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Thread: Bending Oak Without Steam

  1. #1

    Default Bending Oak Without Steam

    Just wondering if anyone has ever tried bending oak with good results using a 50/50 amonia and water mixture ? I need to bend oak trim around the top of my cabin to replace the brow trim on my Catboat.

    Thanks in advance,

    Will

  2. #2
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    Default Re: Bending Oak Without Steam

    I haven't tried it with oak, but I've bent Western Yew with ammonia. Works better than steam.

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    Default Re: Bending Oak Without Steam

    There's a thread on here from several months ago in which the builder of a dacron skinned boat described how he bent the ribs for his boat with ammonia. I don't recall the specie, though.
    Goat Island Skiff and Simmons Sea Skiff construction photos here:

    http://s176.photobucket.com/albums/w...esMan/?start=0

    and here:

    http://www.flickr.com/photos/37973275@N03/

    "All kings are not the same."

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    Default Re: Bending Oak Without Steam

    my experiance is bad with oak. ammonia seems to make it brittle. but thats my experiance

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    Default Re: Bending Oak Without Steam

    I have a friend who says that he bent oak soaked in vinegar.

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    Default Re: Bending Oak Without Steam

    In vinegar ?
    I bet that smells like a old pickle barrel...
    save a nose, pick a banjo

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    Default Re: Bending Oak Without Steam

    I don't know about chemicals, But, soaking the wood in cold water overnight and then wrapping the wood in mattress pads and dousing it with boiling water and letting steep for 20 minutes works to get you most of what steaming will get you.

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    Default Re: Bending Oak Without Steam

    Try heat. Wood is bendable when the core temp gets around 200 deg F, and wood doesn't care what the heat source is, long as the wood moisture content is around 20-25%. I use an industrial heat gun with an exhaust temp high enough to ignite wood, so I gotta keep it in motion. Heat wood, apply bend pressure, and when the wood starts to give you are there!

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    Default Re: Bending Oak Without Steam

    Bending w/ steam is so pleasant...smells good, works great, one of the most fun things about boatbuilding, warms yer hands in winter's cold...ya gotta ask yerself - WHY do you want to put up with the amonia fumes? D'ya have a narcolepsy problem? Or is it just curiosity?
    So, why did you ask?
    But if you insist, what's the 50% water for?

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    Default Re: Bending Oak Without Steam

    Ammonia will allow the wood to bend very freely - even more so than steam. However, the result is a weaker piece of wood. Steam is the best way to go for most boat applications because what you want is something that is strong and not just decorative. In your case, in an application that is not structural, then yes ammonia could be used.
    Last edited by tapsnap; 03-17-2009 at 08:52 PM. Reason: to finish the thought

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    Default Re: Bending Oak Without Steam

    I've heard of boiling strips of wood rather than steaming them -- guess the heat is the key.

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    Default Re: Bending Oak Without Steam

    For a thin solid piece, you can soak it and then run it across something hot (flatiron, stovepipe) while exerting gentle force. The wood needs to be well-soaked and the metal not so hot that it scorches.

    It's a nice way to get a really good-fitting curve. Learned it from a luthier, who used it to get the final form on guitar sides.

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    Default Re: Bending Oak Without Steam

    C'mon guys, give us a reference or more detail on how you have bent wood using ammonia.

    Every reference I have says the procedure requires anhydrous ammonia, which isn't something that can be done in most home shops.

    Otherwise another method without steam is to wrap the bend area tightly in rags, pour on boiling oil and apply heat lamps till the wood reaches 200 degrees F. Takes about 15 minutes at 200 degrees per inch of thickness. And a cooking oil with a high flash point like peanut oil makes a more pleasant job of it than smoky linseed.

    Last edited by Bob Smalser; 03-17-2009 at 09:10 PM.

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    Default Re: Bending Oak Without Steam

    Back when the curved blade hockey stick was invented, they cost about $3.25,twice the normal.On seeing a demonstration of the process, one night, I promptly went to the basement, opened the door of the coal furnace and held my fiberglass stick over the glowing coals. With a bench vise and 3 pieces of broomhandle, I curved my stick. Next day I curved all my buddy's sticks, same fashion,some to rediculous bends. Never broke one. Had no idea I wasn't following the rules.

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    Default Re: Bending Oak Without Steam

    well i don't know about any special kind of ammonia i just followed the instructions i received from another SOF builder and used piersons unscented. worked fine to make the wood bendy (you could tie a knot in it) but the result was brittle when it dried. i wound up replacing all the ribs with brine soaked hazel. all in all i think a better trade.

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    Default Re: Bending Oak Without Steam

    Ammonia bending is done with ammonia gas under pressure. The stuff is extremely effective (it can generate wood strips that can be tied into knots) but is also deadly and has to be used in atightly controlled system. See "Fine Woodworking's" "Bending Wood".
    Somewhere along the line houshold ammonia has come to be seen as a homegrown substitute but the percentage of ammonia involved is so minute it can't possibly have anything but a placibo effect.

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    Default Re: Bending Oak Without Steam

    "Every reference I have says the procedure requires anhydrous ammonia,"

    " household ammonia ... can't possibly have anything but a placebo effect."

    Wise comments.

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    Default Re: Bending Oak Without Steam

    Quote Originally Posted by Bill Huson View Post
    Try heat. Wood is bendable when the core temp gets around 200 deg F, and wood doesn't care what the heat source is, long as the wood moisture content is around 20-25%. I use an industrial heat gun with an exhaust temp high enough to ignite wood, so I gotta keep it in motion. Heat wood, apply bend pressure, and when the wood starts to give you are there!
    Bending with heat has other advantages. The wood is not deformed as thinner strips sometimes are with water. The bent piece experiences very little relaxation after removing from the heat. Luthiers bend the sides of violins, guitars, etc this way. They typically use a hot pipe to bend the wood over and can bend a bit, check against a template and move on until the desired shape is achieved. End result is far better than can be achieved with steam or water soak..
    Tom L

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    Default Re: Bending Oak Without Steam

    One other note: ammonia will darken the oak, a common practice in my field- furniture making.

