A few weeks ago I asked about bending a 2" wide x 1/4" thick x 3' length
flat stock 6061 aluminum bar into a U shape with a 7" radius. I was
concerned about the bar springing back and thus did an experiment. I
made a die using wood to form my radius.
https://www.flickr.com/photos/18223943@N06/14635585195/ and tested a
piece of 1/8" thick aluminum bar.
https://www.flickr.com/photos/182239...n/photostream/
Though, I realize the 1/8" bar is more resilient than the 1/4", the
concern of springing back presents itself as you can see
https://www.flickr.com/photos/182239...n/photostream/

Therefore, what are the possibilities of the 1/4" bar springing back and
what can I do to prevent this? Heat? It's important the bar retains it's
shape after bending.

Thank you

"Meanie" wrote in message ...

A few weeks ago I asked about bending a 2" wide x 1/4" thick x 3' length
flat stock 6061 aluminum bar into a U shape with a 7" radius. I was
concerned about the bar springing back and thus did an experiment. I
made a die using wood to form my radius.
https://www.flickr.com/photos/18223943@N06/14635585195/ and tested a
piece of 1/8" thick aluminum bar.
https://www.flickr.com/photos/182239...n/photostream/
Though, I realize the 1/8" bar is more resilient than the 1/4", the
concern of springing back presents itself as you can see
https://www.flickr.com/photos/182239...n/photostream/

Therefore, what are the possibilities of the 1/4" bar springing back and
what can I do to prevent this? Heat? It's important the bar retains it's
shape after bending.

Thank you

================================================== ================

In commercial press-brake work, springback is compensated by overbending. If
you have one of the fancy new CNC press brakes with databases of materials
and their springback properties, you can program it all in and you'll come
quite close. Otherwise, you do it the old-fashioned way: keep bending it a
little more until you get the bend you want.

That's how I do it with my sheet-metal equipment: a very big vise, some
angle iron, wooden forms, and some really big hammers. d8-)

Heat and 6061 are not a happy combination, because 6061 age-hardens and
moves, and can drive you nuts. You'll also never quite recover the
pre-heating strength, unless you put it through a carefully controlled
heat-treating cycle afterwards.

--
Ed Huntress

================================================== ================

In commercial press-brake work, springback is compensated by
overbending. If you have one of the fancy new CNC press brakes with
databases of materials and their springback properties, you can program
it all in and you'll come quite close. Otherwise, you do it the
old-fashioned way: keep bending it a little more until you get the bend
you want.

That's how I do it with my sheet-metal equipment: a very big vise, some
angle iron, wooden forms, and some really big hammers. d8-)

Heat and 6061 are not a happy combination, because 6061 age-hardens and
moves, and can drive you nuts. You'll also never quite recover the
pre-heating strength, unless you put it through a carefully controlled
heat-treating cycle afterwards.


Does that mean I should taper the ends of my wooden form for
over-bending or simply do it by hand after I remove it?

"Meanie" wrote in message ...

================================================== ================

In commercial press-brake work, springback is compensated by
overbending. If you have one of the fancy new CNC press brakes with
databases of materials and their springback properties, you can program
it all in and you'll come quite close. Otherwise, you do it the
old-fashioned way: keep bending it a little more until you get the bend
you want.

That's how I do it with my sheet-metal equipment: a very big vise, some
angle iron, wooden forms, and some really big hammers. d8-)

Heat and 6061 are not a happy combination, because 6061 age-hardens and
moves, and can drive you nuts. You'll also never quite recover the
pre-heating strength, unless you put it through a carefully controlled
heat-treating cycle afterwards.


Does that mean I should taper the ends of my wooden form for
over-bending or simply do it by hand after I remove it?

================================================== ========

I'd say that depends on how skilled you are as a handyman-metalworker. d8-)
If you can overbend by hand, that's the easier way.

--
Ed Huntress

On Sat, 12 Jul 2014 11:21:56 -0400, Meanie
wrote:

A few weeks ago I asked about bending a 2" wide x 1/4" thick x 3' length
flat stock 6061 aluminum bar into a U shape with a 7" radius. I was
concerned about the bar springing back and thus did an experiment. I
made a die using wood to form my radius.
https://www.flickr.com/photos/18223943@N06/14635585195/ and tested a
piece of 1/8" thick aluminum bar.
https://www.flickr.com/photos/182239...n/photostream/
Though, I realize the 1/8" bar is more resilient than the 1/4", the
concern of springing back presents itself as you can see
https://www.flickr.com/photos/182239...n/photostream/

Therefore, what are the possibilities of the 1/4" bar springing back and
what can I do to prevent this? Heat? It's important the bar retains it's
shape after bending.

