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MarshallE
Guest
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 Posted: Fri Jun 22, 2007 6:32 am Post subject: Newbie trying to Steam Bend Oak 1" thick x 3" wide |
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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 |
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Lew Hodgett
Guest
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| Posted: Fri Jun 22, 2007 6:32 am Post subject: Re: Newbie trying to Steam Bend Oak 1" thick x 3" wide |
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MarshallE wrote:
| Quote: | 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 |
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Jim Northey
Guest
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| Posted: Fri Jun 22, 2007 6:32 am Post subject: Re: Newbie trying to Steam Bend Oak 1" thick x 3" wide |
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"MarshallE" <meakes@triad.rr.com> wrote in message
news:1182480637.382122.305460@e9g2000prf.googlegroups.com...
| Quote: | 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 |
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Brian Nystrom
Guest
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| Posted: Thu Jun 28, 2007 7:27 pm Post subject: Re: Newbie trying to Steam Bend Oak 1" thick x 3" wide |
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justwaitafrekinminute@gmail.com wrote:
| Quote: | On Jun 25, 10:36 am, Todd <tfill...@execpc.com> 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.
|
No the original post is correct.
| Quote: | 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.
|
Nope. If you get it too WET, it will crush and/or tear. If you heat it
too much, it drives off the moisture in the wood and it becomes brittle.
The typical failure mode it a sharp break.
| Quote: | 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.
|
The whole point of using steam is that it heats the wood quickly and
evenly to a consistent temperature, the boiling point of water
(100C/212F). The moisture helps to carry and transfer heat more
efficiently than dry air does.
| Quote: | 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.
A note. Once wood has been steamed once, the cells will not soften
again with heat.
|
Not exactly. As long as it has been steamed, it can be re-steamed. If
you heat it any higher, such as is done during kiln drying, it alters
the lignin in the wood and make bending it more difficult. However, I've
seen good bending results with kiln-dried oak that was subsequently
steamed, but you can't achieve as small a bend radius with it.
| Quote: | 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.
|
This is a common myth that is pure bunk. It takes ~1 hour to heat 1"
thick wood sufficiently in a steam box, so there's no way that it can
cool enough in a few seconds to make any difference in how it bends. In
fact, one of the biggest causes for failures/breakage during steam
bending is rushing it. It takes a little time for the fibers in the wood
to slip and the thicker the wood, the more time it takes. Bending
should be done smoothly, deliberately and as quickly as the wood will
allow, but you have a LOT more than a few seconds to bend it. |
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Guest
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| Posted: Fri Jun 29, 2007 7:06 am Post subject: Re: Newbie trying to Steam Bend Oak 1" thick x 3" wide |
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On Jun 28, 10:27 am, Brian Nystrom <brian.nyst...@verizon.net> wrote:
| Quote: | justwaitafrekinmin...@gmail.com wrote:
On Jun 25, 10:36 am, Todd <tfill...@execpc.com> 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.
No the original post is correct.
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.
Nope. If you get it too WET, it will crush and/or tear. If you heat it
too much, it drives off the moisture in the wood and it becomes brittle.
The typical failure mode it a sharp break.
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.
The whole point of using steam is that it heats the wood quickly and
evenly to a consistent temperature, the boiling point of water
(100C/212F). The moisture helps to carry and transfer heat more
efficiently than dry air does.
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.
A note. Once wood has been steamed once, the cells will not soften
again with heat.
Not exactly. As long as it has been steamed, it can be re-steamed. If
you heat it any higher, such as is done during kiln drying, it alters
the lignin in the wood and make bending it more difficult. However, I've
seen good bending results with kiln-dried oak that was subsequently
steamed, but you can't achieve as small a bend radius with it.
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.
This is a common myth that is pure bunk. It takes ~1 hour to heat 1"
thick wood sufficiently in a steam box, so there's no way that it can
cool enough in a few seconds to make any difference in how it bends. In
fact, one of the biggest causes for failures/breakage during steam
bending is rushing it. It takes a little time for the fibers in the wood
to slip and the thicker the wood, the more time it takes. Bending
should be done smoothly, deliberately and as quickly as the wood will
allow, but you have a LOT more than a few seconds to bend it.
|
Now I will disagree with you. I have several steam boxes and have
steamed a lot of oak and other lumber... But I will let the OP make
the call. Nice to see you again Brian. |
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Brian Whatcott
Guest
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| Posted: Sat Jun 30, 2007 5:54 am Post subject: Re: Newbie trying to Steam Bend Oak 1" thick x 3" wide |
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On Sun, 24 Jun 2007 02:19:52 GMT, Brian Nystrom
<brian.nystrom@verizon.net> wrote:
| Quote: | justwaitafrekinminute@gmail.com wrote:
....
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.
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Talking of alternatives - nobody mentioned the cold water method in
tihs incarnation of the wood bending thread - which is reputed to turn
planks to spaghetti:
add ammonia - soak overnight.
Disclaimers:
1) not tried it.
2) may take some of the beef out of the wood.
Brian Whatcott Altus OK |
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cavelamb himself
Guest
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| Posted: Sat Jun 30, 2007 11:26 am Post subject: Re: Newbie trying to Steam Bend Oak 1" thick x 3" wide |
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Brian Whatcott wrote:
| Quote: | On Sun, 24 Jun 2007 02:19:52 GMT, Brian Nystrom
brian.nystrom@verizon.net> wrote:
justwaitafrekinminute@gmail.com wrote:
...
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.
Talking of alternatives - nobody mentioned the cold water method in
tihs incarnation of the wood bending thread - which is reputed to turn
planks to spaghetti:
add ammonia - soak overnight.
Disclaimers:
1) not tried it.
2) may take some of the beef out of the wood.
Brian Whatcott Altus OK
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They do not recover full strength after ammonia... |
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Brian Nystrom
Guest
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| Posted: Sat Jun 30, 2007 3:57 pm Post subject: Re: Newbie trying to Steam Bend Oak 1" thick x 3" wide |
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cavelamb himself wrote:
| Quote: | Brian Whatcott wrote:
On Sun, 24 Jun 2007 02:19:52 GMT, Brian Nystrom
brian.nystrom@verizon.net> wrote:
justwaitafrekinminute@gmail.com wrote:
...
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.
Talking of alternatives - nobody mentioned the cold water method in
tihs incarnation of the wood bending thread - which is reputed to turn
planks to spaghetti:
add ammonia - soak overnight.
Disclaimers:
1) not tried it.
2) may take some of the beef out of the wood.
Brian Whatcott Altus OK
They do not recover full strength after ammonia...
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And it's noxious to work with. No thanks. |
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