Steaming Techniques.

Discussion in 'Wooden Boat Building and Restoration' started by djwkd, Mar 17, 2008.

  1. djwkd
    Joined: Jul 2006
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    djwkd Senior Member

    Ok-im rebuilding a boat i made a while ago out of some scrap wood and a binbag in about 2 hours.It only has about a half foot draft so i'm gonna up that to about 1.5'.I've fixed the floor already and need to put it back on to the sides by making some mini-ribs.What is the cheapest and easiest way to steam the ribs.(i don't have a steam-cleaner a steambox for this job.)

    I've seen on ray mears bushcraft that you can Douse it with hot water-how hot must the water be???

    Thanks,dominic.
     
  2. TeddyDiver
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    TeddyDiver Gollywobbler

    Didn't understand what you excactly doing but how about a tea pot, a tube or a hose and some duck tape.. Anyway doing something mini...
     
  3. PAR
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    PAR Yacht Designer/Builder

    Use an old metal gas can (preferably without fuel still in it) and build a fire under it. Place the filler neck into a piece of large diameter pipe (PVC, iron, chimney, etc.), though a fitted piece of wood that plugs the pipe (except for the hole to receive the filler neck). Mount the pipe at a slight angle, say 5 degrees with the filler neck on the lower end. Soak your wood over night in water, then place inside the pipe on some small stands to keep it off the pipe walls. Start you fire, fill the can with water and drape a heavy, soaking wet towel over the open end of the pipe. Steam will build up and rise into the pipe, captured by the wet towel. Lots of steam will escape, so a few towels will help. Cook an hour (after a full head of steam is working) for each 1" of thickness your lumber is.

    Boiling water will often be all you need, if the radius isn't too severe. Drape towels over the wood, then soak them with boiling water. You'll be doing this as you're "talking" them into position on the boat or bending jig.

    Of course only very straight grained lumber should be considered, preferably quite green (freshly cut).
     
  4. longliner45
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    longliner45 Senior Member

    for every inch of thickness ,,you will need one hr of steam time,,,,,you can use a electric element and pipe,place your element in a resevoir,,and make a channel to the box,it can be controlled easely from there,longliner,per lazyjack
     
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  5. djwkd
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    djwkd Senior Member

    Thanks everyone.The probken with longliners theory (the one that sounds easiest)is that the nearest resevoir is about 50 miles from where i live :(.I tried using a kettle before posting this and doused the wood with the boiling water from it,but it didn't work.I bent the wood to the shape i needed but it snapped.Oh well.IS there any reccomendations for a good steaming wood, Or just green wood?

    Thanks,dominic.
     
  6. Landlubber
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    Landlubber Senior Member

    djwkd,

    The wood does not have to be green my friend, seasoned wood goes soggy too.
     
  7. PAR
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    PAR Yacht Designer/Builder

    The choices in order of preference are: green, partial naturally seasoned, fully naturally seasoned and lastly kiln dried. Any wood can be bent, though breakage will be progressively higher on less desirable species and the type (and amount) of drying.

    White oak is a common timber used for bending, live oak (my preference), alder, ash and a few others are reasonably common. Besides the ability to accept bending, other considerations are the ability to accept fasteners, rot resistance and of course the physical properties necessary for the tasks asked of it as a framing material.

    Splashing boiling water on dry stock usually will not do much, the wood has to be soaked with boiling water, which is why steaming is done. How tight is the smallest radius? The dimensions of the stock, moisture content, drying method and species? Some woods just don't like to bend much.
     
  8. Eagle Boats
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    Eagle Boats Senior Member

    A very timely thread as I have to build a steam box. Does anyone have any plans? Also, I need to steam teak. For teak, do you still steam it for one hour per inch thickness?
     
