spine

[shepdogwv]

I was just wondering how exactally you find the right about of spine for your bow? I'm shooting a Bowtech Extreme VFT at about 55 lbs with GoldTip Arrows at the moment. Is there some sort of calculator that you can figure the proper spine out with? Thanks

[Straightarrow]

The best way is to bare shaft tune your arrows. Bow charts can get you in the ballpark - sometimes. To get the spine exact, may require experimenting with different tip weights, draw weights, or even arrow shaft lengths. If you want to shoot a particular draw weight, and/or tip weight, it's always best to start with long arrows and then test one, by cutting it down a bit at a time, until you hit the right spine.

[BGfisher]

One of the more useful websites is www.bowjackson.com. This site has an interactive calculator for many of the more popular arrows.

Then there is always the charts from each of the arrow manufacturers themselves, on their respective websites.
Some of the arrows are marked according to the weight they are to be shot at, assuming an average of about 29". Example might be Gold Tip 3555, 5575, 7595. One thing about most carbon arrows is that if you are on the very upper end of their spine range it's often better to go to the next stiffer arrow. Carbons work better this way.

Easton/Beman is the only company that puts the spine deflection on their arrows. The bigger the number, the more the deflection, thus a more limber spine; eg. .500, .400, .340, .300 with 300 being stiffest. Frankly they are the only ones that do it right IMO.

Carbon express does it backwards, as do some of the other manufacturers. I guess they like to cloud the issue, making us feel like a bunch of dumb asses.

[BobCo19-65]

In order to get the exact spine correct for any individual bow, you will have to do some experimenting. Personally, I set the bow at exact centershot. Then I get the nock adjusment set. If I'm tuning a compound, I'll usually set the poundage in the middle so I can have an adjustment eight way. (ex, if I have a 60-70 pound bow, I'll set it at 65). I don't buy into the theory that a bow has to be at the top end of the poundage setting. Next, I'll get the left/right adjustment set (which has more to do with proper spine). If I need to, I will change the tip weight (keeping an FOC at 9% or better), change the weight of the bow, or change the length of the arrows, before I adjust the rest away from center shot. If all that fails, and I have to move the center shot, I will not go past about 1/16" of an inch either way. If I do, I look for a different spined arrow.