Spine

[bow101]

This subject probably come up before.  How do you get different spine for same diamater, lenght arrow shaft.
Thinking of making my own, but    blank on this spine issue.

[Olanigw (Pekane)]

How does it happen?  Density and flexibility of the wood differs with every shaft, even if they're from the same board.

[bow101]

How does it happen?  Density and flexibility of the wood differs with every shaft, even if they're from the same board.

Makes sense, but a spine difference of say 30..?

[twisted hickory]

I have had red osier from the same bush be much different in spine. For example two 540 grain arrows shoots fine out of a 50 lb bow one seems a little stiff. Shoot the same arrows out of my 65 lb bow and one is fine the other is dangerously under spined. BTW a 65 lb bow will destroy red osier arrows shot into the dirt. It is intresting. I don't have a spine checker cause I have found that if the arrows are similiar in weight they fly good for the most part. You get the odd ball arrow now and then. I do have plans to make a spine checker this summer to dial in the arrow spine and see what happends to accuracy. Right now my shoot arrows do good to 25 yards.
Greg

[Slackbunny]

Are you making sure that you are measuring the side of the arrow with the weakest spine? Spine will change a bit as you rotate the arrow.

So maybe you have measured the strong side of a stronger shaft, and the weak side of a weaker shaft resulting a in a higher than normal variance.

That's just my theory.

[BowEd]

It takes experimentation and time bow101.Get yourself a spine tester.You can barrel shape reduce weaker ones to match stronger spined ones or make the stronger spined ones longer to match the weaker spined ones.Once you get to understand what's going on you can dial them in.My better arrows usually have a spine weight within 5 to 10 pounds of each as I rotate them on the spine tester.The stiffness of your string and setback of your tips and poundage of your bow all contribute to what spine weight you want on your arrow shafts.Along with whether your bow is center shot or not too.