Bending longeron

[J.Kahn]

I need to make bends of about 30 degrees in a 3/4 x .049 longeron tube,
with a tight bend radius, no more than 3 inches. Can I do the bend hot
without wrinkling the tube by free bending or do I need a supporting die
of some kind? Anybody have any specific techniques?

John

[Morgans[_2_]]

"J.Kahn" > wrote in message
.. .
>I need to make bends of about 30 degrees in a 3/4 x .049 longeron tube,
>with a tight bend radius, no more than 3 inches. Can I do the bend hot
>without wrinkling the tube by free bending or do I need a supporting die of
>some kind? Anybody have any specific techniques?

Good luck, without a die bender.

I have heard of some people bending tube by packing it, very tight, with
sand. I have never done it, personally.
--
Jim in NC

[Rich S.[_1_]]

John ..........

It has been close to fifty years since I spent my days in the pipe shop at
Todd's Seattle, but memory serves well on this subject. It will be next to
impossible to make those bends without a bender having and internal stretch
die, or "bullet". Tubing with that thin of a wall and making that radius
guarantees wrinkles. Packing it with sand will help, of course.

There are low-temperature alloys with which you can fill the tube and then
bend it cold. You heat the alloy, pour it in the tube, and then melt it out
later. This is a clumsy operation and you may still wrinkle the tube. I
would take it to a pro with the right machine.

If you pack it with sand, put a wooden cork in one end of a long tube - the
longer the better. Stand it vertical, fill with fine, dry sand and then
spend an hour or so beating on the tube with a wooden hammer to pack the
sand. Start at the bottom and work your way to the top, refilling as
necessary. When you reach the top, smash in another plug, further
compressing the sand. We had a 20' hole in the floor of the shop with a
hoist overhead. There were three "rivet" hammers mounted to tap the pipe. We
would very slowly lower the pipe past the rivet hammers. After an afternoon
of constant rivet hammers, take a handful of aspirin.

If you end up with wrinkles, they may be artfully removed with a torch and
hammer, but it is difficult to do and requires much practice.

Regards,
Rich S.

"J.Kahn" > wrote in message
.. .
>I need to make bends of about 30 degrees in a 3/4 x .049 longeron tube,
>with a tight bend radius, no more than 3 inches. Can I do the bend hot
>without wrinkling the tube by free bending or do I need a supporting die of
>some kind? Anybody have any specific techniques?
>
> John

[Dennis Fetters]

Morgans wrote:
> "J.Kahn" > wrote in message
> .. .
>
>>I need to make bends of about 30 degrees in a 3/4 x .049 longeron tube,
>>with a tight bend radius, no more than 3 inches. Can I do the bend hot
>>without wrinkling the tube by free bending or do I need a supporting die of
>>some kind? Anybody have any specific techniques?
>
>

Fill the tube with water and freeze it. Bend it with the ice inside,
this will help keep it from collapsing. It's better than trying to use
sand and cheaper than low temperature metals.

[Maxwell]

"J.Kahn" > wrote in message
.. .
>I need to make bends of about 30 degrees in a 3/4 x .049 longeron tube,
>with a tight bend radius, no more than 3 inches. Can I do the bend hot
>without wrinkling the tube by free bending or do I need a supporting die of
>some kind? Anybody have any specific techniques?
>
> John

I think I would try slipping a tension spring inside the tube if you can
find one the right size. A 5/8" o.d. might be close enough, it would leave
about .025" depending on how close the tube and the spring are to actual
size.

Also, I think a 3/4" electrical conduit bender will give you about a 4"
radius, depending on brand. If that doesn't work, you might try making a
square shouldered bending shoe out of 3/4" plywood for a tube that thin.
Don't know for sure, just a wag. Thirty degrees isn't very far.

Max

[J.Kahn]

Dennis Fetters wrote:
> Morgans wrote:
>> "J.Kahn" > wrote in message
>> .. .
>>
>>> I need to make bends of about 30 degrees in a 3/4 x .049 longeron
>>> tube, with a tight bend radius, no more than 3 inches. Can I do the
>>> bend hot without wrinkling the tube by free bending or do I need a
>>> supporting die of some kind? Anybody have any specific techniques?
>>
>>
>
> Fill the tube with water and freeze it. Bend it with the ice inside,
> this will help keep it from collapsing. It's better than trying to use
> sand and cheaper than low temperature metals.


