Spine...not trying to beat a dead horse, but.....

[JARRETT]

Good morning all!!!

Im still new to the site, been a member for less than a month, and extremely green at this thing called Traditional archery.  I'm still working on the basics such as shelf material, side plate, brace height, nock point, and spine...which brings me to my question.  I have found two different ways to measure/calculate arrow spine.

I found this one at:

 http://www.eastonhunting.com/blog/making-sense-of-arrow-spine

Arrow Spine

The spine rating of an arrow is simply a measurement of its stiffness. The same Easton arrow comes in a variety of stiffness: the lower the number, the stiffer the arrow. For example, a 330 arrow is stiffer than a 500 spine arrow. There are two kinds of spine (stick with us, we promise not to get too technical). There’s static spine, which is how an arrow reacts when an 880-gram (1.94 lbs.) weight is suspended from the center of the arrow. The arrow must be 29” in length and supported by two points, which are 28” apart. The number of inches the arrow deflects or bends X 1000 due to the weight is the spine size or measurement of an arrow. So, a 500 arrow bends .5-inches when the weight is applied.


and that seems to be the standard on all of the other sites as well.  Well this morning at work(I work in the oilfield in South Texas and its been pretty slow lately)I'm cruising on the 'ol Google machine and come across this article on:

 http://www.alaskabowhunting.com/Matching-Arrows-W16.aspx

What is spine?
Spine is a measure of stiffness. How much backbone does that arrow have? That is correct-spine as in backbone, not ”splines” which are a series of ridges and grooves that allow multi-piece drive shafts to fit together to transfer power to the wheels of your pick- up (Sorry, incorrect terminology is a pet peeve of mine). Long ago W. J. Rheingans and Forrest Nagler worked out a formula for measuring arrow stiffness. Most arrow makers use spine charts to sort out their shafts into various categories but the formula used to make that confusing chart is simple. 26 divided by bow poundage gives you the deflection in inches (usually a fraction of an inch) of a matched shaft. Deflection? Yes.


So yeah, now im a bit confused.....is the Easton guide for compound shooters? And the Alaska bowhunting site for Trad?  I figured that the same formula (weight suspended from the center of the arrow, length of arrow, distance between suspension points)would be used for both.  Am I missing something?  One more question while I have you collective ears twisted....What if I'm shooting a 31" arrow?  Do I move my supporting points out to 30" apart?   Am I overthinking this?  I tend to get a bit OCD...about everything.

I certainly appreciate the help.  If this question has already been asked I apologize.  I did search for it.

-Jarrett

[SCATTERSHOT]

Easton spine charts were developed for compond bows, amd you will find their recommendation stiff for a traditional setup.

The spine is for a 28" arrow. For a longer arrow, such as your 30"er, you will need a stiffer spine shaft to compensate. Typically 5#/inch is a good place to start.

All bows are different in the amount of centershot (how close the arrow pass is to the center of the bow), efficiency of the bow itself, amd fastflight versus Dacron string material and the weight of the point you are using, for example. There are other factors that enter in to it, but that should get you started.

Good luck!

PS... Forgot to mention that if you will post the specs of your bow and your ACTUAL draw length (have someone measure it for you) guys here will be happy to,help you in selecting the proper shaft.

[SCATTERSHOT]

Duplicate post, sorry.

[BAK]

The Easton chart was not developed for compounds.  It was developed for their aluminum arrows before compounds ever came along.

Your first is for aluminum's, and MAYBE carbons.

The second is for woods.

[VA Elite]

can you tell us what your specs are?

draw length, draw weight? style of bow? carbon, Alum, wood arrow? And yes, you way overthinking this. In my opinion.

[JARRETT]

scattershot, I appreciate the info, but confused by what you mean on 5#/inch?

bak, wood arrows never even crossed my mind!  Noob mistake!!

VA elite, I'm shooting a Grayling Kodiak Hunter, 45x#'s, 27-3/4" dl, carbon, and I knew I was over thinking it!!!

[McDave]

I don't think you are overthinking it at all.  If you enjoy reading and learning things about traditional archery, there's a world of information out there waiting for you.  Some of the things we read are helpful and some aren't, but it is hard to know what will be helpful and what won't in advance.

