Hi,

I am new to the concept of steam bending and am experimenting with
very little success.

In easy terms to understand how flexible would a piece of oak that is
1" thick x 3" wide become?

How tight of radius can be formed before breaking the piece?

I experimented with laying a short piece on top of a boiling pot of
water with a lid above the oak for 1.5 hours and could not tell any
difference between before and after. It was still very rigid.

How flexible should the wood be if using a steam box? I understand
how to build the steam box.

I just don't have a bench mark to estimate how much or little force is
needed to bend. I have heard people say that it turns the wood into a
noodle for a short amount of time. Based on my limited
experiment...I find this hard to believe.

One more question is how much of the integrity is lost after
application of the steam? I have heard that the steam destroys the
cell structure of the wood.

My alternate is to saw the wood from thicker to make the frames
needed.

thanks,
marshall

MarshallE wrote:


I am new to the concept of steam bending and am experimenting with
very little success.
snip

Before getting into the nitty gritty, what are you trying to do.

Lew

"MarshallE" wrote in message
ups.com...
Hi,

I am new to the concept of steam bending and am experimenting with
very little success.

In easy terms to understand how flexible would a piece of oak that is
1" thick x 3" wide become?

How tight of radius can be formed before breaking the piece?

I experimented with laying a short piece on top of a boiling pot of
water with a lid above the oak for 1.5 hours and could not tell any
difference between before and after. It was still very rigid.

How flexible should the wood be if using a steam box? I understand
how to build the steam box.

I just don't have a bench mark to estimate how much or little force is
needed to bend. I have heard people say that it turns the wood into a
noodle for a short amount of time. Based on my limited
experiment...I find this hard to believe.

One more question is how much of the integrity is lost after
application of the steam? I have heard that the steam destroys the
cell structure of the wood.

My alternate is to saw the wood from thicker to make the frames
needed.

thanks,
marshall


Try posting on the rec woodworking NG there has been a lot of posts on
steaming wood over the years there. If you can find the archives for that
group you should be able to find you answers and more.
Jim

MarshallE wrote:
Hi,

I am new to the concept of steam bending and am experimenting with
very little success.

In easy terms to understand how flexible would a piece of oak that is
1" thick x 3" wide become?

How tight of radius can be formed before breaking the piece?

I experimented with laying a short piece on top of a boiling pot of
water with a lid above the oak for 1.5 hours and could not tell any
difference between before and after. It was still very rigid.

How flexible should the wood be if using a steam box? I understand
how to build the steam box.

I just don't have a bench mark to estimate how much or little force is
needed to bend. I have heard people say that it turns the wood into a
noodle for a short amount of time. Based on my limited
experiment...I find this hard to believe.

One more question is how much of the integrity is lost after
application of the steam? I have heard that the steam destroys the
cell structure of the wood.

My alternate is to saw the wood from thicker to make the frames
needed.

First off, the way you're doing it is not going to cut it. Make a real
steam box.

Secondly, the type of wood (green, air-dried, kiln-dried) makes a
substantial difference. Kiln-dried wood is much more difficult to bend.

Third, define "short". If you're talking about a 12" piece of 1x3 oak,
you're never going to notice any difference in stiffness as you don't
have enough leverage to bend it. Stock that size is not going to get
limp, no matter what you do with it and it will require considerable
force to bend it. Start with stock that's at least 24" long and you'll
see the difference.

On Jun 22, 8:32 am, Brian Nystrom wrote:
MarshallE wrote:
Hi,

I am new to the concept of steam bending and am experimenting with
very little success.

In easy terms to understand how flexible would a piece of oak that is
1" thick x 3" wide become?

How tight of radius can be formed before breaking the piece?

I experimented with laying a short piece on top of a boiling pot of
water with a lid above the oak for 1.5 hours and could not tell any
difference between before and after. It was still very rigid.

How flexible should the wood be if using a steam box? I understand
how to build the steam box.

I just don't have a bench mark to estimate how much or little force is
needed to bend. I have heard people say that it turns the wood into a
noodle for a short amount of time. Based on my limited
experiment...I find this hard to believe.

One more question is how much of the integrity is lost after
application of the steam? I have heard that the steam destroys the
cell structure of the wood.

My alternate is to saw the wood from thicker to make the frames
needed.

