OK, I have a project in mind and its going to involve steam bending some timber.
What I need is cheap ideas for building a small unit that I can steam stuff in!
I already plan on using a wallpaper steamer to provide the steam and the unit doesn't have to be bigger than 4" across and 4' long.
Many thanks
I've also been planning on doing some steam bending, and have no experience
whatever with the process. What I do have is a steam unit called a
"Ladybug". It is a semi profesional unit, which generates a smaller quantity
of very high temperature steam.
My question is....... Which is the better condition for bending wood, High
temperature with low moisture content, or lower temperature with more
moisture? What is the best temperature range for bending wood, and what is
the best moisture content? Should I pre-soak the wood before I place it in
the steamer, or just start with dry wood, and rely mainly on the temperature
to make the wood pliable?
Anyone have any thoughts or experience with this?
--
Offered in the spirit of friendship and respect :)
Kevin
TrailRat wrote:
...
> I already plan on using a wallpaper steamer to provide the steam and
the unit doesn't have to be bigger than 4" across and 4' long.
...
Not familiar w/ the actual output of those steamers so can't comment on
the volume or all but there are many plans that just use PVC for the
basic volume...
--
RE: Subject
A little basic heat transfer.
To raise temperature of 1# water 1 degreeF requires 1 BTU.
Thus 180 BTU/# of water are required to raise the temperature from 32F
to 212F.
To convert 1# of 212F water to 1# of 212F steam requires 144BTU/#.
This is known as the "Heat of vaporization".
To raise the temperature of steam above 212F requires 1BTU/#, and
requires the steam to be above atmospheric pressure.
This is known as super heated steam and forms the basis of every
fossil fueled electric steam powered generating station.
(Damn, you never forget that stuff.)
More the 50 years ago, passed the Ohio PE exam solving heat transfer
problems.
All of which has very little to do with most steam bending rigs for
wood.
The steam in the steaming chamber is at atmospheric pressure and will
be 212F.
BTW, I have always been told to use "green" lumber for steam bending.
YMMV.
Lew
On 6/29/2011 10:11 PM, [email protected] wrote:
> On Wed, 29 Jun 2011 11:41:11 -0400, Digger <[email protected]>
> wrote:
>
>> On 6/29/2011 9:47 AM, [email protected] wrote:
>>> I've also been planning on doing some steam bending, and have no experience
>>> whatever with the process. What I do have is a steam unit called a
>>> "Ladybug". It is a semi profesional unit, which generates a smaller quantity
>>> of very high temperature steam.
>>>
>>> My question is....... Which is the better condition for bending wood, High
>>> temperature with low moisture content, or lower temperature with more
>>> moisture? What is the best temperature range for bending wood, and what is
>>> the best moisture content? Should I pre-soak the wood before I place it in
>>> the steamer, or just start with dry wood, and rely mainly on the temperature
>>> to make the wood pliable?
>>>
>>> Anyone have any thoughts or experience with this?
>>>
>>
<snip>
>>
>> My thought, and again I am not a fluid physics major, is that steam is
>> 212 deg F, period! Unless one uses some sort of additional process,
>> pressure and super heating, to force higher temperatures (danger Will
>> Robinson), steam remains steam and the temperature is relative only to
>> the type and design of generator used. Water boils at a 212 deg, which
>> remains fairly constant in free space at sea level. Volume (or density)
>> of steam produced is a whole different discussion and would vary with
>> type and settings of burner combined with method of containment and
>> surface exposure.
>>
> Nothing stops steam from exceding 212F. WATER cannot exist above 212
> at normal atmospheric temperature, but it is possible to produce steam
> over 350F
Never said steam could not be heated to higher temps, but, as stated
above, it would take additional effort to achieve elevated temperatures.
As water boils at 212, steam is (theoretically at least) immediately
directed to the containment vessel due to venting, without additional
heating or other post process. We are talking about the simplest form of
a steam genny aren't we? But, perhaps I am wrong.
<snip>
>>
>> One can soak stock in a body of water for months and probably achieve
>> almost the same capability of radius bend as steam, but the whole point
>> of using steam is speed. I see no advantage to pre-soak and would think
>> it might add weeks to fixing/ curing. Just my best guess, but I do know
>> it takes much longer for water soaked lumber to dry and become workable
>> again than simple steaming. My sense is stick with cured lumber.
>
> Another time proven method of bending wood is "hot pipe" bending - and
> there you DO soak the wood - the roughly 300 F heat of the hot pipe
> turns the water in the wood to steam. It is the heat, more than the
> moisture, that allows the wood to bend, as it loosens the lignen? in
> the fibers, allowing them to slip.