I'll experiment with that. Thanks. Doesn't the ice tend to crumble at
the bend and loose its ability to support the tube?

What about welding caps on the ends of the raw tube, one cap with a
treaded hole to take a plug, then filling with water that's had all the
air bubbles removed and plugging?

John

[Maxwell]

"Maxwell" > wrote in message
...
>
> "J.Kahn" > wrote in message
> .. .
>>I need to make bends of about 30 degrees in a 3/4 x .049 longeron tube,
>>with a tight bend radius, no more than 3 inches. Can I do the bend hot
>>without wrinkling the tube by free bending or do I need a supporting die
>>of some kind? Anybody have any specific techniques?
>>
>> John
>
> I think I would try slipping a tension spring inside the tube if you can
> find one the right size. A 5/8" o.d. might be close enough, it would
> leave about .025" depending on how close the tube and the spring are to
> actual size.
>
> Also, I think a 3/4" electrical conduit bender will give you about a 4"
> radius, depending on brand. If that doesn't work, you might try making a
> square shouldered bending shoe out of 3/4" plywood for a tube that thin.
> Don't know for sure, just a wag. Thirty degrees isn't very far.
>
> Max

Come to think of it, you might be able to wrap another spring around the
outside, and go 30 degrees without a benging shoe. But obviously I'm still
guessing.

*Nothing is too difficult for the man that doesn't have to actually do it.*

[Don W]

J.Kahn wrote:
> I need to make bends of about 30 degrees in a 3/4 x .049 longeron tube,
> with a tight bend radius, no more than 3 inches. Can I do the bend hot
> without wrinkling the tube by free bending or do I need a supporting die
> of some kind? Anybody have any specific techniques?
>
> John

John,

They make special heavy springs which fit inside
tubes to support the inside radius of the bend and
keep it from collapsing when you bend it. Pulling
on the spring causes its outside diameter to get
slightly smaller so that you can get it out of the
bent tube after you're done.

Check at automotive parts stores and Harbor Freight.

Good luck with it,

Don W.

[jerry wass]

J.Kahn wrote:
> I need to make bends of about 30 degrees in a 3/4 x .049 longeron tube,
> with a tight bend radius, no more than 3 inches. Can I do the bend hot
> without wrinkling the tube by free bending or do I need a supporting die
> of some kind? Anybody have any specific techniques?
>
> John
--I bent some of the same tube by filling it with sand, bending it
around a 10" pulley that had been turned out inside to 3/8"
radius--Pulling it around with the inner race of a big ball brg that had
used 3/4" balls--this was pressed onto a smaller brg which was bolted to
a bar that pivoted on the center support of the pulley. BUT--
that's a 5" radius & you want 3"---might do it though..send ya a pic if
your interested. wass biplane at tds dot net

[Lou]

On Mar 5, 2:29 pm, Jerry Wass > wrote:
> J.Kahn wrote:
> > I need to make bends of about 30 degrees in a 3/4 x .049 longeron tube,
> > with a tight bend radius, no more than 3 inches. Can I do the bend hot
> > without wrinkling the tube by free bending or do I need a supporting die
> > of some kind? Anybody have any specific techniques?
>
> > John
>
> --I bent some of the same tube by filling it with sand, bending it
> around a 10" pulley that had been turned out inside to 3/8"
> radius--Pulling it around with the inner race of a big ball brg that had
> used 3/4" balls--this was pressed onto a smaller brg which was bolted to
> a bar that pivoted on the center support of the pulley. BUT--
> that's a 5" radius & you want 3"---might do it though..send ya a pic if
> your interested. wass biplane at tds dot net

Can't you use a conduit bender?
Lou

[J.Kahn]

