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Main Boards => The Shooters FORM Board => Topic started by: DJT on October 16, 2007, 03:56:00 PM

Title: SPINE HELP WHY IS THIS HAPPENING???
Post by: DJT on October 16, 2007, 03:56:00 PM
Sorry for the redundancy but i posted this in the pow wow as well but i wasnt sure if this was a shooting related issue (as it could be form) or a general so please forgive me any help would be great.
I need a bit of help.  I have been fortunate to be able to own quite a few bows and in trying to find the right arrows i seem to need arrows that would be way too stiff from what everything i know and have read here and elsewhere would dictate.
First off have a 29 inch drawlength so perhaps this is a bit of the issue but most of the bows i am shooting are on the lighter side at 29inches ranging from 50 to 60 lbs.  Most of these light bows seem to like 2219s instead of the 2018 and 2020s everyone tells me i should be shooting.  
When i shoot these bows (a border black douglas at 55# a great northern longbow at 57 a hummingbird at 55 a blacktail at 60 to name a few harrison longbow at 55) even the shortest 2219s i can shoot at my draw (say 30" to BOP) are either perfect or still show slightly weak with 125 grains up front.  2020s and 2117s shot bareshafted hit the target almost sideways at 15 to 20 yds.  
The 2219s fly well for the most part but i am surprised that bows of relatively light poundage with a slightly long but not abnormal draw length   still make these arrows show weak.  Most of the trad bow sights do not even carry aluminum arrows that are spined stiffer than this and again the bows are light.  I guess i was wondering if anyone else had an issue like this or what it could be  otherwise?  I shoot three under but that seemingly would not do much to change spine.  I want to start shooting heavier bows and it seems like i will run out of shafting options especially if i want more point weight than the 125 i have been using.
Any thoughts from you guys would be a big help because i cant get the thought that i am not supposed to get good flight from 2219s from all of these light bows.  i just want to be sure i am not loosing efficiency by shooting an arrow that has a lot of things wrong with it but only appears to be spined right because of some sort of odd kick etc.  
I really appreciate the help as always guys.
thanks
Don
Title: Re: SPINE HELP WHY IS THIS HAPPENING???
Post by: aromakr on October 16, 2007, 08:13:00 PM
Don:
You say they "spined slightly week" what is your difinition of spined week. with your draw at 29" are the bows also weighed at 29 or 28"(if weighed at 28" add about 3# to the marked weight)?

The depth of the shelf is a very important factor, industry standard is less than center by 1/8" if the shelf is center cut or past center you will need a stiffer spine. also standard for spine is 28" so your 30" shafts will be 10# lighter in spine. I can tell by the bows you mentioned that some of them are cut past center this will add another 10-15# to your spine requirement. A 2219 spines 80#@30", I would say your about right with a 55/60@28" and cut past center.
Bob
Title: Re: SPINE HELP WHY IS THIS HAPPENING???
Post by: Scott J. Williams on October 17, 2007, 07:27:00 AM
I have to agree with "Bob", you might even have some tuning issues.  I shoot bows in your weight range, to be honest I have never had anything like that happen. I had a Bob Lee, that was cut to centershot and like Bob stated, I could shoot stiffer spined arrows, but fine tuning the ones rated for my bow and draw length was worth the effort.  Make sure that when you are bare shaft testing, that you focus more on the attitude of the arrow in flight, not just how it hits the target.  There is a misconception about this, some people will never get that arrow to fly like a dart without feathers, but getting it close as possible should be the goal. Remember you will still have feathers on the darn thing when you shoot it.
Title: Re: SPINE HELP WHY IS THIS HAPPENING???
Post by: Jacko on October 18, 2007, 06:25:00 AM
Some questions if I may , is your nocking point abnormally high or your brace height too low , both sometimes go together in giving the illusion of good bow tuning for a particular arrow . Are your bows tillered for a split finger release or for 3 under - this can cause arrow flight issues , have you played with the forward of centre of your arrows - something in excess of 20% shows good results in bare shaft tuning for me perhaps a switch to timber or carbon arrows may give you more spine range to play with . Not much help but perhaps some stuff for you to play and think with . regards Jacko
Title: Re: SPINE HELP WHY IS THIS HAPPENING???
Post by: Al Dean on October 18, 2007, 08:26:00 AM
I shoot 2117s out of my bows cut to or past center.  I pull 50# @ 30" with 31" arrows and they are perfect.  I would say with your set up, if cut to center, 2219s are probably close.