>
Not familiar with "hot pipe" process as such -- perhaps an aka might
ring a bell -- and have only played with the simplest forms of steam
bending. Sounds logical though, but more like a commercial process
rather than homebrew backyard project. However, never too late for me to
learn something new.<g> Keep in mind, yours truly is only a hobbyist at
best, not a pro or expert.
Cheers,
--
Digger
Bob O'Dell
<[email protected]> wrote
> I've also been planning on doing some steam bending, and have no
> experience
> whatever with the process. What I do have is a steam unit called a
> "Ladybug". It is a semi profesional unit, which generates a smaller
> quantity
> of very high temperature steam.
>
> My question is....... Which is the better condition for bending wood, High
> temperature with low moisture content, or lower temperature with more
> moisture?
According to the Uk Forest Products Wood Bending Handbook, 'wood at 25% -
30% moisture content contains enough moisture as is necessary to render it
compressible when heated.'
'Wood is in the best possible condition for bending when it has been heated
right through to boiling point.'
'........for the most part the effect of steaming is to heat the wood, not
to inject steam into material as is sometimes supposed.'
Jeff
--
Jeff Gorman, West Yorkshire, UK
email : Username is amgron
ISP is clara.co.uk
www.amgron.clara.net
In article <3cb411e5-14ff-4b66-bc85-55951b4bc6a3
@glegroupsg2000goo.googlegroups.com>, [email protected] says...
> OK, I have a project in mind and its going to involve steam bending some timber.
>
> What I need is cheap ideas for building a small unit that I can steam stuff in!
>
> I already plan on using a wallpaper steamer to provide the steam and the unit
> doesn't have to be bigger than 4" across and 4' long.
>
> Many thanks
Double boiler?
Pot with a vegetable steamer to keep the wood away from the water.
In article <[email protected]>, [email protected]
says...
> In article <3cb411e5-14ff-4b66-bc85-55951b4bc6a3
> @glegroupsg2000goo.googlegroups.com>, [email protected] says...
> > OK, I have a project in mind and its going to involve steam bending some timber.
> >
> > What I need is cheap ideas for building a small unit that I can steam stuff in!
> >
> > I already plan on using a wallpaper steamer to provide the steam and the unit
> > doesn't have to be bigger than 4" across and 4' long.
> >
> > Many thanks
>
> Double boiler?
>
> Pot with a vegetable steamer to keep the wood away from the water.
>
Oops.
Aging eyes misread the post this morning and saw inches instead of feet.
Gotta get a new prescription.
Armed with all this new information, I contacted the manufacturer of my
LadyBug Steam Cleaner. I was assured that the steam leaving the boiler is at
290Degrees, but cools slightly as it travels through the delivery hose. The
main question now is the amount of thermal gain required to heat a given
size chamber, the efficiency of the chamber's insulation, and the method of
distribution within the chamber. I had no idea I was entering into a physics
dilemma! I was also told that the machine is intended for cleaning with
superheated steam, rather than what I plan to use it for. Does a good job
cleaning, so why not see if the little "Bug" is up to the test.
I'm just going to make a test chamber with pvc pipe, insulate the heck out
of it, measure the temperature of the exhaust, and do a few trial runs.
Nothing ventured, nothing gained. I'll try to remember to post my results
when I get around to doing the test. If it works, I can imagine that more
than one Steam Cleaner is going to find it's way out of the vacuum cleaner
closet, and into the workshop! :)
Kevin
On 6/28/2011 9:39 AM, TrailRat wrote:
> OK, I have a project in mind and its going to involve steam bending some timber.
>
> What I need is cheap ideas for building a small unit that I can steam stuff in!
>
> I already plan on using a wallpaper steamer to provide the steam and the unit doesn't have to be bigger than 4" across and 4' long.
>
> Many thanks
Might grab a piece of 4-6" dia schedule-40 PVC pipe (schedule-80 is even
better), cap one end using PVC glue (do not use threaded pvc joints at
these temps) and slip cap the other. Drill and tap the center of the
pipe tube for a connection to your homemade steam genny. Drill a few
evenly distributed holes in the top (1/8 - 3/16) for pressure relief,
and add a ball valve at fixed end to serve as drain and added safety valve.
Open slip cap (cover), insert stock, replace slip cap, open steam input
valve for 30-40 minutes and check for doneness. Use heavy barbecue
gloves, tongs, and wear thick clothing and eye protection. Warning!! Do
not stand in front of removable slip cap while cooking or removing cap
cover.
