Primitive Archer
Main Discussion Area => Bows => Topic started by: jeffp51 on December 29, 2014, 12:59:10 pm
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What is the current thinking on decrowning a stave? I have been rereading TBB-I where the topic is discussed at length, but I seem to remember something here that contradicts the idea. I have a mountain maple stave that is pretty well crowned. It has other issues as well, and is going to be a challenging piece.
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Don't decrown. Most wood is 3 to 4 times stronger in tension than in compression, so if only a third of the back is doing the work, all is well.
Yew, cherry and red cedar are exceptions to this rule.
I have made bows from 1-1/2" diameter saplings and the ones that failed chrysalled on the belly.
Jim Davis
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If decrowning didn't "work" it would be impossible to make a bow out of a board stave. The back of a decrowned sapling is essentially a plain sawn board, rifts, and quartersawn all in the same thing. BUT,
Tension strong woods from small diameter trees (vine maple, other hard maples, white mulberry, plum, hickory, serviceberry, elm, etc, ) tolerate the tension on the crown very well. And if you make the bow as wide as that small sapling will tolerate, with a flat belly, you'll be ok.
Decrowning takes a lot of skill, too, so if you already have waves and knots, leave it intact and work around the grain.
OCCASIONALLY i have had red elm with very tiny thin growth rings pop up paper thin slivers on a crowned bow, sometimes in several spots. That is literally the sum total of my problems working with crowned wood.
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I have never decrowned a stave and don't see a reason to do so. Make the belly side flat and you should be OK.
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beautiful. That is one less thing I will have to worry about.
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A knot or flaw in the natural back is a good place to lift a splinter. Depending on the amount of crown, the amount of flaw, and the amount of flex, I'll decrown so I can back it with rawhide or sinew. Also decrowning can be used to regulate the amount of tension to compression wood--i.e. a high crown can be brought down to something reasonable.
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Decrowning is best done on bows 68" or longer. Just my opinion. No matter how skilled you are, decrowning is a pain. I've made two and they work but they were not worth the trouble. Making a reproduction of a decrowned Native American style bow is probably the best and only reason for decrowning.
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Decrowning is best done on bows 68" or longer. Just my opinion. No matter how skilled you are, decrowning is a pain. I've made two and they work but they were not worth the trouble. Making a reproduction of a decrowned Native American style bow is probably the best and only reason for decrowning.
Not if you have a jointer, and I decrown lots of woods, Yew, Cascara, to name a few.
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Doing a decrown is not as simple as it sounds. The dips and humps have to be followed so that those longitudinal fibers are not violated.
It is not a board stave for that reason.
I do not believe a jointer/planer would do a decrown properly but it may turn the stave into a board.
I don't decrown but have a time or 2. I just leave the stave a few inches longer to counteract the crown.
Jawge
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Yes, you are right George, I had lumber in mind, not decrowning.