Thank you
Calculate the springback and overbend, like any metal-worker would do

On Sat, 12 Jul 2014 12:01:17 -0400, "Ed Huntress"
wrote:



"Meanie" wrote in message ...

A few weeks ago I asked about bending a 2" wide x 1/4" thick x 3' length
flat stock 6061 aluminum bar into a U shape with a 7" radius. I was
concerned about the bar springing back and thus did an experiment. I
made a die using wood to form my radius.
https://www.flickr.com/photos/18223943@N06/14635585195/ and tested a
piece of 1/8" thick aluminum bar.
https://www.flickr.com/photos/182239...n/photostream/
Though, I realize the 1/8" bar is more resilient than the 1/4", the
concern of springing back presents itself as you can see
https://www.flickr.com/photos/182239...n/photostream/

Therefore, what are the possibilities of the 1/4" bar springing back and
what can I do to prevent this? Heat? It's important the bar retains it's
shape after bending.

Thank you

================================================= =================

In commercial press-brake work, springback is compensated by overbending. If
you have one of the fancy new CNC press brakes with databases of materials
and their springback properties, you can program it all in and you'll come
quite close. Otherwise, you do it the old-fashioned way: keep bending it a
little more until you get the bend you want.

That's how I do it with my sheet-metal equipment: a very big vise, some
angle iron, wooden forms, and some really big hammers. d8-)

Heat and 6061 are not a happy combination, because 6061 age-hardens and
moves, and can drive you nuts. You'll also never quite recover the
pre-heating strength, unless you put it through a carefully controlled
heat-treating cycle afterwards.
Not likely a big issue as IIRC the OP said 6061 was grossly
overstrength , structurally, for his application. But for the 7"
radius annealing is not required even or T6 or T651. A strong arm is
thoug. It is seriously tough stuff!!

"Meanie" wrote in message
...
================================================== ================

In commercial press-brake work, springback is compensated by
overbending. If you have one of the fancy new CNC press brakes with
databases of materials and their springback properties, you can
program
it all in and you'll come quite close. Otherwise, you do it the
old-fashioned way: keep bending it a little more until you get the
bend
you want.

That's how I do it with my sheet-metal equipment: a very big vise,
some
angle iron, wooden forms, and some really big hammers. d8-)

Heat and 6061 are not a happy combination, because 6061 age-hardens
and
moves, and can drive you nuts. You'll also never quite recover the
pre-heating strength, unless you put it through a carefully
controlled
heat-treating cycle afterwards.


Does that mean I should taper the ends of my wooden form for
over-bending or simply do it by hand after I remove it?

How accurately circular does the curve need to be? If you adjust the
legs parallel and correctly spaced by hand the curve will deform.
-jsw

How accurately circular does the curve need to be? If you adjust the
legs parallel and correctly spaced by hand the curve will deform.
-jsw



I can give way on the accuracy of the radius but it is pertinent that
the final width of the ends be 14 1/8" apart OD.

On 7/12/2014 1:08 PM, wrote:
On Sat, 12 Jul 2014 11:21:56 -0400, Meanie
wrote:

A few weeks ago I asked about bending a 2" wide x 1/4" thick x 3' length
flat stock 6061 aluminum bar into a U shape with a 7" radius. I was
concerned about the bar springing back and thus did an experiment. I
made a die using wood to form my radius.
https://www.flickr.com/photos/18223943@N06/14635585195/ and tested a
piece of 1/8" thick aluminum bar.
https://www.flickr.com/photos/182239...n/photostream/
Though, I realize the 1/8" bar is more resilient than the 1/4", the
concern of springing back presents itself as you can see
https://www.flickr.com/photos/182239...n/photostream/

Therefore, what are the possibilities of the 1/4" bar springing back and
what can I do to prevent this? Heat? It's important the bar retains it's
shape after bending.

Thank you
Calculate the springback and overbend, like any metal-worker would do

That's the problem, I'm not a metal worker nor know how to calculate for
overbend. I suppose I'll ask Google.

