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A pressurized board steamer you can make quickly

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Blog entry by shipwright posted 04-05-2012 10:27 PM 2748 reads 11 times favorited 12 comments Add to Favorites Watch

This entry was prompted by this forum topic. I thought it would be of interest to look at a different kind of steamer that is capable of creating more, hotter steam than the average atmospheric pressure ones that are limited to something around 212 deg. F and less at altitude. I don’t have access to either my rusty (but still trusty) old steamer right now or the photo of it that I know I have at home so I did a quick 2D of it in sketchup.

Several years ago I designed this one to be portable to job sites to replace broken planks and the like on site at tide grids and haul-outs. It will produce steam under pressure and therefore hotter than un-pressurized steam which means boards will steam much faster. This is important when you are replacing a bottom plank on a tide grid and the tide is coming up. I can’t actually remember pressures or temperatures exactly because I always go by the look and sound of the steam. ”If it’s white, it’s right” is a good rule. You can get steam so hot it becomes clear and will simply toast the board and ruin it. I’m not sure this rig would be capable of that or not but just keep an eye out and if the sound suddenly seems to get higher in pitch and the steam looks clear, back off the fire a bit.

The pressure is created by the head of water in the open tank. As the pressure builds the water in the closed tank is pushed down and you will see the water in the open tank rise. It will either reach an equilibrium or the closed tank will empty and start blowing steam out through the water in the open tank. If that happens, you weren’t watching and you are using too much heat. Get the steam you want by adding pressure (water in the open tank) or adding or reducing heat at the tiger torch.

In a pinch this steamer will, from cold water, steam a 1 1/2 ” fir plank sufficiently to be bent into place in less than an hour. It works even better on truly flexible bending woods like green Oak.

An added advantage is that you always have a basin of warm (hot) water to wash your hands.

Thanks for looking in.

Questions and discussion welcome.

Paul

-- Paul M ..............If God wanted us to have fiberglass boats he would have given us fiberglass trees. http://prmdesigns.com/



12 comments so far

View Joe Lyddon's profile

Joe Lyddon

7751 posts in 2717 days


#1 posted 04-05-2012 10:52 PM

Paul,

Wouldn’t the water in the Heated tank seek the level of the water in the Side tank?

Looks unique…

-- Have Fun! Joe Lyddon - Alta Loma, CA USA - Home: http://www.WoodworkStuff.net ... My Small Gallery: http://www.ncwoodworker.net/pp/showgallery.php?ppuser=1389&cat=500"

View shipwright's profile (online now)

shipwright

5000 posts in 1463 days


#2 posted 04-05-2012 11:13 PM

Without the fire Joe, yes it would but as the water in the closed tank builds steam it pushes the level down. The more water in the open tank, the more pressure it has to build to press it down. The more pressure the higher the temperature.
The other factor in this that I didn’t mention is the hose size. I used 1/2” steam hose and it gave enough restriction to make the whole thing work. You could use larger diameter hose and a valve to control the steam release but that just complicates it.
Did I answer your question?

-- Paul M ..............If God wanted us to have fiberglass boats he would have given us fiberglass trees. http://prmdesigns.com/

View Joe Lyddon's profile

Joe Lyddon

7751 posts in 2717 days


#3 posted 04-05-2012 11:30 PM

Yes, Paul, very well!

I was wondering about the steam hose at the top… letting all of the pressure drop as fast as it could be built…

COOL…

Thank you.

-- Have Fun! Joe Lyddon - Alta Loma, CA USA - Home: http://www.WoodworkStuff.net ... My Small Gallery: http://www.ncwoodworker.net/pp/showgallery.php?ppuser=1389&cat=500"

View Trev_Batstone's profile

Trev_Batstone

317 posts in 1158 days


#4 posted 04-06-2012 03:39 AM

Science never was my favorite subject in school.

-- LIVE, LAUGH, CUT WOOD.

View lightweightladylefty's profile

lightweightladylefty

2657 posts in 2378 days


#5 posted 04-06-2012 04:20 AM

Paul,

I’m with Trev! And I’m not especially mechanical either.

Could a pressure canner be converted for this system? I rely completely on my pressure gauge when canning. (I’ve heard too many stories about exploding canners.) I’ve gotten so I know how many minutes it takes at what heat level to get the canner to 11# of pressure (for our elevation) and then maintain it.

I’m seeing an explosion when the 20# propane tank is cut down and fumes are still present. Is that a possibility?

I like the do-it-yourself idea, but I think I’d better leave it to someone who knows what he’s doing! Thanks for sharing your expertise.

