Primitive Archer
Main Discussion Area => Bows => Topic started by: lleroy on May 08, 2019, 02:44:41 am
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I have a few questions about bending a stave with steam for straightening.
how long do you need to steam before bending?
does it help to let the stave soak (for a day) in (cold) water before steaming?
how much do you have to "over-bend" to get a straight stave after bending and cooling?
is it best to bend after drying or while still green?
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Give it plenty of time 45 mins minimum, but it depends on thickness.
I've never pre-soaked a stave.
Over bend by about 30%, if you find it's too much, a little gentle heat from a hat air gun will allow it to relax back. BUT wait for a couple of days first as it may relax back over time.
Dunno about green, IMO best to bend when it's been roughed out close to final size as there is less wood.
Best to bend while it is still in the steam.. e.g get it jigged up and a small steam chest built around it, I us plastic bottles, drain pipe etc . IMO it's much better than trying to pull it out of the steam and get it clamped up before it cools.
https://bowyersdiary.blogspot.com/2015/07/steaming-ahead.html (https://bowyersdiary.blogspot.com/2015/07/steaming-ahead.html)
Del
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The generally accepted time frame is one hour per inch of thickness. When I steam them, they're usually about 3/4" thick near the dips and 5/8" at the tips for a flatbow, but I still leave them in there for an hour... or an hour and fifteen minutes if I have serious corrections to make.
No, don't soak them. It's nice to do them not long off the stump while they still have a good amount of moisture in them, but I've never soaked one and never had an issue.
How far they will spring back after releasing the clamps depends on several things... the kind of wood, the degree of correction, how hot and pliable the stave was when the correction was made, how long it's left clamped to the caul, how much moisture is/was in the stave, stave dimensions, etc. But generally I over-correct about 10%.
I steam them in a 4" stove pipe, then remove them and work on them with the caul held in the bench vise where I can work all around them efficiently and effectively. On crazy osage staves, I've used over a dozen pipe clamps and c-clamps on them to correct twists, humps, whoopdy-doos, and limb alignment... all before it cools. Cut yourself a bunch of 1/2" plywood pads to put between the clamps and the stave so you don't dent the wood. Have a plan, everything needed within arm's reach, and work efficiently. There's no way I could pull some of those jobs off inside a box like Del mentioned. I've had clamps sticking out all four sides. The box would have to be bigger than a coffin. ;)
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I do the steaming in a bag which comes from an endless roll. Doing so you can clamp all the corrections while steaming. No hurrying nedded. Works really well also for whole limbs. cheers
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I agree with Del's assessment. I haven't used steam much but that is how I'd do it if I were to steam again.
Simk's set up works well. I watch Clint use a similar set up last year at the Classic. It worked very well.
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Like everyone said. Bread bags and the like work well but remember to use them right side out. The paint/dye they use will stick to the wood.