"Meanie" wrote in message
...


How accurately circular does the curve need to be? If you adjust
the
legs parallel and correctly spaced by hand the curve will deform.
-jsw



I can give way on the accuracy of the radius but it is pertinent
that the final width of the ends be 14 1/8" apart OD.

I would bend the sides a little beyond parallel and then open them up
with a scissors jack etc by slowly increasing the handle turns,
backing off and measuring the result. If you know that perhaps one
more turn opens the ends by 1/4" you can correct the remaining error
without as much risk of overshoot.

Or if you have a hydraulic press stop before parallel and tweak the
sides inward. Once you are close to final size you can measure and
correct for the springback.

Apply the force close to the ends of the curve or else you will bend
the flat sides.

Well, assuming you bent to size, how far back did they spring - how much too
wide are the legs now? Just bend that much further past straight, and they
should spring back basically to size. You can calculate and predict all you
want based on book properties, but in the end you bend and check and tweak
even with a cnc brake :-). Oh, it would be best to make the radius of your
form a little under, too.

-----
Regards,
Carl Ijames
"Meanie" wrote in message ...

On 7/12/2014 1:08 PM, wrote:
On Sat, 12 Jul 2014 11:21:56 -0400, Meanie
wrote:

A few weeks ago I asked about bending a 2" wide x 1/4" thick x 3' length
flat stock 6061 aluminum bar into a U shape with a 7" radius. I was
concerned about the bar springing back and thus did an experiment. I
made a die using wood to form my radius.
https://www.flickr.com/photos/18223943@N06/14635585195/ and tested a
piece of 1/8" thick aluminum bar.
https://www.flickr.com/photos/182239...n/photostream/
Though, I realize the 1/8" bar is more resilient than the 1/4", the
concern of springing back presents itself as you can see
https://www.flickr.com/photos/182239...n/photostream/

Therefore, what are the possibilities of the 1/4" bar springing back and
what can I do to prevent this? Heat? It's important the bar retains it's
shape after bending.

Thank you
Calculate the springback and overbend, like any metal-worker would do

That's the problem, I'm not a metal worker nor know how to calculate for
overbend. I suppose I'll ask Google.

"Meanie" wrote in message ...

On 7/12/2014 1:08 PM, wrote:
On Sat, 12 Jul 2014 11:21:56 -0400, Meanie
wrote:

A few weeks ago I asked about bending a 2" wide x 1/4" thick x 3' length
flat stock 6061 aluminum bar into a U shape with a 7" radius. I was
concerned about the bar springing back and thus did an experiment. I
made a die using wood to form my radius.
https://www.flickr.com/photos/18223943@N06/14635585195/ and tested a
piece of 1/8" thick aluminum bar.
https://www.flickr.com/photos/182239...n/photostream/
Though, I realize the 1/8" bar is more resilient than the 1/4", the
concern of springing back presents itself as you can see
https://www.flickr.com/photos/182239...n/photostream/

Therefore, what are the possibilities of the 1/4" bar springing back and
what can I do to prevent this? Heat? It's important the bar retains it's
shape after bending.

Thank you
Calculate the springback and overbend, like any metal-worker would do

That's the problem, I'm not a metal worker nor know how to calculate for
overbend. I suppose I'll ask Google.

================================================== ===============

I just took a look at your photos, and I have some suggestions. What you've
made is a bottoming punch and die. There is no way, IMO, that you'll get
enough force with that setup to get the bend radius you want. It would take
tons, springback or not.

If the idea is to have a fairly accurate radius and two very parallel legs,
your wooden die probably is a good place to start -- if it will hold up with
1/4 in. bar. If it will, start your bend with that.

It appears that you have a bandsaw. So I would make some round disks of
wood, starting with 1 in. less radius than your desired end result. After
making the initial bend, clamp one leg firmly and then try bending the other
leg around the smaller-radius disk -- not all the way, but just get it
started bending a bit more than your original pressing.

Check your radius before you've gone very far. If you need a smaller disk,
cut it down some more. Bend some more. If you bend the legs too far and your
radius is not right, you'll probably have to start all over again. Unbending
would likely result in little increase in the radius, but a likely "kink"
where one of the legs emerges from the bend. If the radius is too large,
with the legs parallel, it's unlikely you'll get the radius smaller by
re-bending. The bend will be harder and stronger than the legs. Or you may
get lucky. You'll need some experimenting.

