I use my HF 20T H press as a press brake with a homemade die. I'm
trying to put a fairly sharp 90 deg bend in a 20" piece of 16 ga mild
steel and I'm getting too much deflection in the ends of the die. The
bend isn't completed because of this. There's about 3" of stock that
doesn't have enough bend.

Here is the die, front view & cross section:
http://home.comcast.net/~bobengelhardt/PressDie.jpg
http://home.comcast.net/~bobengelhardt/PressDieEnd.jpg

I'm thinking to strengthen it with a couple of wings, as shown in red on
the right side. Maybe 1/4" plate, 3 or 4" wide/high.

Do you think that this will be enough? Would a flange on top of the
wing add significantly?

Thanks,
Bob

On Dec 15, 8:06*pm, Bob Engelhardt wrote:
I use my HF 20T H press as a press brake with a homemade die. *I'm
trying to put a fairly sharp 90 deg bend in a 20" piece of 16 ga mild
steel and I'm getting too much deflection in the ends of the die. *The
bend isn't completed because of this. *There's about 3" of stock that
doesn't have enough bend.

Here is the die, front view & cross section:http://home.comcast.net/~bobengelhar...ressDieEnd.jpg

I'm thinking to strengthen it with a couple of wings, as shown in red on
the right side. *Maybe 1/4" plate, 3 or 4" wide/high.

Do you think that this will be enough? *Would a flange on top of the
wing add significantly?

Thanks,
Bob

Couldn't you just put in some spacers so the ends are supported by the
HF press.

Dan

On Tue, 15 Dec 2009 15:06:17 -0500, Bob Engelhardt
wrote:

I use my HF 20T H press as a press brake with a homemade die. I'm
trying to put a fairly sharp 90 deg bend in a 20" piece of 16 ga mild
steel and I'm getting too much deflection in the ends of the die. The
bend isn't completed because of this. There's about 3" of stock that
doesn't have enough bend.

Here is the die, front view & cross section:
http://home.comcast.net/~bobengelhardt/PressDie.jpg
http://home.comcast.net/~bobengelhardt/PressDieEnd.jpg

I'm thinking to strengthen it with a couple of wings, as shown in red on
the right side. Maybe 1/4" plate, 3 or 4" wide/high.

Do you think that this will be enough?

I dunno without doing the math.

Would a flange on top of the
wing add significantly?

A flange would make a very big difference. You can get a feel for how
much by playing with the T and I shapes on the "common" tab he

http://www.engineeringcalculator.net...roperties.html

Stiffness in the vertical direction is proportional to Ix.

--
Ned Simmons

On Dec 15, 3:06*pm, Bob Engelhardt wrote:
...There's about 3" of stock that
doesn't have enough bend.

Here is the die, front view & cross section:http://home.comcast.net/~bobengelhar...ressDieEnd.jpg

Bob

Rearrange the dies so you can swivel them at an angle to the frame
and press the end of the work in the center of the die.

jsw

On Tue, 15 Dec 2009 15:06:17 -0500, Bob Engelhardt
wrote:


Do you think that this will be enough? Would a flange on top of the
wing add significantly?

Thanks,
Bob


Take out the central support and replace it with two similar supports about
10% from each end.

If you still get excessive deflection, then weld in a plate along the beam and
between the supports. In the first case, you've greatly minimised the
cantilevered length that's under load. In the second, the top edge of the
(relatively thin) plate will be under tension and will be less likely to
buckle than in your picture.

Mark Rand
RTFM

On Dec 15, 10:43*pm, Mark Rand wrote:


Take out the central support and replace it with two similar supports about
10% from each end.

Mark Rand
RTFM

Why not leave the central support and add two similar supports close
to the ends? Wouldn't that be less work and more rigid? Somehow I
have the feeling that I do not see the whole picture.

Dan

wrote:
Couldn't you just put in some spacers so the ends are supported by the
HF press.

Dang! You know, that was my 1st idea & I rejected 'cause I was thinking
that only the center pin moved. But of course the whole bar moves &
that is just the right solution!

I just finished doing it. I used some 3/4" all thread that I got at the
dump. Having the spacers adjustable turned out to be a really good idea
- it needed a bit of tweaking.

http://home.comcast.net/~bobengelhardt/PressDieFix.jpg

I works much better - almost good enough. The problem now is that the
female part wasn't made accurately enough. Its sides are not quite
parallel.

Thanks,
Bob

Ned Simmons wrote:
A flange would make a very big difference. You can get a feel for how
much by playing with the T and I shapes on the "common" tab he

http://www.engineeringcalculator.net...roperties.html
....

Thanks for the reference - it's been filed. Bob

Jim Wilkins wrote:
Rearrange the dies so you can swivel them at an angle to the frame
and press the end of the work in the center of the die.

That's a cool idea - you could bend any length that way, in steps. It's
on my list.

Thanks,
Bob

Mark Rand wrote:
Take out the central support and replace it with two similar supports about
10% from each end.

If you still get excessive deflection, then weld in a plate along the beam and
between the supports. ...

Ah, that sounds even better than what I did ... too late.

Thanks,
Bob

Bob Engelhardt wrote:
Jim Wilkins wrote:
Rearrange the dies so you can swivel them at an angle to the frame
and press the end of the work in the center of the die.

That's a cool idea - you could bend any length that way, in steps. It's
on my list.

Oops - that won't work when either leg of the finished bend is over 10"
or so. At that length the leg will hit the beam that the jack sits on.
Probably most of my bends have a leg longer than that, so it's no-go
for me. Thanks anyway - keep up the thinking G.

Bob

spaco wrote:
... when I made my
press brakes, I simply used large square stock mounted "on the diamond"
for upper dies ...
The largest one I made uses 1 1/2" square stock.

Definitely better. I used what I had on hand, which I do whenever I can.

I like the solution you got about adding jack screws to the ends. As
long as you aren't bending anything thicker than 16 ga that wide, you
will probably be okay, but it you were really pushing the press, I might
worry that the channel the jack sits on might bend from the end forces.
...

I realized that & figured I was OK, for the 16 ga. Given that the die
itself *almost* handled the load, the force on the jack beam would not
be that much. Any bend on thicker material would be much narrower stock.

... 2 pieces of
3/8" stock tack welded to a piece of 1/2" plate. The spacing between
the 3/8" plates is about 1/2". ... since the
"groove" is shallow, it's easier to get good alignment than with a
bigger female "vee", or with the round rod approach.

Yeah - that alignment is a challenge. If the male die was sharp it
would be easier, but that's not a good idea. How about a laser aligner
- mount at the side, shining across the gap in the female die. Might
work pretty well. Damn, I just threw away the guts from something that
had a laser.

Also, because the groove is narrower, the bend starts closer to the
actual corner you are trying to produce when you want a sharp bend.
When the "groove" is wider, bending starts over a wider area, so, I
think you actually end up back bending the stock in the fixture to
correct for that as you approach 90°.

Good point - why do you need a groove wider than the finished bend?

Keep on making stuff for your press,

I'm trying - I'm bending as fast as I can G.

Bob

That's a great idea!

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

Bob Engelhardt wrote:



Yeah - that alignment is a challenge. If the male die was sharp it
would be easier, but that's not a good idea. How about a laser aligner
- mount at the side, shining across the gap in the female die. Might
work pretty well. Damn, I just threw away the guts from something that
had a laser.