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AVCase design Arvin bow build
Selfbowman:
It’s sure fun to back at it!
sleek:
Hey Arvin, how wide and long is that bow?
bradsmith2010:
thank you for posting,, very nice ,, :)
simk:
Nice bows and very interesting cooperation Arvin and Avacase! A rectangular cross section might be the most efficient, as long as it matches the specific wood used. Curious about you being reverse checked Arvin :)
cheers
mmattockx:
--- Quote from: bradsmith2010 on March 08, 2023, 12:04:43 pm ---the red oak lam bow is not the same as an osage stave,,
so dont think that is a good comparison,,
--- End quote ---
I would say that wood is wood as long as you know the properties of the individual piece. As long as it is consistent along the length of the bow (which isn't always the case) it will always bend as predicted.
--- Quote from: bradsmith2010 on March 08, 2023, 12:04:43 pm ---you wont know what kind of set the bow is going to take until you shoot it,, at given draw,,
--- End quote ---
Yes. As I said, the two things that are hard to predict really accurately are draw weight and set, because they depend on properties of each individual piece of wood. As long as the wood in the bow is consistent from end to end then I can predict the bend pretty accurately. If you have a knot or soft spot then it will throw that off.
--- Quote from: bradsmith2010 on March 08, 2023, 12:04:43 pm ---drawing the bow on a tree has a different effect than somone actually shooting the bow
--- End quote ---
Yes it sure does, even if you set the bow to rock on the tree and pull exactly where the archer will.
--- Quote from: bradsmith2010 on March 08, 2023, 12:04:43 pm ---I think the bow will be very close,, im just saying it will probably have to be adjusted after it is shot in,,or the moisture content changes,,
--- End quote ---
This sounds about right. I figure the math will get you over 95% of the way home, but wood always has a few quirks that may require attention.
--- Quote from: bradsmith2010 on March 08, 2023, 12:04:43 pm ---the red oak bow looks great,,,how many times had the bow been shot when photos were taken,,
--- End quote ---
It was finished in the one picture, so it would have been shot hundreds of times by that point.
--- Quote from: Selfbowman on March 08, 2023, 03:04:18 pm ---The engineer may been using a different wood model.
--- End quote ---
To be 30% off in draw weight means the modulus of elasticity was a fair bit different than what Alan assumed it was. This is one of the challenges of doing this with wood. If I want a bow to be spot on for weight I will do a bend test sample off that specific piece of wood in order to be as close as possible. Limb thickness also plays a major role, but you would have to be off a fair amount to lose that much weight. If you were careful with removing material and measuring with calipers you should have been close enough to be in the ballpark.
--- Quote from: simk on March 09, 2023, 03:13:27 am ---A rectangular cross section might be the most efficient, as long as it matches the specific wood used.
--- End quote ---
Rectangular is absolutely the best cross section in terms of sharing the strain equally among all the wood in the limbs, but that isn't always the only consideration involved.
Mark
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