First off, the way you're doing it is not going to cut it. Make a real
steam box.

Secondly, the type of wood (green, air-dried, kiln-dried) makes a
substantial difference. Kiln-dried wood is much more difficult to bend.

Third, define "short". If you're talking about a 12" piece of 1x3 oak,
you're never going to notice any difference in stiffness as you don't
have enough leverage to bend it. Stock that size is not going to get
limp, no matter what you do with it and it will require considerable
force to bend it. Start with stock that's at least 24" long and you'll
see the difference.- Hide quoted text -

- Show quoted text -

Yeah, make a real steam box and figure 15 minutes for each 1/4 inch.
You will need to leave the board long so you have enough leverage to
do this. If you don't steam long enough, it will snap, if you steam
too long it can get mushy and basically tear. I use a big box and a
turkey frier to steam wood. I made a top for the pan and put a
radiator hose from it to the box.

wrote:
On Jun 22, 8:32 am, Brian Nystrom wrote:
MarshallE wrote:
Hi,
I am new to the concept of steam bending and am experimenting with
very little success.
In easy terms to understand how flexible would a piece of oak that is
1" thick x 3" wide become?
How tight of radius can be formed before breaking the piece?
I experimented with laying a short piece on top of a boiling pot of
water with a lid above the oak for 1.5 hours and could not tell any
difference between before and after. It was still very rigid.
How flexible should the wood be if using a steam box? I understand
how to build the steam box.
I just don't have a bench mark to estimate how much or little force is
needed to bend. I have heard people say that it turns the wood into a
noodle for a short amount of time. Based on my limited
experiment...I find this hard to believe.
One more question is how much of the integrity is lost after
application of the steam? I have heard that the steam destroys the
cell structure of the wood.
My alternate is to saw the wood from thicker to make the frames
needed.
First off, the way you're doing it is not going to cut it. Make a real
steam box.

Secondly, the type of wood (green, air-dried, kiln-dried) makes a
substantial difference. Kiln-dried wood is much more difficult to bend.

Third, define "short". If you're talking about a 12" piece of 1x3 oak,
you're never going to notice any difference in stiffness as you don't
have enough leverage to bend it. Stock that size is not going to get
limp, no matter what you do with it and it will require considerable
force to bend it. Start with stock that's at least 24" long and you'll
see the difference.- Hide quoted text -

- Show quoted text -

Yeah, make a real steam box and figure 15 minutes for each 1/4 inch.
You will need to leave the board long so you have enough leverage to
do this. If you don't steam long enough, it will snap, if you steam
too long it can get mushy and basically tear. I use a big box and a
turkey frier to steam wood. I made a top for the pan and put a
radiator hose from it to the box.

A good alternative steam source is a Wagner Wallpaper Steamer. They're
~$50 and produce enough steam to run a decent sized box, at least big
enough for the stock the poster is asking about.

A piece of 1" red oak can be bent to radius of 1" if supported by a
metal strap and 11.5" unsupported according to "wood Bending Handbook"
published by Woodcraft Supply. That sounds about right to me as long
as the strap is fixed at both ends so that the neutral axis is pushed
to the outer radius. Also, remember that it is primarily the heat that
plasticizes wood and that you do not gain any additional softening by
heating the wood beyond the boiling point of water. Luthiers use dry
heat as did barrel makers. I have never had very good results from
simply getting the work piece wet, it must get hot.

If you need to do further testing for your application before building
a steam box you can try boiling the piece of wood or wrapping the
section that you need to bend in rags and pour lots and lots of
boiling water over the rags.

Leverage helps but does not prevent breaking or crushing the grain on
the inner radius. Bending over matched male and female forms with
plenty of clamps does help.

On Jun 25, 10:36 am, Todd wrote:
A piece of 1" red oak can be bent to radius of 1" if supported by a
metal strap and 11.5" unsupported according to "wood Bending Handbook"
published by Woodcraft Supply.

I think you meant that one inch oak can be bent to a radius of one
foot! I am sure most caught that though.

That sounds about right to me as long
as the strap is fixed at both ends so that the neutral axis is pushed
to the outer radius. Also, remember that it is primarily the heat that
plasticizes wood and that you do not gain any additional softening by
heating the wood beyond the boiling point of water.