Lou wrote:
> On Mar 5, 2:29 pm, Jerry Wass > wrote:
>> J.Kahn wrote:
>>> I need to make bends of about 30 degrees in a 3/4 x .049 longeron tube,
>>> with a tight bend radius, no more than 3 inches. Can I do the bend hot
>>> without wrinkling the tube by free bending or do I need a supporting die
>>> of some kind? Anybody have any specific techniques?
>>> John
>> --I bent some of the same tube by filling it with sand, bending it
>> around a 10" pulley that had been turned out inside to 3/8"
>> radius--Pulling it around with the inner race of a big ball brg that had
>> used 3/4" balls--this was pressed onto a smaller brg which was bolted to
>> a bar that pivoted on the center support of the pulley. BUT--
>> that's a 5" radius & you want 3"---might do it though..send ya a pic if
>> your interested. wass biplane at tds dot net
>
> Can't you use a conduit bender?
> Lou
>
Apparently you can but the radius I need is smaller than a conduit bender.

[Morgans[_2_]]

"J.Kahn" > wrote

> Apparently you can but the radius I need is smaller than a conduit bender.

Use that, then tweak it?
--
Jim in NC

[Dennis Fetters]

J.Kahn wrote:

> Dennis Fetters wrote:
>
>> Morgans wrote:
>>
>>> "J.Kahn" > wrote in message
>>> .. .
>>>
>>>> I need to make bends of about 30 degrees in a 3/4 x .049 longeron
>>>> tube, with a tight bend radius, no more than 3 inches. Can I do
>>>> the bend hot without wrinkling the tube by free bending or do I need
>>>> a supporting die of some kind? Anybody have any specific techniques?
>>>
>>>
>>>
>>
>> Fill the tube with water and freeze it. Bend it with the ice inside,
>> this will help keep it from collapsing. It's better than trying to use
>> sand and cheaper than low temperature metals.
>
>
>
> I'll experiment with that. Thanks. Doesn't the ice tend to crumble at
> the bend and loose its ability to support the tube?
>
> What about welding caps on the ends of the raw tube, one cap with a
> treaded hole to take a plug, then filling with water that's had all the
> air bubbles removed and plugging?
>
> John

Yes it crumbles, but the ice expands inside the tube giving gripping
power, so the uncrumbled ice on either side of the bend holds the
crushed ice in place. Good luck

[Ernest Christley]

Morgans wrote:
> "J.Kahn" > wrote in message
> .. .
>> I need to make bends of about 30 degrees in a 3/4 x .049 longeron tube,
>> with a tight bend radius, no more than 3 inches. Can I do the bend hot
>> without wrinkling the tube by free bending or do I need a supporting die of
>> some kind? Anybody have any specific techniques?
>
> Good luck, without a die bender.
>
> I have heard of some people bending tube by packing it, very tight, with
> sand. I have never done it, personally.

We're only talking 30 degrees here guys. Sheesh!

Mark on either side of your 30 degrees. Heat the inside of the bend in
the area between the marks to a dull red, then each of you grab a side
and bend it into the hot area as if you were back peddling a canoe.
Don't add a lot of pressure. You're just "assisting" the torch heat.
Let it cool completely, and do it again if you don't have enough bend.

[GeorgeB]

A standard hydraulic tubing bender for 3/4 OD tubing has a 3" radius
to tube centerline and says the minimum wall without flattening is
0.049 for "high strength" aluminum, or any for soft aluminum. If you
have a piece to try, head to your local hydraulic shop and ask them to
try.

With inner support, there is lots more capability, and as close as
this is, the spring will probably be enough.

On Mon, 05 Mar 2007 11:01:37 -0500, "J.Kahn"
> wrote:

>I need to make bends of about 30 degrees in a 3/4 x .049 longeron tube,
>with a tight bend radius, no more than 3 inches. Can I do the bend hot
>without wrinkling the tube by free bending or do I need a supporting die
>of some kind? Anybody have any specific techniques?
>
>John

[[email protected]]

On Mar 5, 9:01 am, "J.Kahn" > wrote:
> I need to make bends of about 30 degrees in a 3/4 x .049 longeron tube,
> with a tight bend radius, no more than 3 inches. Can I do the bend hot
> without wrinkling the tube by free bending or do I need a supporting die
> of some kind? Anybody have any specific techniques?
>
> John

This is easy to do with a torch. Secure the tube to your table, with
the horizontal tube tacked into place forward of the bend. Set your
torch with a neutral flame and heat to cherry red for about 2.5 inches
either side of the bend. Slowly bend to the desired dimension. If
your using a wood topped jig table, place a small piece of steel
between the tube and the table. Header wrap also works well to keep
from burning the table too much. If you're bending both the top and
bottom longeron you will have to alternately heat each tube at the
same time. If you're bending one tube alone, a conduit bender works
well. Practice with cheap conduit to get the hang of it first. Also
practice your bending with the torch on small scrap 4130 until you
feel confident with the process. If you go slowly, and don't over
heat, you will have a nice radius bend with no wrinkle.