  9. PAR
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    PAR Yacht Designer/Builder

    For a small seam box, the best thing I've found, that is easy to find is galvanized sheet metal chimney pipe. It comes in a few different sizes, like 6", 8" 10" diameters, which is fine for a dozen ribs or maybe 8 or 9 deck planks. They can be stacked, end to end with the crimped slip fit design they have, so length isn't a problem. They tolerate the steam without falling apart, don't have to be assembled or caulked and can be broken down into short lengths for storage. I have taped the two lengths of 8" pipe that I have with metal foil tape, but it's not necessary.

    The low end has a custom cut piece of 3/4" plywood to fit snuggly inside the pipe and is taped on with more foil tape. It has a 3/4" diameter drilled in it near the bottom edge. This is the outside diameter of the pipe I use to feed the steam in with. The steam boiler is a 5 gallon metal gas can with a rubber hose for a spout. This is filled about 3/4's with water and placed on one of those big camp site propane cookers. It brings it to a boil in about 25 minutes, but a wood fire could do the same thing. I like the propane cooker because it's a positive shut off and start thing and no stoking.

    The pipe needs to be cocked at an angle, with the receiver end (the end where you insert the lumber) higher then the steam feed end. This insures the steam will rise through the lumber, exiting the top.

    I have another piece of 3/4" plywood disk, which I use as a door at the input end, but it is set on some cheap hinges. Again the door is a snug fit, inside the pipe when closed, but should be loose enough to permit steam to escape, so you don't blow anything up.

    You can go to a lot of trouble building and caulking up a fine wooden steam box, but the pipe box works just as well, is much lighter and will probably out last it by a fair margin.

    I've seen some use thick walled PVC pipe, but I suspect they'll just warp and distort with the heat without continuous length support. I just prop my pipe steamer up on a couple of different height saw houses and call it ready after I bungee cord it down. Fill the can, light the burner and start cooking wood.
     
  10. waikikin
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    waikikin Senior Member

    A small steambox can be made from a length of metal rainwater downpipe used for storm water, I beleive it helps if you wrap some blankets around it- especially if you lean on it! I've got a timber one made out of 3/4 exterior ply, 2 sections at 8' long & 1 at 5' long & around 12" x 12" square(for econemy of constructon), the steam source is an 18 gallon staino beer keg with a big gas ring & shroud under it- goes like a beauty but I lend it now more than use it myself & it also serves as a quick scaffold on a couple of saw horses. All the best from Jeff.
     
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  11. charmc
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    charmc Senior Member

    Dominic,

    If you're joking, I'll look like a dork (won't be the first time :)), but I'll assume you're serious in calling it a problem. Longliner's "resevoir" is any container that will hold the electric heating element (Some prefer electric water heating to open flame; use whichever suits you.). Otherwise, he's saying pretty much the same as PAR and Waikikin. Any way to heat a few gallons of water to make steam, and a tube to vent the steam into a long container big enough to hold some wood pieces, covered but with a way for a bit of steam to escape to prevent pressure buildup and a big bang, and you're good. Keep it simple and leave the wood in a little longer than the minimum, rather than a little less, and you'll have bendable pieces.
     
  12. Landlubber
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    Landlubber Senior Member

    Water turns to steam at 100deg C, if you heat the steam also it becomes "superheated" and penetrates even better and faster.

    Normal steam is good for 150 lbs pressure, so be careful not to cap it off (superheated steam can get to 400 lbs, quite explosive).

    Take care and remember that the wood is seriously hot when you remove it, wear leather gloves and bend it asap after taking from the steam tubes.

    Prepare the job dry, have the clamps etc ready to roll, you do not have a lot of time before the wood cools and sets in place.
     
  13. Landlubber
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    Landlubber Senior Member

    Oh, and superheated steam is invisible, be extra careful if you heat the steam.

    Your skin will simply peel off if it contacts superheated steam.
     

  14. djwkd
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    djwkd Senior Member

    LOL-No i wasn't joking.I thought he meant a resevoir as in a place where they keep fresh water and suplly it to nearby towns.:rolleyes:
     
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