Primitive Archer
Main Discussion Area => Bows => Topic started by: tattoo dave on January 03, 2011, 09:22:42 pm
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Hi everybody, I hope the holidays were good to all. I'm just sittin here thinkin, what wood has the strongest compression strength? I'd like to make a short bow, 40-45" range, but would like to experiment with how narrow and thin I could get it, and still be in the 45-50# range. Does sinew, flax, or any other kind of natural material help with compression strength. Thanks for the input.
Tattoo Dave
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Osage I think has the highest. Sinew would help with tension strength (back). Jawge
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Sounds like you are wanting a horn bow.
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I'm sure some others will correct me if I am wrong, but if you are wanting narrow and thin, then tension strength will be your limiting factor, rather than compression strength. Sinew and flax won't help with compression, although if you use a strong compression wood with weak tension strength, you can make it narrower with a backing such as those. I have read that horn is great in compression, but is super labor intensive. You might try talking to Ed Scott about that if you can.
For your first question, I dunno what has the highest compression strength. Osage likely. Maybe ERC or some other juniper?
Sounds like a fun project. Enjoy!
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Thanks for the input. Yes horn would be the best, but horn is not in the budget at the moment, and i've never worked with it. So, I wanted to experiment with all wood, just for fun. ;)
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O'sage,no sinew won't help.
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Ipe is the wood for a short powerful bow like this.
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It is not likely to be Osage. Osage does have high compression strength but what it is more known for is it's elasticity. Ipe has very high compression strength but I think that African Blackwood has one of the highest compression strengths along with Lignumvitae. Now understand that high compression strength does not necessarily mean a wood will make a good bow. Wood also needs to be elastic and it is a very elastic wood that will make a great bow
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I read somewhere that black locust has the highest compression strength. But that is straight down compression strength, not bending compression strength. It was used for grinding stone bearings I think. It is brittle and doesn't have the elasticity which makes it susceptable to fretting.
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I've made quite a few hickory backed ipe D bows. I think it would be a good thing to fiddle with. I bet you could do a 52-55 inch D bow and D cross-section, very narrow tips for a slightly shorter draw, I dunno 24-25 inches at that weight that could be very efficient at an inch of width, probably less...
Just use a piece of ipe that looks free of any defects in the grain.
I've been thinking of making a shorter one like this for a short draw with arrows maybe at 27" or so.
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Im with Marc on this one...compression strenght alone wont help you much. Drawlenght and stack will be serious limiting factors too. If you want a backed wooden bow (horn might fit your needs better) then considder elastic wood like Yew and Juniper (sinew backed)...but dont expect drawlenght much longer than 22-24"
Cheers
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It sounds like I need some Ipe. I'm thinking something laminated, as opposed to a self bow, so a thin layer of ipe on the belly side might help with compression, and maybe some osage for the backing. I"ll give it a go and see what happens. I 'll post some pics at some point, whether it blows up or shoots, i"ll let you all know. Thanks again.
Tattoo Dave
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A narrow self bow will put a lot of strain on the wood: in compression, shear, and tension. Ipe would be best, IMO. Make the belly more narrow than the back.
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Osage will make the narrow bows because it has one of the highest densities of the domestic woods. Osage has a very high elasticity too. Suggested reading is TBB 1...Tim Baker's chapter on design. Jawge