Colin

http://www.jumprunenterprises.com

[[email protected]]

On Mar 5, 6:26 pm, "J.Kahn" > wrote:
> Dennis Fetters wrote:
> > Morgans wrote:
> >> "J.Kahn" > wrote in message
> .. .
>
> >>> I need to make bends of about 30 degrees in a 3/4 x .049 longeron
> >>> tube, with a tight bend radius, no more than 3 inches. Can I do the
> >>> bend hot without wrinkling the tube by free bending or do I need a
> >>> supporting die of some kind? Anybody have any specific techniques?
>
> > Fill the tube with water and freeze it. Bend it with the ice inside,
> > this will help keep it from collapsing. It's better than trying to use
> > sand and cheaper than low temperature metals.
>
> I'll experiment with that. Thanks. Doesn't the ice tend to crumble at
> the bend and loose its ability to support the tube?

I'm sure it would crumble but the crumbled ice still won't compress.

>
> What about welding caps on the ends of the raw tube, one cap with a
> treaded hole to take a plug, then filling with water that's had all the
> air bubbles removed and plugging?
>

That is similar to filling it with ice except the ice is it's own
plug
and in the process of freezing it will expand, expanding the tube
to a larger diameter, or maybe splitting it, whereas filling with
water may result in the volume lost by kinking the pipe at the bend
being made up for by expanding the diameter somewhere else.

Are you sure that a weldment isn't a better design approach?
I.e. cut wedges from the inside radius, bend it, weld it. If it
MUST be smooth grind the welds flush.

--

FF

[Dennis Fetters]

wrote:
> On Mar 5, 6:26 pm, "J.Kahn" > wrote:
>
>>Dennis Fetters wrote:
>>
>>>Morgans wrote:
>>>
>>>>"J.Kahn" > wrote in message
.. .
>>
>>>>>I need to make bends of about 30 degrees in a 3/4 x .049 longeron
>>>>>tube, with a tight bend radius, no more than 3 inches. Can I do the
>>>>>bend hot without wrinkling the tube by free bending or do I need a
>>>>>supporting die of some kind? Anybody have any specific techniques?
>>
>>>Fill the tube with water and freeze it. Bend it with the ice inside,
>>>this will help keep it from collapsing. It's better than trying to use
>>>sand and cheaper than low temperature metals.
>>
>>I'll experiment with that. Thanks. Doesn't the ice tend to crumble at
>>the bend and loose its ability to support the tube?
>
>
> I'm sure it would crumble but the crumbled ice still won't compress.
>
>
>> What about welding caps on the ends of the raw tube, one cap with a
>>treaded hole to take a plug, then filling with water that's had all the
>>air bubbles removed and plugging?
>>
>
>
> That is similar to filling it with ice except the ice is it's own
> plug
> and in the process of freezing it will expand, expanding the tube
> to a larger diameter, or maybe splitting it, whereas filling with
> water may result in the volume lost by kinking the pipe at the bend
> being made up for by expanding the diameter somewhere else.
>
> Are you sure that a weldment isn't a better design approach?
> I.e. cut wedges from the inside radius, bend it, weld it. If it
> MUST be smooth grind the welds flush.
>
> --
>
> FF

Well, shoot. I guess I need to stop using ice as a method of bending
tubing if it won't work. I wish I would have know that 30 years ago, I
would have not waited all my time bending tubes that way to keep them
from distorting.......