The thing you'll be up against is work-hardening. If you get the legs
parallel but you need a smaller radius, unbending the legs and re-forming
the bend over a larger disk will likely cause some local work hardening that
will prevent you from ever getting it right. It could happen, as well, if
the radius needs to be larger. The tricky thing is getting the overbend just
right so the radius is right, because you will have some flexibility to bend
more or open the legs slightly to get them parallel. That's not true in
adjusting the bend radius.

Your 1/8 in. test piece would be a good start for trying this out. You know
you'll have to overbend to get the legs parallel. You'll also have to
overbend to get the radius you want. Getting that radius right is the tricky
part, so inch up on that radius while the legs are still splayed and you
have some room to adjust.

Good luck.

--
Ed Huntress

I just took a look at your photos, and I have some suggestions. What
you've made is a bottoming punch and die. There is no way, IMO, that
you'll get enough force with that setup to get the bend radius you want.
It would take tons, springback or not.

If the idea is to have a fairly accurate radius and two very parallel
legs, your wooden die probably is a good place to start -- if it will
hold up with 1/4 in. bar. If it will, start your bend with that.

It appears that you have a bandsaw. So I would make some round disks of
wood, starting with 1 in. less radius than your desired end result.
After making the initial bend, clamp one leg firmly and then try bending
the other leg around the smaller-radius disk -- not all the way, but
just get it started bending a bit more than your original pressing.

Check your radius before you've gone very far. If you need a smaller
disk, cut it down some more. Bend some more. If you bend the legs too
far and your radius is not right, you'll probably have to start all over
again. Unbending would likely result in little increase in the radius,
but a likely "kink" where one of the legs emerges from the bend. If the
radius is too large, with the legs parallel, it's unlikely you'll get
the radius smaller by re-bending. The bend will be harder and stronger
than the legs. Or you may get lucky. You'll need some experimenting.

The thing you'll be up against is work-hardening. If you get the legs
parallel but you need a smaller radius, unbending the legs and
re-forming the bend over a larger disk will likely cause some local work
hardening that will prevent you from ever getting it right. It could
happen, as well, if the radius needs to be larger. The tricky thing is
getting the overbend just right so the radius is right, because you will
have some flexibility to bend more or open the legs slightly to get them
parallel. That's not true in adjusting the bend radius.

Your 1/8 in. test piece would be a good start for trying this out. You
know you'll have to overbend to get the legs parallel. You'll also have
to overbend to get the radius you want. Getting that radius right is the
tricky part, so inch up on that radius while the legs are still splayed
and you have some room to adjust.

Good luck.


I have access to a 12,000 ton press at work which is where I was
planning to use the wooden die. Though, I believe the results of spring
back would be similar anyway even if using the press. I'll consider your
suggestions. Thank you.

"Ed Huntress" wrote in message ...



"Meanie" wrote in message ...

On 7/12/2014 1:08 PM, wrote:
On Sat, 12 Jul 2014 11:21:56 -0400, Meanie
wrote:

A few weeks ago I asked about bending a 2" wide x 1/4" thick x 3' length
flat stock 6061 aluminum bar into a U shape with a 7" radius. I was
concerned about the bar springing back and thus did an experiment. I
made a die using wood to form my radius.
https://www.flickr.com/photos/18223943@N06/14635585195/ and tested a
piece of 1/8" thick aluminum bar.
https://www.flickr.com/photos/182239...n/photostream/
Though, I realize the 1/8" bar is more resilient than the 1/4", the
concern of springing back presents itself as you can see
https://www.flickr.com/photos/182239...n/photostream/

Therefore, what are the possibilities of the 1/4" bar springing back and
what can I do to prevent this? Heat? It's important the bar retains it's
shape after bending.

Thank you
Calculate the springback and overbend, like any metal-worker would do

That's the problem, I'm not a metal worker nor know how to calculate for
overbend. I suppose I'll ask Google.

================================================== ===============

I just took a look at your photos, and I have some suggestions. What you've
made is a bottoming punch and die. There is no way, IMO, that you'll get
enough force with that setup to get the bend radius you want. It would take
tons, springback or not.

