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#1
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Steaming!
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 |
#2
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Steaming!
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... -- |
#3
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Steaming!
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 |
#5
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Steaming!
On 6/28/2011 2:27 PM, Edward A. Falk wrote:
In article , Digger 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 |
#6
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Steaming!
"TrailRat" wrote in message
... 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 |
#7
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Steaming!
"Digger" 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 |
#8
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Steaming Conditions
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 |
#9
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Steaming Conditions
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#10
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Steaming Conditions
On Wed, 29 Jun 2011 11:41:11 -0400, Digger
wrote: On 6/29/2011 9:47 AM, 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. |
#11
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Steaming Conditions
On 6/29/2011 10:11 PM, wrote:
On Wed, 29 Jun 2011 11:41:11 -0400, Digger wrote: On 6/29/2011 9:47 AM, 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 |
#12
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Steaming Conditions
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 |
#13
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Steaming Conditions
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 |
#14
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Steaming!
In article 3cb411e5-14ff-4b66-bc85-55951b4bc6a3
@glegroupsg2000goo.googlegroups.com, 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. |
#15
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Steaming!
In article ,
says... In article 3cb411e5-14ff-4b66-bc85-55951b4bc6a3 @glegroupsg2000goo.googlegroups.com, 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. |
#16
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Steaming Conditions
On 6/30/2011 2:02 AM, Lew Hodgett wrote:
The steam in the steaming chamber is at atmospheric pressure and will be 212F. Ok, good deal. I feel much better now! Thanks for the clarification Lew, -- Digger Bob O'Dell |
#17
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Steaming!
On Jun 28, 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. 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 |
#18
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Steaming Conditions
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 |
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