Bending longeron

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

wrote:
On Mar 5, 6:26 pm, "J.Kahn" wrote:

Dennis Fetters wrote:

Morgans wrote:

"J.Kahn" wrote in message
et...

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.......

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
et...

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

_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

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

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---

"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

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

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.

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