Kevin, just experiment for yourself. Do a search on line and you will find it. Stu's calculator has most people I know who have used it, myself included over spined by at least 15#s ecsp. when recommending carbon. Shawn
The comments about spine issues is with carbon. I have yet to see any issues raised with aluminum or wood. If I went 20# under spine with aluminum, I would have a wet noodle for an arrow. I think the calculator is on when only looking at spine deflection number as they relate to other materials. However, from what I have seen, carbon reacts so fast it can have issues clearing the bow, and will not plane of line as much as other materials. So I believe the dynamic spine of carbon is different than the measured deflection spine.
-------------------- Firefly Long Bow James 4:14 60" MOAB 54@29 James 1:17 Michigan Longbow Association Posts: 3624 | From: Kalamazoo, MI | Registered: Jan 2009
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Have found Stu's calc to be a valueable tool for getting you in the ball park and for keeping track of my final set-ups.
My final set-ups typically end up from ten to 30 pounds below the recommended spines. The extreme upper range FOC's may even call for more than 30 pounds. These findings have been observed when achieving final tuning of my shafts tipped with a large dia. 3 BL BH; shot from both 3 yards and 25 yards. Actual observations utilizing BH's is always my final verification.
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My Lands… Are Where My Dead Lie Buried.......Crazy Horse Posts: 3976 | From: Hanson, KY | Registered: Apr 2008
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Most folks just do not measure and weigh as precisely as this tool requires........remember "garbage in equals garbage out"?
The easiest way to find your calc output throwing a number at you that ends up overspined is to put your "best guess" in for center cut.
The next time you have the calc open, play with some of the input numbers....by + or - 5 or 10%.....and see what it does to your dynamic spine output. Bottom line....weigh and measure everything.....twice!
-------------------- TGMM Family of the Bow Compton Traditional Bowhunters
“Only after the last tree has been cut down…the last river has been poisoned…the last fish caught, only then will you find that money cannot be eaten." - Cree Indian Prophesy Posts: 1853 | From: Westchester County, NY | Registered: Oct 2006
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Agree that it is mostly carbons that the calculator has people overspined with, by alot! I mean 20-30#s overspined but a bit overspined on other materials too. xtrema312 is correct about carbons and their ability to recover from paradox. Shawn
I may be wrong here. I just reread the instructions for use. It says spine must be entered at amo or 26" centers. It gives .825 to divide by to get this. The carbon I've been shooting is under by 15 lbs.But, when I do the conversion using the instructions it is perfect! The spine of my carbon goes from 92.7 to 112.36 using the conversion instructions. Is this right or wrong?