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Strip bamboo arrows
willie:
--- Quote from: DC on September 26, 2020, 04:05:17 pm ---That's something I never thought of. What direction would you put the grain. Maybe with the growth rings radiating out from the center? If you had primo glue joints that would confuse the troops, edge grain all the way around the arrow ::) ::)
--- End quote ---
I think so. when you spine a shaft, it is often recommended to put the rings lines up and down, thus you are finding the spine in the stiffest direction. when placing the nock. it's often recommended to orient such that the stiffest direction is against the riser/site window. I think this advice presumes the arrow flexing the most side to side on release on account of the nock flipping off the fingers. and the less stiff side of the arrow hopefully does not come into play.
in a situation like flight shooting, reducing stiffness of the arrow to its practical minimum is done when reducing diameter for aerodynamic advantage, so arrows with less stiff sides might be a disadvantage.
if you placed the stiffer/denser part of the wood growth ring flat on the outer most diameter of an arrow in an annular fashion (with a correspondingly lighter pith towards the center) the physics would be on your side, but you would have to find a board with straight grain ring line for a parallel shaft, or a gentle curving ring line that matched the barrelling desired for a barrelled shaft, and saw each section to follow the early/late ring line.
it could be done, but bamboo might be easier
DC:
--- Quote from: willie on September 26, 2020, 04:48:14 pm ---
--- Quote from: DC on September 26, 2020, 04:05:17 pm ---That's something I never thought of. What direction would you put the grain. Maybe with the growth rings radiating out from the center? If you had primo glue joints that would confuse the troops, edge grain all the way around the arrow ::) ::)
--- End quote ---
I think so. when you spine a shaft, it is often recommended to put the rings lines up and down, thus you are finding the spine in the stiffest direction. when placing the nock. it's often recommended to orient such that the stiffest direction is against the riser/site window. I think this advice presumes the arrow flexing the most side to side on release on account of the nock flipping off the fingers. and the less stiff side of the arrow hopefully does not come into play.
--- End quote ---
I've wondered about this. This is a hard situation to describe and I've read arguments where people were adamant that they were right and the other guy was wrong and it was just their description of what was happening that differed. They were both saying the same thing. I'm going to try ;D I think that the arrow should want to bend away from the bow on release. This can be due to three things. The finger effect that you mentioned but my gut says this is backward. I'll have to look through Tuomos videos to see if I can convince myself. Next is spine oriented so that the arrow wants to bend away from the bow. I'm not even going to try and describe which way the stiff side is facing. And third is one that I've never heard discussed is any slight bend that may be in the arrow. If the arrow is bent that will direct which way the arrow bends, above all else, I think. A good test for arrows would be to have a jig that compresses them lengthwise. See which way they bend from that. Position your cock feather accordingly.
willie:
--- Quote ---And third is one that I've never heard discussed is any slight bend that may be in the arrow.
--- End quote ---
this is called eccentric compression. definitely a factor in engineering calcs. of course all archers shoot straight arrows, no?
--- Quote --- I think that the arrow should want to bend away from the bow on release
--- End quote ---
if you flip the nock end away from the bow with a Mediterranean release, the arrow center is bent towards the bow at the moment the string applies the load? I think the trick is to have the arrow be flexing away from the handle a half cycle later as it clears the bow. shooting off the thumb changes things of course.
--- Quote ---spine oriented so that the arrow wants to bend away from the bow.
--- End quote ---
my guess is with a straight arrow and a mechanical release that imparts little lateral force on the nock at release, spine orientation would become more of a factor. Wouldn't a stiffer arrow vibrate faster, but with less deflection (amplitude)? Maybe Tuomo has some slo-mo of flight arrows somewhere?
--- Quote ---A good test for arrows would be to have a jig that compresses them lengthwise. See which way they bend from that.
--- End quote ---
this is actually a preferred way to spine atlatl darts by many. I have duplicated a native dart of elliptical cross-section. (it was designed to be thrown flatter sides up and down). the dart, like many others, has a somewhat heavy head that makes the dart droop when held in throwing position. my conclusion is that the dart was tuned to the proper spine with respect to a single side, and just about had to flex in the desired direction with any reasonable throw.
DC:
--- Quote from: willie on September 26, 2020, 07:04:51 pm ---if you flip the nock end away from the bow with a Mediterranean release, the arrow center is bent towards the bow at the moment the string applies the load? I think the trick is to have the arrow be flexing away from the handle a half cycle later as it clears the bow. shooting off the thumb changes things of course.
--- End quote ---
So the initial flip is in the "wrong" direction and you're depending on the timing of the oscillations for the arrow to clear the bow? What determines the timing? Arrow length? Spine?
bownarra:
With wood shafts it is going to make next to no difference regardless which way you orientate the grain. On a normal shaft you might get one unit of difference.
divide that difference by 6....:)
I don't think there is any worthwhile gain to go with sectional wood arrows.
The sectional cane arrows are worthwhile because you are using the stiffest part of the bamboo AND they are hollow :)
I'd recommenr making some and see the difference compared to equivalent wood shaft.
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