[[email protected]]

On Mar 13, 9:02 pm, Dennis Fetters >
wrote:
> wrote:
> > On Mar 5, 6:26 pm, "J.Kahn" > wrote:
>
> >>Dennis Fetters wrote:
>
> >>>Morgans wrote:
>
> >>>>"J.Kahn" > wrote in message
> .. .
>
> >>>>>I need to make bends of about 30 degrees in a 3/4 x .049 longeron
> >>>>>tube, with a tight bend radius, no more than 3 inches. Can I do the
> >>>>>bend hot without wrinkling the tube by free bending or do I need a
> >>>>>supporting die of some kind? Anybody have any specific techniques?
>
> >>>Fill the tube with water and freeze it. Bend it with the ice inside,
> >>>this will help keep it from collapsing. It's better than trying to use
> >>>sand and cheaper than low temperature metals.
>
> >>I'll experiment with that. Thanks. Doesn't the ice tend to crumble at
> >>the bend and loose its ability to support the tube?
>
> > I'm sure it would crumble but the crumbled ice still won't compress.
>
> >> What about welding caps on the ends of the raw tube, one cap with a
> >>treaded hole to take a plug, then filling with water that's had all the
> >>air bubbles removed and plugging?
>
> > That is similar to filling it with ice except the ice is it's own
> > plug
> > and in the process of freezing it will expand, expanding the tube
> > to a larger diameter, or maybe splitting it, whereas filling with
> > water may result in the volume lost by kinking the pipe at the bend
> > being made up for by expanding the diameter somewhere else.
>
> > Are you sure that a weldment isn't a better design approach?
> > I.e. cut wedges from the inside radius, bend it, weld it. If it
> > MUST be smooth grind the welds flush.
>
> > --
>
> > FF
>
> Well, shoot. I guess I need to stop using ice as a method of bending
> tubing if it won't work. I wish I would have know that 30 years ago, I
> would have not waited all my time bending tubes that way to keep them
> from distorting.......

I didn't say it won't work, just pointed out that there might be some
problems with it for any specific application. Freezing water in
steel water pipes can burst them as many homeowners have
discovered.

--

FF

[Morgans[_2_]]

> _said_

>> >>Dennis Fetters wrote:
>>
>> >>>Morgans wrote:
>>
>> >>>>"J.Kahn"> wrote: "A Whole Bunch of Stuff" from old posts.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Fred, you need to do some serious work on your trimming and snipping skills.

Most of those old, old posts and "so-and-so wrote's" could have, and should
have been trimmed "right out" of your reply.

As you are probably unaware, my name was in there as having "wrote"
something on your most recent post, but not one word on your post came from
any of my posts. I don't like (mostly on principle) being quoted when there
is nothing there I said.

I think you will understand, and will try harder, next time. :-)
--
Jim in NC

[[email protected]]

On Mar 13, 10:28 pm, "Morgans" > wrote:
> > _said_
>
> ...
>
> As you are probably unaware, my name was in there as having "wrote"
> something on your most recent post,

Sort of.

> but not one word on your post came from
> any of my posts. I don't like (mostly on principle)
> being quoted when there
> is nothing there I said.

A reader can figure that out by counting the ">>>..."

>
> I think you will understand, and will try harder, next time. :-)

Yes, you're right, I should be more careful.

--

FF

[jerry wass]

wrote:
> On Mar 13, 10:28 pm, "Morgans" > wrote:
>> > _said_
>>
>> ...
>>
>> As you are probably unaware, my name was in there as having "wrote"
>> something on your most recent post,
>
> Sort of.
>
>> but not one word on your post came from
>> any of my posts. I don't like (mostly on principle)
>> being quoted when there
>> is nothing there I said.
>
> A reader can figure that out by counting the ">>>..."
>
>> I think you will understand, and will try harder, next time. :-)
>
> Yes, you're right, I should be more careful.
>
> --
>
> FF
>
>
> Well my method WORKS, AND WORKS GOOD, & I can show you pics of my Stabilizer to prove it.
Jerry---posted 3 or 4 days ago---

[Morgans[_2_]]

"Jerry Wass" > wrote

> Well my method WORKS, AND WORKS GOOD, & I can show you pics of my
> Stabilizer to prove it.
> Jerry---posted 3 or 4 days ago---
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Jerry, I have my views set to get rid of posts that far back.

