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Main Boards => The Bowyer's Bench => Topic started by: Bryan Adolphe on June 15, 2024, 12:16:00 PM
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Question for you all with the same thickness of core laminations will rock maple finish heavier than bamboo ? Or will they be close to the same. Thanks for your input. Cheers have a great day. B
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The best combo i have found is bamboo back, and maple on the belly side. The bamboo has higher tensile strength in tension, and the maple has better compression properties. You can get away with 100% bamboo cores in long bow limbs and get a wee bit better performance, but with hybrids, and recurves with shorter working sections, the maple up against that belly glass is hard to beat.
btw... both of these woods have great longevity, and they have been building 100% maple core bows for over 50 years that are still going.....But the bamboo adds to the performance.
With that being said... All bamboo is not created equally. There is a Hell of a difference between high grade carbonized, heat treated, moso bamboo, and natural bamboo of unknown species and origin... HUGE difference....... Kirk
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My swap bow was built all bamboo through and through with all the data points being identical to a preliminary build that was all maple. The difference was. . . . . Nil. No difference.
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:thumbsup: Thank you Mike :archer2:
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Same here Longcruise, what does make a difference is the way a limb bends and the shape.
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If one spends the time to study the math behind the 'composite beam' that is a bow limb it is evident that the wood core provides roughly 8-9 percent of the stiffness of the limb in a wood/glass bow. In my carbon limb designs the math reveals it is about 5 percent. There will be a slight difference in the core's contribution to the stiffness depending on the wood due to its modulas of elasticity. Maple has a higher modulus by almost two times.
I once modeled a 50lb. glass limb with maple core and then changed the core material to several different woods. The bamboo limb came in at 47 pounds. Mind you, I did not build these limbs, just calculated them based on material properties. With a carbon limb the difference is negligable.
I use nothing but maple for my cores.
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On some test bows I found maple to make 2# heavier than actionboo and red elm same as aboo. Walnut about 3# lighter than boo.
These were black glass with all cores of above woods.
Some folks swear the aboo is smoother ,but I must be an insensitive cuss, I can't.
EDIT -- the aboo is pretty consistent in weight produced, whereas the lumber milled into lams may vary tree to tree and even board to board from same tree...
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Cupcake I might be wrong but I think bamboo has a higher MOE than hard maple and also had a higher specific gravity- but, like Kirk said maple is much better in compression while bamboo shines over maple in tensile strength- in my hill builds I see a negligible increase in weight with maple vs bamboo.