If the idea is to have a fairly accurate radius and two very parallel legs,
your wooden die probably is a good place to start -- if it will hold up with
1/4 in. bar. If it will, start your bend with that.

It appears that you have a bandsaw. So I would make some round disks of
wood, starting with 1 in. less radius than your desired end result. After
making the initial bend, clamp one leg firmly and then try bending the other
leg around the smaller-radius disk -- not all the way, but just get it
started bending a bit more than your original pressing.

Check your radius before you've gone very far. If you need a smaller disk,
cut it down some more. Bend some more. If you bend the legs too far and your
radius is not right, you'll probably have to start all over again. Unbending
would likely result in little increase in the radius, but a likely "kink"
where one of the legs emerges from the bend. If the radius is too large,
with the legs parallel, it's unlikely you'll get the radius smaller by
re-bending. The bend will be harder and stronger than the legs. Or you may
get lucky. You'll need some experimenting.

The thing you'll be up against is work-hardening. If you get the legs
parallel but you need a smaller radius, unbending the legs and re-forming
the bend over a larger disk will likely cause some local work hardening that
will prevent you from ever getting it right. It could happen, as well, if
the radius needs to be larger. The tricky thing is getting the overbend just
right so the radius is right, because you will have some flexibility to bend
more or open the legs slightly to get them parallel. That's not true in
adjusting the bend radius.

Your 1/8 in. test piece would be a good start for trying this out. You know
you'll have to overbend to get the legs parallel. You'll also have to
overbend to get the radius you want. Getting that radius right is the tricky
part, so inch up on that radius while the legs are still splayed and you
have some room to adjust.

Good luck.

--
Ed Huntress

================================================== ==================

I'm making a lot of assumptions here, such as the fact that realize that you
have to clamp something to the legs (like a 2 x 4, held on with C-clamps) so
you don't wind up bending the legs instead of your radius.

But maybe this is new to you. There's a lot of subtlety to this. Maybe it
would help if you Googled "manual tube bender" or "manual pipe bender" to
see how those elementary machines work. From that, you should be able to
figure out the dynamics of what you're trying to do.

The basic approach is to have a round forming die and a follower, with a
wheel, that forms the tube/pipe/bar around the forming die. Look at some
photos. You can make something work if you understand those principles.

The other approach is three-wheel machines, such as the ancient, elemental
Buffalo that I wrote about back in February:

http://www.nxtbook.com/nxtbooks/fabs...ruary2014/#/31

Those are the two basic approaches. The bottoming punch-and-die approach is
strictly a high-production method, because it requires job-specific tools
and big presses.

I hope I'm not adding to the confusion. It's just that it's not as simple as
it appears.

--
Ed Huntress

"Meanie" wrote in message ...


I just took a look at your photos, and I have some suggestions. What
you've made is a bottoming punch and die. There is no way, IMO, that
you'll get enough force with that setup to get the bend radius you want.
It would take tons, springback or not.

If the idea is to have a fairly accurate radius and two very parallel
legs, your wooden die probably is a good place to start -- if it will
hold up with 1/4 in. bar. If it will, start your bend with that.

It appears that you have a bandsaw. So I would make some round disks of
wood, starting with 1 in. less radius than your desired end result.
After making the initial bend, clamp one leg firmly and then try bending
the other leg around the smaller-radius disk -- not all the way, but
just get it started bending a bit more than your original pressing.

Check your radius before you've gone very far. If you need a smaller
disk, cut it down some more. Bend some more. If you bend the legs too
far and your radius is not right, you'll probably have to start all over
again. Unbending would likely result in little increase in the radius,
but a likely "kink" where one of the legs emerges from the bend. If the
radius is too large, with the legs parallel, it's unlikely you'll get
the radius smaller by re-bending. The bend will be harder and stronger
than the legs. Or you may get lucky. You'll need some experimenting.

The thing you'll be up against is work-hardening. If you get the legs
parallel but you need a smaller radius, unbending the legs and
re-forming the bend over a larger disk will likely cause some local work
hardening that will prevent you from ever getting it right. It could
happen, as well, if the radius needs to be larger. The tricky thing is
getting the overbend just right so the radius is right, because you will
have some flexibility to bend more or open the legs slightly to get them
parallel. That's not true in adjusting the bend radius.

