How do you determine the right spine?

[Yimmy83]

How do you determine the right spine of arrows for your set up? Is it draw length by poundage or is it arrow length by poundage? And how much of a factor is it really?

[Paul L Mohr]

Having the correct spine for your set up is probably one of the most important factors in shooting accurately, especially with a hunting set up using fixed blade broad heads.

It is comprimised of length of the shaft, tip weight, draw length, draw weight and the effeciency of your bow.

You can use charts and online calculators to get you in the ballpark but some of the newer archery software works very well. Like OnTarget2 or TAP.

This is where an experianced pro shop also comes in handy.

Paul

[waltwittman]

eastonarchery.com has the software where you can plug in all of you info and will tell you what you need and if you look and the spine tollerances you can transfer them to any manufacture.
yours truly
walty

[Straightarrow]

Since arrows vary quite a bit, the only real good way, is to test for spine by bareshaft testing. Once you do this and get your spine correct for the bareshaft, I'd recommend that you drop your draw weight by a couple pounds, because shafts (especially carbons) tend to vary enough that you will get some shooting slightly weak and others shooting slightly stiff. It's better is get them all on the slightly stiff side. A spine tester will also greatly enhance your ability to get them all shooting close to the same stiffness.