Primitive Archer
Main Discussion Area => Arrows => Topic started by: Accipiter on August 16, 2018, 08:40:32 am
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Has anyone ever noticed large discrepancies between the measured draw of their bow and the dynamic spine of the arrows that shoot best out of it? I measured the draw weight of my new bow the other day, and was a little disappointed to see it coming in at the low end for hunting (43# @26").
Realizing that my current arrow set was a good bit stiff for that, I used Stu's spine calculator to figure out the proper dynamic spine, which was about 38#, and then make some bareshaft arrows to that spec. But, when I shot them from 10 yards, they were nock wayyyy left. So much so that I broke two in quick succession, just from impact stress! One of those arrows where the tip had snapped off I superglued another field point on, and shot the new arrow (which was about 3.5" shorter and 15# heavier) at the bale, and it stuck in just a bit nock right. Then this morning I made another bareshaft with 48# dynamic spine, and it shot in just about perfect, just a hair weak, which should correct once I fletch it.
So, according to the spine calculator, my bow draw weight would need to be in the mid 50's to shoot that arrow straight, which seems possible but not likely. Do some bows just prefer stiffer arrows, or did I measure my draw weight wrong? Or is there some other possibility I'm missing? I think this is a reasonably fast bow bow for the weight, but I have a short draw and I'm no master bowyer, so I don't think its any marvel of efficiency ::) Thanks!
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The spine calculators are just a rough estimate. For me, they have never worked. I'm not sure what it is, but most of my bows need the same spine as bow draw weight or more. Done worry about the numbers, shoot the spine that the bow shoots well
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I think that it's how fast the bow is that determines the spine. It's acceleration that bends the arrow and a faster bow has to accelerate the arrow quicker. If you have two bows both 40 # and one shoots 150fps and the other 180fps the 180 one will want a stiffer arrow.
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a lot of things come into play with correct arrow spine.
the calculaters only get ya close.
I have a little longer draw so I tend to shoot a stiffer spine on most bows,
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Woods bows will forever fool the charts because they are rarely the same twice. I just start stiff and work my way down in spine. I grab several known arrows out of the racks to do that rather than start with one extra long arrow and cut it down to tune.
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Ok, this is all good advice to have in my head, thank you! And, I guess I'm happy that my bow is at least not shooting slower than estimated for 43#. Now I just gotta get my knocking point figured out!
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Is it possible you inputted a bad datum? Such as the centershot measurement? At least you found the right spine!
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Oh, its absolutely possible! I dont have a great setup for measuring the centershot, but I think I'm within about 1/16"...I think. And yes, it was pretty darn nice to see the bare shaft sticking in nice and straight.