Exactly, if you heat it to much it either crushes, or tears. Like I
said, a general rule is 15 min/quarter inch of thickness.

Luthiers use dry
heat as did barrel makers. I have never had very good results from
simply getting the work piece wet, it must get hot.

If you need to do further testing for your application before building
a steam box you can try boiling the piece of wood or wrapping the
section that you need to bend in rags and pour lots and lots of
boiling water over the rags.

I don't think you could get enough consistancy with rags on 1 inch
thick oak. I think the benefit of wet wood is transfering heat more
evenly thorough the piece.


Leverage helps but does not prevent breaking or crushing the grain on
the inner radius. Bending over matched male and female forms with
plenty of clamps does help.

A note. Once wood has been steamed once, the cells will not soften
again with heat. Also, when you remove the part from the steam, you
have literally seconds, maybe 7-10 to get the part bent or it will
cool and lose it's ability to bend, it will most likely crack. Always
make your radius a little smaller, it is much easier to open up a
radius part later that way, than to try to bend it more closed on
installation. You must also leave an extra foot or more on each end of
1 inch oak so you have some leverage, even after steaming, 1 inch oak
is no party to bend. Lastly, always wear protective eyewear and
optional other safety gear when working with steam, wood, fire, etc.
Good luck and move quickly and in a predetermined manner and you
should be fine.

On Mon, 25 Jun 2007 07:36:45 -0700, Todd wrote:

A piece of 1" red oak can be bent to radius of 1" if supported by a
metal strap and 11.5" unsupported according to "wood Bending Handbook"
published by Woodcraft Supply. That sounds about right to me as long
as the strap is fixed at both ends so that the neutral axis is pushed
to the outer radius. Also, remember that it is primarily the heat that
plasticizes wood and that you do not gain any additional softening by
heating the wood beyond the boiling point of water. Luthiers use dry
heat as did barrel makers. I have never had very good results from
simply getting the work piece wet, it must get hot.

If you need to do further testing for your application before building
a steam box you can try boiling the piece of wood or wrapping the
section that you need to bend in rags and pour lots and lots of
boiling water over the rags.

Leverage helps but does not prevent breaking or crushing the grain on
the inner radius. Bending over matched male and female forms with
plenty of clamps does help.


Back when I lived on the coast of Maine I helped with the rebuilding
of a 40 ft. dragger under the supervision of an 80 years old boat
builder. We were replacing 4 X 4 inch ribs.

The ribs were made from green oak or at least not seasoned for years
and years. They were sliced down the middle for all but the butt where
they mortised into the keel timbers. Then they were boiled. A long
piece of large pipe sat at an angle with one end in a fire. The pipe
held three or four ribs and was full of soapy water (I have no idea
why soapy water was better). We boiled them for a while and then bent
them into the forms. If they didn't seem limber enough we took them
out and boiled them some more.

It was all new to me but the 80 year old boat builder didn't seem to
think it was anything out of the ordinary.




Bruce in Bangkok
(brucepaigeatgmaildotcom)

--
Posted via a free Usenet account from http://www.teranews.com

On Jun 25, 10:03 am, wrote:
On Jun 25, 10:36 am, Todd wrote:

A piece of 1" red oak can be bent to radius of 1" if supported by a
metal strap and 11.5" unsupported according to "wood Bending Handbook"
published by Woodcraft Supply.

I think you meant that one inch oak can be bent to a radius of one
foot! I am sure most caught that though.


Nope, the book says 1" or 25 millimeters. Unsupported it's 11.5
inches. (My experience is that a radius of 1 foot is achievable with
out the metal strap support.) I'll grant you that it seems impossible
and I'm looking for another source in my office but I can't put my
hands on it just now. I know that Thonet did some very impressive
bending in the chairs he made. The book states that these are the
results of tests done on air-dried steamed material 1 inch (25.4 mm)
thick. Part of the "support" they refer to is that the work piece is
attached to a metal strap on the outer surface that is clamped to the
work piece by applying clamping pressure on the ends of the pieces,
i.e. the clamp faces are pressing on the end grain face of each end,
this is critical for this kind of bending. It is not just having a
"backing" strap. Clamping pressure must be applied to the end grain
faces as the piece is bent.