Simple, cheap, can be varying lengths/ widths to accommodate stock
sizes. Easily mounted at slight down angle (to facilitate draining of
condensed water) on upright cinder block or just about any sort of home
brewed support. Should safely handle temps up to about 140 deg. F; steam
is much higher in temp, but with low pressures, adequate venting, and
ambient external skin temperatures the pipe won't exceed its maximum. If
concerned, add an inexpensive temp gauge and monitor aggressively.<G>
--
Digger
Bob O'Dell
On 6/29/2011 9:47 AM, [email protected] wrote:
> I've also been planning on doing some steam bending, and have no experience
> whatever with the process. What I do have is a steam unit called a
> "Ladybug". It is a semi profesional unit, which generates a smaller quantity
> of very high temperature steam.
>
> My question is....... Which is the better condition for bending wood, High
> temperature with low moisture content, or lower temperature with more
> moisture? What is the best temperature range for bending wood, and what is
> the best moisture content? Should I pre-soak the wood before I place it in
> the steamer, or just start with dry wood, and rely mainly on the temperature
> to make the wood pliable?
>
> Anyone have any thoughts or experience with this?
>
I am no expert!! So, I can only express an opinion based upon my own
limited experiments...
My thought, and again I am not a fluid physics major, is that steam is
212 deg F, period! Unless one uses some sort of additional process,
pressure and super heating, to force higher temperatures (danger Will
Robinson), steam remains steam and the temperature is relative only to
the type and design of generator used. Water boils at a 212 deg, which
remains fairly constant in free space at sea level. Volume (or density)
of steam produced is a whole different discussion and would vary with
type and settings of burner combined with method of containment and
surface exposure.
So, I would think, simply brainstorming for discussion, that given a
relatively fixed temp, moisture content and absorption rates become a
function of time, exposed surface area and pressure, variables easily
controlled. Rates will also differ based upon cellular density and stock
sizes; hardwood vs soft pine...open porous stock vs close grain etc.
One can soak stock in a body of water for months and probably achieve
almost the same capability of radius bend as steam, but the whole point
of using steam is speed. I see no advantage to pre-soak and would think
it might add weeks to fixing/ curing. Just my best guess, but I do know
it takes much longer for water soaked lumber to dry and become workable
again than simple steaming. My sense is stick with cured lumber.
--
Digger
Bob O'Dell
On 6/28/2011 2:27 PM, Edward A. Falk wrote:
> In article <[email protected]>,
> Digger <[email protected]> wrote:
>
>> Might grab a piece of 4-6" dia schedule-40 PVC pipe (schedule-80 is even
>> better), cap one end using PVC glue (do not use threaded pvc joints at
>> these temps) and slip cap the other. Drill and tap the center of the
>> pipe tube for a connection to your homemade steam genny.
>
> This is roughly what I was planning to do for my own project.
>
> What's a quick-n-dirty design for a steam generator? I was thinking
> in terms of a cooking pot with a lid formed of tinfoil wrapping around
> a hose. That's probably not a very good design.
>
Lobster cooker (or fry cooker) and perhaps a high quality galvanized
gasoline can of at least 5 gal or more; preferably new and unused. :-)
Some flexible radiator styled hose, clamps, and off the shelf pipe
fittings should about do it.
New Yankee Workshop did a program using a similar homebrew (the subject
was some sort of hat rack), might still be available from their website.
I believe they primarily used ABS plastic pipe, which is coded to 180
deg F, and exceeds the 140 degs of PVC.
Essentially one simply joins two lengths of 4-6" pipe together with a
"Tee". Steam from the boiler is injected at the Tee. The slip cap cover
would also benefit from some sort of homebrew handle, which makes it
easier to grip and remove safely.
Pressure can really build quickly so, I would recommend experimenting
with your ball valve settings to find the best balance. Their is no way
for me to know how big, how much pressure, or temperatures your own
construct will generate so be smart, and please try not to fire the end
cap through a neighbors picture window.
good luck,
--
Digger
Bob O'Dell
On Jun 28, 9:39=A0am, TrailRat <[email protected]> wrote:
>
> OK, I have a project in mind and its going to involve steam bending some =
timber.
>
> What I need is cheap ideas for building a small unit that I can steam stu=
ff in!
>
> I already plan on using a wallpaper steamer to provide the steam and the =
unit doesn't have to be bigger than 4" across and 4' long.
You could use 4' sections of snap-together galvanized round ductwork
with a couple of end caps. Wrap the duct in scrap rebond carpet
padding for insulation. You want the steam to circulate around the
wood, so use some scrap wood to make a ladder-arrangement that will
slide inside the duct and raise the wood to be steamed so it's not
touching the duct.
R
"Digger" <[email protected]> wrote
> Might grab a piece of 4-6" dia schedule-40 PVC pipe (schedule-80 is even
> better), cap one end using PVC glue (do not use threaded pvc joints at
> these temps) and slip cap the other. ......................
I've found that it helps if you insulate the tube.
And to prevent condensation onto the tools, do it outside the workshop!
