A Question On Spine

[agd68]

Ok, I understand that spine is measuered on a 28" span and that you add or subtract approx 5lbs per inch under or over to get the right spine at your draw length.So for a 45lbs bow with a draw of say 30" I need to get shafts spined at 55lbs. Do you also have to adjust for arrowhead weight, if so does anyone know the formula for this?

[n2everythg]

shooting my primitive bow I dont mess with calculating that close. I did bare shaft a few in the beginning to see what flew fine. But for me I cut my arrows 31.5 " for my 29.5 draw. And I spine them right at the bow weight or real close.
Think the last set I made up for a 42 lb bow I spined up at 45 and they shoot great.
I have heard you need a weaker spine for non center cut. but this seems to work for me. Maybe I end up with less spine for my longer arrows..... ?
Hope this helps.
n2

[Pat B]

Hardwood shoots and cane are more spine tolerant than parallel shafts because of their natural  taper and because cane recovers so quickly it seems to be even more so.
   Store bought spined arrows are for a 28" arrow with a 125gr point. A spine tester has upright that are 26" apart for measuring a 28" arrow. Each inch over or below the 28" you can subtract or add 5# of spine weight.
      For a selfbow pulling 40#@30" I would say try 40# to 45# full length shafts.      Pat

[adb]

Finding arrows that fly well from a primitive longbow, is a process of experimentation. The spine charts are a guide... a place to start. Some general rules: go up or down 5# of spine for every inch > or < 28" OAL. If you want to increase spine, go with a lighter head, or shorter shaft. Vice versa to decrease spine. Recurves require increased spine. Centershot bows are more forgiving of various spine weights... non centershot selfbows are not, and usually require 5-10# lower spine. A FF string will usually require increased spine. The bottom line? You have to try different things. Even how you fletch your arrows will make a difference. Example... I just started shooting a bbo recurve, 60" NTN, 50# @ 28", partial centershot. The best arrow flight was with 28" 70# spined arrows, 4.5" 3 fletch, and 125g head. Arrow flight is perfect. No porpoising or fishtailing.

[agd68]

Thanks for the info guys.