Primitive Archer
Main Discussion Area => Bows => Topic started by: sieddy on January 26, 2015, 05:28:52 pm
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Hi fellas Any thoughts on the above topic? All input as always greatly appreciated! :D
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Red oak isn't strong enough for a boo backing. IMO I'm sure it can be done but I wouldn't suggest it.
Bamboo is very strong in tension so a wood that is strong in compression would be a better option for the belly.
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Thanks Pat I kinda thought that would be the case.
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You could probably do it if you made the bamboo very thin
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Thanks Lee it might be worth having a go then. Only thing I don't have access to a belt sander so I might struggle to make it thin enough! ::)
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My limited experience with bamboo thought me that thin is an understatment.
1/8" thick is the thickest use can get it for ipe belly! If I where you, I`d use the red oak to make a self bow.
If the grain is so-so- back it with brown paper, silk or linen. Flettening bamboo takes some time (especialy without a belt sander)
and it will suck to have the bow chrysal like crazy.... Save the bamboo for a stronger wook like ipe, osage or yew heartwood.
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You can find a beautiful example of a successful bamboo backed red oak bow HERE (http://www.primitivearcher.com/smf/index.php/topic,23267.0.html). The key is to not only keep the bamboo very thin, but also to make it narrower than the belly. While it is possible, I would advice a more gentle wooden backing such as maple or ash for red oak. But if the grain is good, a selfbow is of course the easiest for red oak.
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Top tips as always guys. With my level of craftsmanship I will definitely err on the simple side (which as I learnt from a famous member of this community- is not easy!) ;)
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Don`t mean to hijack the thread, but how about boo backed white oak?
I have 2 WO boards with pretty iffy grain that I want to splice and back with boo.
Any suggestions for dimensions?
Dor
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You could probably do it if you made the bamboo very thin
Tim Baker argues that rather than thinning (which I WOULD do) narrowing is even more important, so trapezoidal limbs are in order. Almost all the tension/compression forces are felt in the first 10% of limb thickness, both back and front, the back barely stretches at all, and the belly must take the load. Dauntless's bow that Darksoul posted a link to is a perfect example of how to pull it off. Notice it is wide where it bends, trapped, and reasonably long.
NOW, that said, BACKED bows fail in compression for the same reasons SELF bows do. Elm is great in tension, and mediocre in compression, and there are a LOT of wonderful elm bows out there. Now, boo is even better than elm in tension, and oak is (in my experience) worse than elm in compression, BUT if the boo was thin and trapped, and the oak was wide and dense, you could make it work. Red oak varies a LOT in density. I had a flat sawn craft board once where the entire 1/2" thickness was ONE growth ring and a little bit on the edges. SG was like 0.74; very heavy for oak.
Another consideration (not to get too fancy) is the use of the Perry reflex to relieve some of the belly compression strain on the oak. If you went R/D by using steam to deflex the handle area, then pulled it back to reflex, that mioght help. Gotta warn you, though tillering a R/D bow is weird.
So, there's about all i know about it. And all that said, I still think you'll be ebtter off backing stiffer wood with bamboo; at least as hard as black locust, say. Or much more elastic wood, like yew or juniper.
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Don`t mean to hijack the thread, but how about boo backed white oak?
I have 2 WO boards with pretty iffy grain that I want to splice and back with boo.
Any suggestions for dimensions?
Dor
Density is pretty close to red oak for most varieties commercially available. All my experience with white oak is using it as backing, but I hear it benefits more from heat treating than red oaks.