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Arrow Spine Question

780 Views 2 Replies 2 Participants Last post by  ButchD
What are the variables that affect dynamic spine? What I'm calling dynamic spine, is how the arrow actually behaves when shot. I'm presently shooting .750 acc's,
29" nock to end of shaft, 100g glue in Easton parabolic points, holding 34# @ 29.5" on my target bow. When I look up my rig on the Easton site, the shaft selector for target has me using a .650 to .670
spine shaft, and I'm on the stiff end of the selection, so about a .650. I'm slightly stiff on my bareshaft tuning with the .750's. I arrived at this selection using Vipers advise, and more trial and error than there's room for in this post. I know the efficency of the limbs plays a role in dynamic spine, a 34# limb that shot an arrow significantly faster from my bow would require a stiffer arrow. I set up my centershot with the point of the shaft on the left side of the string, I'm RH, medium plunger setting. I know from shooting bareshafts that theye are a good indicator of release problems, lol, so would a consistent release problem affect dynamic spine? Are my limbs, W&W Everest Pro's, too slow for the chart to be accurate? I'm contemplating a move to lighter limbs, and am financialy unwilling to get into an arrow selection debacle. Thanks to all!
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Many things impact the dynamic spine

What are the variables that affect dynamic spine? What I'm calling dynamic spine, is how the arrow actually behaves when shot. I'm presently shooting .750 acc's,
29" nock to end of shaft, 100g glue in Easton parabolic points, holding 34# @ 29.5" on my target bow. When I look up my rig on the Easton site, the shaft selector for target has me using a .650 to .670
spine shaft, and I'm on the stiff end of the selection, so about a .650. I'm slightly stiff on my bareshaft tuning with the .750's. I arrived at this selection using Vipers advise, and more trial and error than there's room for in this post. I know the efficency of the limbs plays a role in dynamic spine, a 34# limb that shot an arrow significantly faster from my bow would require a stiffer arrow. I set up my centershot with the point of the shaft on the left side of the string, I'm RH, medium plunger setting. I know from shooting bareshafts that theye are a good indicator of release problems, lol, so would a consistent release problem affect dynamic spine? Are my limbs, W&W Everest Pro's, too slow for the chart to be accurate? I'm contemplating a move to lighter limbs, and am financialy unwilling to get into an arrow selection debacle. Thanks to all!
Well, I'll take a stab at this, and I'll probably miss several things -
1. Yes, your release will affect the dynamic spine (may be one of the most important items)
2. Yes, your plunger tension will affect the dynamic spine
3. Yes, limb speed will make a difference
4. Brace height affects the dynamic spine (higher brace height = weaker dynamic spine)
5. Point weight (heavier = weaker dynamic spine)
6. Nock and fletching weight impact it (the heavier the fletching and nock the more stiffly the dynamic spine will react)
7. Nock tightness (tighter nock = stiff dynamic)
8. Fletching location (closer to the nock = weaker dynamic)

This is a good start. With my set-up, the easton charts typically result in me having weakly spined arrows. I currently shoot W&W Winex limbs and N-Apecs limbs, and in my experience, these fast limbs seem to make a significant impact on the dynamic spine, vs. say old Hoyt Carbon Plus limbs of the same weight @ the same draw length.

Regarding your release problem, I've noticed both with myself and several students, that if you anchor with the string nearer the tips of your fingers, it will often make the bare shaft act stiffly. A deep hook with a very relaxed release can, in some instances, give a better representation of how the arrows should be behaving. I say "in some instances" because I've also witnessed unbelievably excellent shooters, shooting out on the tips of their fingers, with very relaxed releases. But this final paragraph just goes to further illustrate just how much impact your release can have.
 

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Dynamic spine

Well, I'll take a stab at this, and I'll probably miss several things -
1. Yes, your release will affect the dynamic spine (may be one of the most important items)
2. Yes, your plunger tension will affect the dynamic spine
3. Yes, limb speed will make a difference
4. Brace height affects the dynamic spine (higher brace height = weaker dynamic spine)
5. Point weight (heavier = weaker dynamic spine)
6. Nock and fletching weight impact it (the heavier the fletching and nock the more stiffly the dynamic spine will react)
7. Nock tightness (tighter nock = stiff dynamic)
8. Fletching location (closer to the nock = weaker dynamic)

This is a good start. With my set-up, the easton charts typically result in me having weakly spined arrows. I currently shoot W&W Winex limbs and N-Apecs limbs, and in my experience, these fast limbs seem to make a significant impact on the dynamic spine, vs. say old Hoyt Carbon Plus limbs of the same weight @ the same draw length.

Regarding your release problem, I've noticed both with myself and several students, that if you anchor with the string nearer the tips of your fingers, it will often make the bare shaft act stiffly. A deep hook with a very relaxed release can, in some instances, give a better representation of how the arrows should be behaving. I say "in some instances" because I've also witnessed unbelievably excellent shooters, shooting out on the tips of their fingers, with very relaxed releases. But this final paragraph just goes to further illustrate just how much impact your release can have.
gigem 99
thanks for stepping up. As you aptly stated, there are a number of variables which can have an affect on dynamic spine. I've noticed when shooting bareshafts, that, especially when I start shooting, my less than perfect releases seemed to make the bareshafts behave stiff. As a relative beginner, I'm succeptable to relapses without prior notice. When I'm tending one part of my form, anything can go amiss. lol. Without a way to measure arrow speed, a major factor of dynamic spine, limb efficency, goes unknown. Release is at the top of my to do list. Every time. lol.
 
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