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Main Boards => PowWow => Topic started by: TomBow on July 12, 2012, 02:10:00 PM
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I am gathering information for my database on arrow weights for wood arrow shafts. If you have numbers for different shaft materials and corresponding grains per inch for certain spines please respond.
Example: my first (and only, so far) set of POC arrows, 60-65 gr. have a gpi of 13.125 grains.
I am putting this together so I can have a quick reference when I start calculating what a certain arrow layup might end up weighing. I am toying with the EFOC numbers and doing calculations and numbers are easy to find for carbons but it is hard to find gpi's for wood. Any help would be greatly appreciated. THANK YOU my brudders!
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The latest set of wood shafts I bought were Douglas Fir, 45-50#, and weighed 10.86 gpi.
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Your dealing with a natural product. (wood) Even your poc the weight will vary shaft to shaft. When buying wood it is best to buy in quantity and then spine, weigh and bunch accordingly in order to get your tightest grouping. Even then it is a bit difficult to get anywhere near the consistency of carbon shafting.
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At a given spine and shaft diameter, many woods will vary as much as 100 grains or more. Shafts will vary as much as 3 gpi or more within a single species of wood, and 5-8 gpi or more between different species of wood, at the same diameter and spine.
If you manage to collect a lot of numbers, you'll end up with a range of gpi for a given wood, spine, diameter. However, that range will be quite large (compared to carbon or aluminum), and of questionable value in designing/creating wood arrows IMO.
But good luck in your endeavor.
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Wood can vary so much,I have 70-74# POC that weigh usally around 550 to 570.And had another set of 70-74# POC that weighed 670 to 685.Both were 23/64" tapered shafts POC,a pretty big difference.With wood I never really worried about weight,they were ually heavy enough for which bow I was shooting.I worried more about spine consistency from shaft to shaft.
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This information confirms my suspicions and echoes what others have stated: Too much variance in gpi to nail down "this wood, at this spine equals this gpi" because of the wood being a natural product. So much easier to use synthetic materials which come with detailed and primarily "fixed" numbers. Still, my satisfaction with the flight of my first and recent set of POC arrows has been the best to date. Primarily due to my previous carbon shafts coming up a bit over-spined and their less forgiving nature. My Chapter on wood continues. Thanks again.
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I order the same wt. ranges when I order shafts. No more variance than the cheaper carbons such as gold tip. That is unless thay has improved over the years. On that note I find Doug Fir tougher, safer and more duradle than Carbon.
(This information confirms my suspicions and echoes what others have stated: Too much variance in gpi to nail down "this wood, at this spine equals this gpi" because of the wood being a natural product.)
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Some shaft suppliers are happy to match shaft spines and weights as close as you want. It does however take lots of time, work and shafts to do this. Within a given 5 lb spine group shafts can vary quite a bit in weight. I see 150+ grain spread with doug fir, about 100 gr with POC and only about 40-50 gr with sitka spruce.
The first time I went thru 100 fir, I ended up with 2 dozen that matched within 5 lb and 10 grains. It was a shocker. :eek:
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POC: 60-65 spine
1 set is 14.10 gpi
2nd set is 11.96 gpi
Spruce: 75-80 spine
1 set is 15 gpi
2nd set is 14.21 gpi
3rd set is 13.18 gpi
Fir: 80-85 and 75-80 spine
1 set is 21.07 gpi
2nd set is 14.28 gpi
Gotta agree with Orion though. God Bless
All are matched 10 +/- thrughout the dozen
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As many have said, there are going to be variables with wood, that is part of what makes them magic. Every shaft has it's personality. Build them, shoot them, pick the one that will be your hunting partner. Success is when the bow, the arrow and the archer meet on the other side of the target.