Your 1/8 in. test piece would be a good start for trying this out. You
know you'll have to overbend to get the legs parallel. You'll also have
to overbend to get the radius you want. Getting that radius right is the
tricky part, so inch up on that radius while the legs are still splayed
and you have some room to adjust.

Good luck.


I have access to a 12,000 ton press at work which is where I was
planning to use the wooden die. Though, I believe the results of spring
back would be similar anyway even if using the press. I'll consider your
suggestions. Thank you.

================================================== =========

Oh, I thought you were trying to do this at home.

OK, then, ask a press operator. A wooden die probably won't handle bottoming
with 1/4 in. aluminum. You'll be air-bending. If your press is a press
brake, and your operator knows his stuff, he'll know how to calculate
springback with a large radius. What he may not know is whether your wooden
die will explode when you try to apply that much force to it. d8-)

I'd stand back, myself....

--
Ed Huntress

On Sat, 12 Jul 2014 12:39:48 -0400, Meanie
wrote:

================================================== ================

In commercial press-brake work, springback is compensated by
overbending. If you have one of the fancy new CNC press brakes with
databases of materials and their springback properties, you can program
it all in and you'll come quite close. Otherwise, you do it the
old-fashioned way: keep bending it a little more until you get the bend
you want.

That's how I do it with my sheet-metal equipment: a very big vise, some
angle iron, wooden forms, and some really big hammers. d8-)

Heat and 6061 are not a happy combination, because 6061 age-hardens and
moves, and can drive you nuts. You'll also never quite recover the
pre-heating strength, unless you put it through a carefully controlled
heat-treating cycle afterwards.


Does that mean I should taper the ends of my wooden form for
over-bending or simply do it by hand after I remove it?
Either one

On Sat, 12 Jul 2014 15:48:17 -0400, "Carl Ijames"
wrote:

Well, assuming you bent to size, how far back did they spring - how much too
wide are the legs now? Just bend that much further past straight, and they
should spring back basically to size. You can calculate and predict all you
want based on book properties, but in the end you bend and check and tweak
even with a cnc brake :-). Oh, it would be best to make the radius of your
form a little under, too.

-----
Regards,
Carl Ijames
"Meanie" wrote in message ...

On 7/12/2014 1:08 PM, wrote:
On Sat, 12 Jul 2014 11:21:56 -0400, Meanie
wrote:

A few weeks ago I asked about bending a 2" wide x 1/4" thick x 3' length
flat stock 6061 aluminum bar into a U shape with a 7" radius. I was
concerned about the bar springing back and thus did an experiment. I
made a die using wood to form my radius.
https://www.flickr.com/photos/18223943@N06/14635585195/ and tested a
piece of 1/8" thick aluminum bar.
https://www.flickr.com/photos/182239...n/photostream/
Though, I realize the 1/8" bar is more resilient than the 1/4", the
concern of springing back presents itself as you can see
https://www.flickr.com/photos/182239...n/photostream/

Therefore, what are the possibilities of the 1/4" bar springing back and
what can I do to prevent this? Heat? It's important the bar retains it's
shape after bending.

Thank you
Calculate the springback and overbend, like any metal-worker would do

That's the problem, I'm not a metal worker nor know how to calculate for
overbend. I suppose I'll ask Google.

Do a test bend, measure the springback. Calculate percentage. Modify
bending form by that percentage, do final bend.

On Sat, 12 Jul 2014 11:21:56 -0400, Meanie
wrote:

A few weeks ago I asked about bending a 2" wide x 1/4" thick x 3' length
flat stock 6061 aluminum bar into a U shape with a 7" radius. I was
concerned about the bar springing back and thus did an experiment. I
made a die using wood to form my radius.
https://www.flickr.com/photos/18223943@N06/14635585195/ and tested a
piece of 1/8" thick aluminum bar.
https://www.flickr.com/photos/182239...n/photostream/
Though, I realize the 1/8" bar is more resilient than the 1/4", the
concern of springing back presents itself as you can see
https://www.flickr.com/photos/182239...n/photostream/

Therefore, what are the possibilities of the 1/4" bar springing back and
what can I do to prevent this? Heat? It's important the bar retains it's
shape after bending.

Thank you

Look up the term

"annealing aluminum"

Gunner

--
"Living in the United States now is like being a Tampon.
We're in a great place, just at a bad time."