I don't see the spring-back as a big issue.
To do what you want, I simply mounted a 1 1/2" X 2" X 12" piece of mild
steel (for occassional use) or 4140 in 2 Vee blocks, at a 45 degree
angle in the vertical mill and took a cut that was 1/2" deep into the 2"
dimension. That's the bottom die.

Then I took a piece of 1 1/2" square stock, mounted it "on the diamond"
in vee blocks and machined a flat in the center of the 12" dimension,
wide enough to fit the upper die that came with my 20 ton press. I made
a duplicate of that upper die of mild steel, drilled and countersunk a
1/2" hole in that and attached it to a mating tapped hole in my new
upper die.
This has worked out VERY well for me. I have bent sheets up to about
..115 thick with this outfit. Don't go any deeper than 1/2" on the lower
die. That means that the sides of the Vee will be 1/2" X 0.707 or .3535
wide. You get crisper corners this way.

I keep thinking that I should design this thing to have a taller upper
die, but as long as I center the work under the jack, I don't have any
problems.

Pete Stanaitis


P.S. I added a 20 Ton air over hydraulic jack with an air operated
release to this press, and added foot controls. One for down and one
for up. Works slick and leaves both hands free to hold the work.
------------------------------------

Charles A. Sherwood wrote:

I would like to make an accessory for my 3 ton arbor press for bending
thin stock. Basically I need a V block and a wedge attached to the ram.
I have tried using a standard V block which works ok for messing around.

I think I need a V block that is actually a bit less than 90 degrees
so I can over bend enough to compensate for the spring back. So the
first question is how much less than 90? The second question is how
to make it? Cutting a 87 degree angle seems a bit tricky with a mill.
The only idea I can come up with it to rough it out with a bandsaw and
then use the shaper to cut the sides.

chuck