arrow spine question

[snow leopard]

say i have a 28" arrow spined #40-45. if i cut it back to 26"bop, how much has the spine increased? thanks.

[rraming]

Static or Dynamic? - the arrow stays the same - who you foolin'

[snow leopard]

my understanding was that if an arrow is spined at a particular length, said spine increases as you decrease the length of the arrow. the spine gets stiffer. this is what i'm trying to find out.

[Hud]

My spine test is set for 26" O.C. and calibrated to give spine for a 28" arrow. If you take an inch off the arrow, you could expect to shoot it out of a bow about 5 lbs heavier at 27". A 26" should shoot out of one 10 lbs heavier at 26". I think you can get a spine chart online at 3Rivers. It is for Aluminum/carbon and wood with recurves or longbows. Don't forget to allow for weight up front.

http://www.3riversarchery.com/pdf/ArrowCharts.pdf

[snow leopard]

thank you for the link. i just printed a couple copies of the chart. also forgot to mention my question was with regard to wood arrows.

[Grey Taylor]

In a manner of speaking, rraming is correct. Shortening the shaft does not change how it will read on a spine tester, that's the static spine.
Shortening, or lengthening, the shaft will change the dynamic spine, the way it shoots out of a bow.
If I remember right, 1" of length equals about 5# of dynamic spine. That's for a shaft longer or shorter than 28".
Shorter shaft = higher dynamic spine.
Longer shaft = lower dynamic spine.

Clear as mud, right?

Guy

[snow leopard]

thanks, guy. that's what i was looking for; the #5 per inch. i thought that's what it was, but wasn't sure. memory------.