What was your method, again? I quick reminder will suffice! <g>
--
Jim in NC

[Morgans[_2_]]

"Richard Riley" > wrote

> Jerry's method was -
> ---------------------------------------------
> --I bent some of the same tube by filling it with sand, bending it
> around a 10" pulley that had been turned out inside to 3/8"
> radius--Pulling it around with the inner race of a big ball brg that
> had
> used 3/4" balls--this was pressed onto a smaller brg which was bolted
> to
> a bar that pivoted on the center support of the pulley. BUT--
> that's a 5" radius & you want 3"---might do it though..send ya a pic
> if
> your interested. wass biplane at tds dot net

So, it was almost a homebrewed commercial bender, it sounds like.
--
Jim in NC

[jerry wass]

Morgans wrote:
> "Jerry Wass" > wrote
>
>> Well my method WORKS, AND WORKS GOOD, & I can show you pics of my
>> Stabilizer to prove it.
>> Jerry---posted 3 or 4 days ago---
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> Jerry, I have my views set to get rid of posts that far back.
>
> What was your method, again? I quick reminder will suffice! <g>


it's still there 3-5---2:29 pm---Jerry---I sent someone some pics also...

[jerry wass]

Morgans wrote:
> "Richard Riley" > wrote
>
>> Jerry's method was -
>> ---------------------------------------------
>> --I bent some of the same tube by filling it with sand, bending it
>> around a 10" pulley that had been turned out inside to 3/8"
>> radius--Pulling it around with the inner race of a big ball brg that
>> had
>> used 3/4" balls--this was pressed onto a smaller brg which was bolted
>> to
>> a bar that pivoted on the center support of the pulley. BUT--
>> that's a 5" radius & you want 3"---might do it though..send ya a pic
>> if
>> your interested. wass biplane at tds dot net
>
> So, it was almost a homebrewed commercial bender, it sounds like.

Yeah, I just happened to have the parts & a lathe--so it wasn't too much
effort---BTW the radius was more like 4" rather than the 5" I first
recalled--(two-groove pulley, used smaller one.)

[J.Kahn]

Dennis Fetters wrote:

>
> Well, shoot. I guess I need to stop using ice as a method of bending
> tubing if it won't work. I wish I would have know that 30 years ago, I
> would have not waited all my time bending tubes that way to keep them
> from distorting.......

Dennis can the bending die that is used to set the radius be flat, like
a block of wood with inside radius cut into it?


John

[Dennis Fetters]

J.Kahn wrote:
> Dennis Fetters wrote:
>
>>
>> Well, shoot. I guess I need to stop using ice as a method of bending
>> tubing if it won't work. I wish I would have know that 30 years ago, I
>> would have not waited all my time bending tubes that way to keep them
>> from distorting.......
>
>
> Dennis can the bending die that is used to set the radius be flat, like
> a block of wood with inside radius cut into it?
>
>
> John

Hi John,

Both the inner and outer die must have the same radius as the tube being
bent. On the outer die, I use a flat bar with the radius cut into it.
(four sides to the bar, four different radius) Then on the back side of
the bar is a roller, that draws the bar around the inner radius, leaving
no scratches on the tube. Hope this helps.

[jerry wass]

Dennis Fetters wrote:
> J.Kahn wrote:
>> Dennis Fetters wrote:
>>
>>>
>>> Well, shoot. I guess I need to stop using ice as a method of bending
>>> tubing if it won't work. I wish I would have know that 30 years ago,
>>> I would have not waited all my time bending tubes that way to keep
>>> them from distorting.......
>>
>>
>> Dennis can the bending die that is used to set the radius be flat,
>> like a block of wood with inside radius cut into it?
>>
>>
>> John
>
> Hi John,
>
> Both the inner and outer die must have the same radius as the tube being
> bent. On the outer die, I use a flat bar with the radius cut into it.
> (four sides to the bar, four different radius) Then on the back side of
> the bar is a roller, that draws the bar around the inner radius, leaving
> no scratches on the tube. Hope this helps.

Great Idea, A simple way to obviate having a set of outer rollers ,one
for each size---The bar is only long enough to make the longest curve
you desire, and "floats" between the tube and the roller--i.e. not
attached anywhere on the machine--The roller is mounted on a bar that is
pivoted at the center of the inner rasius die.--then you only have to
have an inner die with the correct radius of the curve & for the tubing.

Jerry