Jeff
--
Jeff Gorman, West Yorkshire, UK
email : Username is amgron
ISP is clara.co.uk
www.amgron.clara.net
In article <[email protected]>,
Digger <[email protected]> wrote:
>Might grab a piece of 4-6" dia schedule-40 PVC pipe (schedule-80 is even
>better), cap one end using PVC glue (do not use threaded pvc joints at
>these temps) and slip cap the other. Drill and tap the center of the
>pipe tube for a connection to your homemade steam genny.
This is roughly what I was planning to do for my own project.
What's a quick-n-dirty design for a steam generator? I was thinking
in terms of a cooking pot with a lid formed of tinfoil wrapping around
a hose. That's probably not a very good design.
--
-Ed Falk, [email protected]
http://thespamdiaries.blogspot.com/
"TrailRat" wrote in message
news:3cb411e5-14ff-4b66-bc85-55951b4bc6a3@glegroupsg2000goo.googlegroups.com...
OK, I have a project in mind and its going to involve steam bending some
timber.
What I need is cheap ideas for building a small unit that I can steam stuff
in!
I already plan on using a wallpaper steamer to provide the steam and the
unit doesn't have to be bigger than 4" across and 4' long.
Many thanks
=======================
You wife always wanted one of those hanging clothes steamers anyway. They
work like a charm!
--
Eric
On Tue, 28 Jun 2011 18:27:26 +0000 (UTC), [email protected] (Edward A.
Falk) wrote:
>In article <[email protected]>,
>Digger <[email protected]> wrote:
>
>>Might grab a piece of 4-6" dia schedule-40 PVC pipe (schedule-80 is even
>>better), cap one end using PVC glue (do not use threaded pvc joints at
>>these temps) and slip cap the other. Drill and tap the center of the
>>pipe tube for a connection to your homemade steam genny.
>
>This is roughly what I was planning to do for my own project.
>
>What's a quick-n-dirty design for a steam generator? I was thinking
>in terms of a cooking pot with a lid formed of tinfoil wrapping around
>a hose. That's probably not a very good design.
Lee Valley used to sell an electric tea kettle for use as a steam
generator.
See page 6 of the below PDF file.
http://www.leevalley.com/US/html/05F1501ie.pdf
--
Jack Novak
Buffalo, NY - USA
On Wed, 29 Jun 2011 11:41:11 -0400, Digger <[email protected]>
wrote:
>On 6/29/2011 9:47 AM, [email protected] wrote:
>> I've also been planning on doing some steam bending, and have no experience
>> whatever with the process. What I do have is a steam unit called a
>> "Ladybug". It is a semi profesional unit, which generates a smaller quantity
>> of very high temperature steam.
>>
>> My question is....... Which is the better condition for bending wood, High
>> temperature with low moisture content, or lower temperature with more
>> moisture? What is the best temperature range for bending wood, and what is
>> the best moisture content? Should I pre-soak the wood before I place it in
>> the steamer, or just start with dry wood, and rely mainly on the temperature
>> to make the wood pliable?
>>
>> Anyone have any thoughts or experience with this?
>>
>
>I am no expert!! So, I can only express an opinion based upon my own
>limited experiments...
>
>My thought, and again I am not a fluid physics major, is that steam is
>212 deg F, period! Unless one uses some sort of additional process,
>pressure and super heating, to force higher temperatures (danger Will
>Robinson), steam remains steam and the temperature is relative only to
>the type and design of generator used. Water boils at a 212 deg, which
>remains fairly constant in free space at sea level. Volume (or density)
>of steam produced is a whole different discussion and would vary with
>type and settings of burner combined with method of containment and
>surface exposure.
>
Nothing stops steam from exceding 212F. WATER cannot exist above 212
at normal atmospheric temperature, but it is possible to produce steam
over 350F
>So, I would think, simply brainstorming for discussion, that given a
>relatively fixed temp, moisture content and absorption rates become a
>function of time, exposed surface area and pressure, variables easily
>controlled. Rates will also differ based upon cellular density and stock
>sizes; hardwood vs soft pine...open porous stock vs close grain etc.
>
>One can soak stock in a body of water for months and probably achieve
>almost the same capability of radius bend as steam, but the whole point
>of using steam is speed. I see no advantage to pre-soak and would think
>it might add weeks to fixing/ curing. Just my best guess, but I do know
>it takes much longer for water soaked lumber to dry and become workable
>again than simple steaming. My sense is stick with cured lumber.
Another time proven method of bending wood is "hot pipe" bending - and
there you DO soak the wood - the roughly 300 F heat of the hot pipe
turns the water in the wood to steam. It is the heat, more than the
moisture, that allows the wood to bend, as it loosens the lignen? in
the fibers, allowing them to slip.