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    Default Re: Bending Oak Without Steam

    On page #102 of WoodenBoat issue 206,Lowells Boat Shop explains an alternative method. It still involves water,but sounds like the ticket for small stuff. Vinny

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    Default Re: Bending Oak Without Steam

    Boatbuilders in southern India use a method that sounds a bit like what Bob Smalser was talking about with the hot oil wrap. They bend planks to sew together with cord / vine by coating the plank stock liberally with cashew oil, which has a high smoking point, and is locally available and then use an open fire to heat the wood until it's pliable enough to bend to the necessary curves. Boats I saw had planking on the order of 2" thick bent with this method.

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    Default Re: Bending Oak Without Steam

    To bend you need to have air dry (however dry) oak. For most trim bends you should not need to steam or use any of the above methods. Half green you should have no trouble at all. For any method you need reasonably straight grain with no short runouts in the sections with appreciable bending.

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    Default Re: Bending Oak Without Steam

    Quote Originally Posted by ToddFwbf View Post
    One other note: ammonia will darken the oak, a common practice in my field- furniture making.
    This is true - if you've ever gone into a cow barn with Oak beams you will notice they are all black - it's from all that ammonia in the air.

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    Default Re: Bending Oak Without Steam

    i have used linseed oil painted on the day before and a blowlamp just enough to make the oil bubble to get rubbing strakes on when the boat was on a mooring in a well out of the way place working from a small rowboat, in poor weather ,i get all the good jobs , the job went better than i deserved.

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    Default Re: Bending Oak Without Steam

    I have a little different questsion. I gutted the head on my taylor today, and have to replace at least two [ I wanna call em rafters real bad, but that can't be the right term ] overhead just forward of the hatch where teh bulkhead is for the head. I am not sure what kind of wood was used originally, and I have enough white oak to replace them with, but it seems like a rather extravegant use of wood. Considering the ribs are white oak, does it make sense that a load bearing 'beam' in the forepeak would be the same? Could/should I use cedar? I have a big stand of the stuff on my land, so getting it isn't a problem. So how say you? Oak? or cedar in this case?

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    Default Re: Bending Oak Without Steam

    Deck beam. Oak. Not Cedar. Need strength and holding lacking with cedar.

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    Default Re: Bending Oak Without Steam

    To bend thinner stock for trim. I cover the wood with a single layer damp towel and heat by passing back and fourth(ironing) with an old steam iron until it is plyable enough to take a bend.

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    Default Re: Bending Oak Without Steam

    This thread is timely. Yesterday, I was reading an old Woodenboat article on bending wood (oak in particular is mentioned) with heat rather than steam. It's the same issue which had the second installment of building the Grey Seal. The author used a hot stovepipe, propane heat lamp, heat gun, etc. to heat the wood. I think it was issue number 129 or 130.

    Ed

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    Default Re: Bending Oak Without Steam

    Quote Originally Posted by Thad View Post
    Deck beam. Oak. Not Cedar. Need strength and holding lacking with cedar.
    Thank you Thad.

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    Default Re: Bending Oak Without Steam

    Quote Originally Posted by Ed Armstrong View Post
    This thread is timely. Yesterday, I was reading an old Woodenboat article on bending wood (oak in particular is mentioned) with heat rather than steam. It's the same issue which had the second installment of building the Grey Seal. The author used a hot stovepipe, propane heat lamp, heat gun, etc. to heat the wood. I think it was issue number 129 or 130.

    Ed
    The reason we use steam rather than direct heat is to avoid burning the wood or drying it out too much. You are right, it is the heat that does the relaxing of the fibers not the moisture, but the moisture prevents damage to the wood. Guitar and violin makers use hot pipes to bend the wood but they first soak the wood for 30 minutes before doing so. Even then, it is easy to burn the wood on tight curves.
    Last edited by tapsnap; 03-21-2009 at 08:01 AM. Reason: spelling

  31. #31

    Default Re: Bending Oak Without Steam

    Thanks everyone for the great replies,

    Will
    Brewer Chap 25 Catboat
    Oriental, NC

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    Default Re: Bending Oak Without Steam

    Tried bending some dry white oak trim (1/4 x 3/4) yesterday using a heat gun as outlined in Woodenboat 129. I was amazed. It only took about 5 minutes of gentle heating to achieve a nice fair bend.

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    Default Re: Bending Oak Without Steam

    Can we put to rest the notion that adding a household ammonia to your soak water aids in drying wood?

    Or will someone describe in a little more detail how they did it?

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    Default Re: Bending Oak Without Steam

    I found this very detailed article on bending wood there is a lot of information in it.

    Lots of info on using chemicals for bending. It appears the simple 0 pressure steam has the best success rate with significantly less failure rates. Lots of attention to controlled drying of bending stock after it's been shaped to prevent checking especially on large bending stock.


    http://www.fpl.fs.fed.us/documnts/usda/ah125.pdf

    Rufus

  35. #35

    Default Re: Bending Oak Without Steam

    This is an unempirical method I've used on a mahogany bow rubrail. Rough dimensions were about 1 3/8" by 3" on an old Pacemaker. Hot summer day, no steam box and had to get the rail in. I laid out a length of black plastic, splashed some water in it and wrapped the rail up. I left it for about 4 hours during the hottest part of the day and it bent in with no problem at all. So, it doesn't answer the oak question and it needed the sun. I don't know how quickly you want to do this and winter sun might not be sufficient.

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