Primitive Archer
Main Discussion Area => Arrows => Topic started by: DC on December 05, 2017, 12:25:21 pm
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Does anyone have a link to a place that will tell me the nuances of spining. I'm looking for stuff that tells me if I change the tip weight by 25 grains the spine changes by 5#, stuff like that. I searched and I can't find one. I will bookmark it this time.
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http://heilakka.com/stumiller/
has a spreadsheet that lets you make adjustments and see differences in dynamic spine
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That seems to be for aluminum arrows, did I miss something?
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if you click on box 1 where it says 2016, there appears a small arrow in the corner of box two.
when you click on that box there is a dropdown of all the carbon and alu arrows, but at the bottom is 'Wood"
you select that and the manually enter your wood data in C6, C7, and C8
I am not using microsoft excel, so your sheet might not be exactly the same
with the bow, pick the nearest generic, and manually enter your centershot in G13
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It won't open. It appears I don't have Excel or equiv. on my computer. So that's out.
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DC, for commercially spined shafting, the spine values are for a finished arrow, 28" long arrow(from crotch of nock to before point) with a 125gr point. For each inch over 28" subtract 5# of spine weight(opposite for shorter) and for each 25grs over 125grs of the point subtract 5# of spine weight(opposite for under 125grs). This will give you an effective spine value.
This works for commercial shafting, cane and hardwood shoots. Another factor with cane and hardwood shoots, you can subtract almost 10# of spine weight for the natural taper. Some cane tapers more than others so that should be considered too.
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Thanks Pat. Don't know why I can't remember that. Old I guess. A little clarification on the tapered shaft. Subtract 10#. Does that mean with tapered shaft the spine should/can be 10# less than a parallel shaft?
Isn't there a rule for string offset? 5# for every 1/8" or something?
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no spreadsheet on your computer for real? what os you have? I had to get it out of read only mode before it would do anything
heilakka.com/stumiller/Dynamic%20Spine%20Calculator%20Rev%2012-25-10.xls
is the actual download, there were mismarked links on that page also
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DC, I don't know about the string alignment but I can see how bit matters, kind of like center shot or not.
Yes, the spine can be 10# less but I think it depends on the degree of taper.
I learned this from Art Butner(artcher1) years ago while I was learning to make cane and hardwood shoot arrows. I make my arrows 30" for my 26" draw so I would figure out that value plus subtract 10# for the taper when making these types of arrows. I generally shoot 125gr points but sometimes I'd use stone which seemed to be lighter in weight. I also think the weight forward of these naturally tapered shafts helps with the arrow flight.
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You loose 5# of spine Dynamically for every inch you add to the arrow over 28" and every 25grain increase on the point. I personally do not like the added length as it adds mass to arrows I have already at 550 grains. Added weight add Kinetic Energy, but reduces cast, or make the arrow drop faster.
I am shooting a non-center shot primitive D bow I shoot 42# spined arrows on a 55# bow. That is what bare shaft testing told me I needed.
I wrote it many years back, maybe it answers some of those question, but a rule on non-centershot to spine reduction rule I do not know about. It needs to be reduced in spine, but there is not a hard rule except bare shaft testing.
boweyrsden.wordpress.com/2014/02/18/5-shaft-reduction-and-spine-qualities/ (http://boweyrsden.wordpress.com/2014/02/18/5-shaft-reduction-and-spine-qualities/)
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I recall that 3Rivers has Stu Miller's dynamic spine calculator on their website.