Primitive Archer
Main Discussion Area => Bows => Topic started by: vinemaplebows on March 13, 2012, 09:50:23 pm
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I have wondered about this for quite a while...If you cut a stave decrown it would the wood closer to the cambium layer be a better belly than the heartwood??? Otherwise, turn the stave backwards?? If wood nearer the center of a tree becomes more brittle (in theory) then would the sapwood be able to outpreform the heartwood? This reference would be more tward whitewoods.
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I remember reading in TBB vol 1 (I think) about reverse sapling bows. Seemed to work ok.
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If wood nearer the center of a tree becomes more brittle (in theory)...
Where did you find that? I think that's a misconception: wood doesn't get more brittle towards the center of the tree. It becomes harder, often with higher compression strength and possibly more elasticity. But it does depend on the species. Sapwood is (at least in hardwood) usually weaker in compression than heartwood. This favors the use of heartwood for a belly over the use of sapwood.
Reverse saplings do exist though, as Bevan points out. But that would work best for species with sapwood and heartwood with about equal strength properties.
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I have done this with a small diameter Osage branch. The first few rings were so tiny that I chased a ring from the center of the branch or the split and tillered off the sapwood side. Worked ok as far as I could tell. Mind you that it was not a real high poundage bow though. Around 40# if I remember right.
I should also add that I put some rawhide on the back as well.
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Gary and I built a couple like that with Osage,worked great. Note the bark still on the handle of mine. :) This was a small diameter tree split down the middle. :)
Pappy
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I heard many years ago that Hickory heartwood was more brittle than the sapwood and I believe that Black Cherry sapwood is more elastic than the heartwood. On the other hand I have made some bows out of Elm heartwood and it worked quite well.
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Thanks for yur thoughts. :)
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While I'm sure this can work, I'd say think about the tree first. Tree's put sapwood on the outside. Its the part of the sapling that has to bend the most when the wind blows. Sapwood on a tree does pretty much the same work that sapwood on a bow does, it resists tension, and absorbs more motion, but relies on the heartwood to maintain bring it back to form (e.g. to resist compression).
Just an uneducated observation, but I don't see much reason to do it backwards from the way nature grew it. But somebody will definitly prove me wrong by showing the benifits. ;D ;D
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I think the reason and or benefit of doing this is to use a piece of wood that might otherwise not be useable. I like to make something from something if that makes sense ???
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Generally you decrown the back and round the belly if the wood is weak in tension/strong in compression. A split sapling would be a quick route to that end. The back would be no different from a quarter sawn board and the thickness taper would be mostly done for you on the uphill end of the bow. I might have to try that if I find a straight little cherry in my travels, or maybe an ERC.