L/W

-- Jesus is the ONLY reason for ANY season.

View cathyb's profile

cathyb

757 posts in 1909 days


#6 posted 04-06-2012 06:22 AM

Well…....I must say that it sounds pretty sensible. I do have a little experience with steam bending and I wasn’t very good at it. To begin that journey I made a box on a stand that was about six inches square and six feet long with a towel stuffed in one end and my door on the front. I drilled a hole in the top to add a thermometer to monitor the temperature. The entire box was wrapped with insulation to keep the steam inside my box. My source for steam was an electric tea pot with a hose to the box. It worked pretty well, but I didn’t have any reasonable controls. Initially I was curious to see just which woods would provide the best result. Although it was fun, I gave up on steam bending and moved to bent lamination because it was more dependable. One surprising issue I learned with steaming was that some woods, especially ash, were not particularly thrilled with the steam and became discolored.
Wait a minute is that you I hear chuckling in the background? If I had been a LJ then, I’d probably still be steam bending today…sigh….......
Keep up the good work Paul. You know more than I will ever know in my lifetime, but it sure is great to learn a few things along the way.
Cheers :)

-- cathyb, Hawaii, www.cathyswoodworking.com

View stefang's profile

stefang

13101 posts in 1999 days


#7 posted 04-06-2012 09:23 AM

I have never done any steam bending Paul, but this looks like a very good idea for generating steam for folks who do.

Some years ago we bought a steam cleaning machine that looks like a vacuum cleaner. It was all the rage at the time, but we never found it very useful so it sits on a shelf in my garage. I have thought from time to time that it might be useful as a source of steam for bending wood, but I just haven’t made anything yet that require bent wood. That still doesn’t stop me from wondering if it would be useful.

-- Mike, an American living in Norway.

View KMP Wood Designs's profile

KMP Wood Designs

48 posts in 1313 days


#8 posted 04-06-2012 12:58 PM

Paul,

Do you just spot heat the area that you want to bend or do you put the plank in a box using the hose to fill it to control the amount of steam loss?

-- Jim, Virginia, http://mysite.verizon.net/vzexvdsv/

View rkober's profile

rkober

127 posts in 958 days


#9 posted 04-06-2012 03:16 PM

Paul:
I like it. As a mechanical engineer I started to get worried when I read “creating more, hotter steam than the average atmospheric pressure ones”. However your design does indeed provide controlled pressure but yet a relief for excessive steam pressure. It’s worth noting that you are adding a very low pressure (compared to say a 20# pressure cooker) with the water head. For example, a 12” column of water only adds less than .5 psi.

-- Ray - Spokane, WA - “Most people don’t recognize opportunity because it’s usually disguised as hard work.” - Unknown

View shipwright's profile (online now)

shipwright

5000 posts in 1463 days


#10 posted 04-06-2012 04:00 PM

Good questions and comments.

L/W, I would think that trying to convert a pressure cooker would be more trouble than it is worth and as mentioned above, they build a lot of pressure. As for the propane tank exploding, there are lots of ways to make them safe to work on. If you were really cautious you might fill it with water and drill the holes without even emptying it first.

Cathy, Maybe just a wee little chuckle.

Jim, You lead the hose to a steam box and surround the wood with a constant stream of fresh hot steam.

rkober, As not a mechanical engineer, I’m glad you approve. I’m more of a common sense person. As you work with this little rig you can easily see that while it does build pressure and produce higher temperatures, it is easy to control and has built in pressure relief.

Thanks for the comments.

-- Paul M ..............If God wanted us to have fiberglass boats he would have given us fiberglass trees. http://prmdesigns.com/

View kizerpea's profile

kizerpea

746 posts in 1033 days


#11 posted 04-08-2012 12:11 AM

great minds think alike….i had to bend a board for a bed head board a year ago..i took a propane tank an screwed the valve out put in 2gal of water an screwed in a 3/4 pipe reduced that to 1/2 an used a 8in by 10ft galv duct fired up the propane burner an went to steaming..

-- IF YOUR NOT MAKING DUST...YOU ARE COLLECTING IT! SOUTH CAROLINA.

View rance's profile

rance

4135 posts in 1826 days


#12 posted 04-09-2012 02:05 PM

All good information to know. Thanks for sharing.

Nice drawing too Paul. Only thing I would suggest is to always crop the sides as much as possible to make it show up bigger. LJ seems to always limit their width.

-- Backer boards, stop blocks, build oversized, and never buy a hand plane--

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