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

Find a place that sells brake dies. It is common to find drop in less than
12" lengths. I believe 87 is the angle of the 16 ga die I have.
Steve Peterson
"Charles A. Sherwood" wrote in message
...

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

Try a 90° block first. It won't take that long. Chuck the block up at 45°
and mill it with an end mill. Or if you don't have a tilting chuck then
slew the mill head 45° and chuck the part flat and mill it. That's the
way the brake on my ironworker is and it works fine. I have the little
Lee Valley vise brake (cute!) and it's cut to 90° and it works fine for
thin stuff too.

If that doesn't work out for you then you can always make the angle a
little steeper on your shaper.

Grant

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

You can make an air bending die in a few minutes: get 3 peices of
cold rolled rod about 4 times the dimeter of the stock, weld 2
peices to the flat of a piece of bar stock about 1-1/2 diameters
apart, the other rod to the edge of another bar, press away.

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

Charles A. Sherwood writes:

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.

Don't need to use a vee block. My commercial Handy-Bend HPB 120 uses
angles arranged thus (in ASCII art) in cross-section, base of the jack
on the top of the upper part:

-++-
||
--+ +--
| |
| |

Then the work goes in like this:

\ -++- /
\ || /
--+\__/+--
| |
| |

With this you just press enough to overcome spring-back, and you can do
more than 90 deg if need be.

Thanks for the ideas!!
I appreciate it.
I will try some of them out.

chuck

I remember trying this before. It does work, but I found that
the bends were not crisp. The unsupported area had a gentle bend
and there was a sharper bend directly under the wedge. It also
marked up the work a lot as the piece slid into the hole.


Don't need to use a vee block. My commercial Handy-Bend HPB 120 uses
angles arranged thus (in ASCII art) in cross-section, base of the jack
on the top of the upper part:

-++-
||
--+ +--
| |
| |

Then the work goes in like this:

\ -++- /
\ || /
--+\__/+--
| |
| |

With this you just press enough to overcome spring-back, and you can do
more than 90 deg if need be.

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