf

Dave Clay’s Bending Brake. Photo is from Dave’s website.

Marc built the brake and shared his experience. He reports:

It does work well, but the I find the radius a little to large, I will make another top part once it has been machined square so I can reduce the radius. The standard angle iron edge does not give a tighter radius no matter how I filled it.

I used a smaller angle (2-inch x 2-inch x 0.650-inch) than what is called for in the plans but as I see it one can use what suits your needs.

I mounted mine on a section of square tubing (3-inch x 3-inch x 0.060-inch x same length as bending brake) with a angle welded to it for clamping the vice, the total length of the one I made is 47.5-inches.

The piano hinge remained the same except that I used 3/16 AD airplane rivets instead of steel pop rivets and doubled up on the rivets using a 1.250-inch rivet pitch.The adjustable top part (adjustable with slots to change the set back when bending) I made with slots cut into like the real thing would have (okay the real one has removable sections that look like teeth) but cut slots work just fine as well.

Please see attached jpeg of my version of this, called the “Marc 1 Field Bending Brake”.

The brake will work well if treated properly and not pushed by bending material that is to thick or to hard. I have bent 0.020-inch mild steel, 0.040-inch mild steel, 0.060-inch mild steel and some 0.40-inch T3 Alclad Aluminium.

I certainly would not go above 0.080-inch mild steel with the “Marc 1”.
The only weak point as see it is the piano hinge, the rest is put up with use.

Here are photos of Marc’s finished brake: