I don't know about the exact angles, but I think a couple of degrees
would be enough.
But, I don't think you will be happy with the lower die being so big
(3 X 3). You only need a half inch or so of "vee". If you have much
more, you will have trouble keeping things centered as the upper die
descends and you will be bending the work all the way from the edges 1
1/2" away from the center. So, I think you'd see a curving bend either
side of the desired bend.

I am no expert at this, but check out my solution at:

http://www.spaco.org/Press.htm

You can see one of my brakes on the floor in a couple of pix. I used
90 degrees on both dies because 1.) the upper die is just a piece of 1
1/2" Sq and the bottom die was milled with an endmill.

By the way, my brakes are all mild steel. That works okay, but if I am
bending narrow thick things, I can dent and scratch the lower die. If I
did it again, I'd sure use tool steel, probably 4140.

Actually, for the first brake I made, I used a piece of 1" square mild
steel for the upper die and I just welded 2 quarter inch thick plates
side by side to a bigger plate, leaving a 1/2" gap between them. It
worked quite well. Shallower is better!!!

Pete Stanaitis
------------------------------

wrote:

I am working on a simplified version of Northern Tools brake press:
http://www2.northerntool.com/metal-f...tem-145531.htm

With the lower die at 90 degrees (I am using a piece of scrap angle,
3x3x0.5 wall), I presume the upper die should be less than 90 deg.
Correct? I am thinking of about 80 degree angle. Your thoughts?

My brake press will have a 11.25 length working surface (mainly
because the piece of 1x4 CRS scrap that I have is 11.25 long) and at
this time I am going to try to make it work without the two guide
posts.