There are two types of spine: static and dynamic.  Static spine is what is measured by the Easton chart.  Different companies measure static spine different ways.  For example, Gold Tip might state that an arrow has a spine of 3555, meaning it can be used by bows from 35-55 pounds (this is not always true, by the way, and will vary among bows).  However, most of them will also give you a conversion to the Easton measurement, which is becoming the standard.  For example, a 3555 Gold Tip arrow has a .500 spine.  It is useful to know that if a .500 spine arrow from one company works well for you, a .500 spine arrow from another company should also work well.

Then there is dynamic spine, which is what the arrow does after being shot.  If you have a 30" draw, and want a 31" arrow, you will want an arrow with a stiffer dynamic spine than someone with an otherwise identical bow who shoots the same poundage with a 28" draw who wants a 29" arrow, because a longer arrow weakens dynamic spine, as does increasing point weight.  That is why Gold Tip can mark its arrow with such a broad weight range, for example, from 35-55 pounds.  Sure, you could shoot that arrow in a 35 pound bow, but you might have to put 200 grains on the front to get the arrow to fly right, or you could shoot it in a 55 pound bow, but you might have to put a 100 grain point on the front to get it to fly right, which is probably the opposite of what you would like to do.

Anyway, there is a lot to learn about static and dynamic spine, and for me, it is part of the enjoyment of archery to learn these things.  Traditional archery is a big tent, and if you don't like to get bogged down in the details, that's fine too.

[VA Elite]

Mcdave and others have PHd's in this stuff so I will let them take it from here. I just know that the many archers on here helped me get in the game last year. I have improved greatly over that time and so has much of my knowledge. go get it brotha!

[McDave]

Your draw length is close enough to 28" that let's just call it 28".  If you're just getting started, it probably will be 28" soon, as you learn to expand more.  This is convenient as that's the way most bows are marked, and you don't have to do a conversion to a different draw length.

To cut through it, if you want a good arrow to start with, either try a 1916 aluminum, a .500 spine carbon, or a 45-50# wood arrow.  Have the arrows cut to 29" and start with a 125 grain point.  Some of these things may change down the road as you shoot more and learn more about arrow flight.

[VA Elite]

^^^^Exactly what I did. I told you these guys are sharp!

[AZ_Longbow]

i have a pine test kit, 2 arrows from the company and type i will shoot. right now it is gold tip velocity full length of each spine, all bare shaft.
then a full test kit of point weights, 2 of each from 75gr up to 300gr. once i find the closest spine with the weight i am wanting i then buy dozen and cut 2 of those. one of them always cut before the other, in case i go to far i only want to ruin one. i never got the calculators to work, and the charts never did either. every bow , even bows made alike, may want a different arrow. can't force the bow to change much, but you can change the arrow.

[JARRETT]

I certainly appreciate the info guys!  McDave, you are a wealth of knowledge!!  I'm needing to order arrows and this certainly helps me out.  Currently I have 5 Trad arrows, and they do not match(I know, I know).  But I wanted to clear things up a bit before I bought new ones. Three are Gold Tip .500 traditional arrows, 32", 8.6 GPI. And I have two Easton Axis Infused Carbon .500 31", 8.9 GPI.  The Eastons seem to fly pretty good with a 125gr field point.  I cant seem to get the G.T.'s to fly worth a darn with any tip.  pretty good left to right, but always low....

[McDave]

If you're using the arrow tip to aim, you could be hitting low with the GT's because of the longer length. Either that or they somehow got heavier than the Eastons, even though they are marked lighter. At some point, it would be useful to get yourself a grain scale, so you could verify that all the arrows in the bunch you're shooting are close to the same weight.  Sometimes you get an oddball arrow, even though it's marked the same as the others.

If you are new to this trad stuff, pick a good bow you like and stick with it, until you have everything working for you.  Your draw length may settle down to something a bit shorter.  Your trad draw and your cp draw will be different and it will be slightly different with any different grip, it is what it is, but with carbon arrows it still important to know what that draw length will be when you are actually shooting with your proper form.  Targeting a draw length prior to developing your personal set form can get one ending up with some very stiff arrows and adjustments will need to be made to those arrows.  Most of the time guys that I talked out of using cps and guns ended up with shorter draw lengths and needed to add point weight down the road.   The reason for not jumping around with bows is that they are all different. Example, I had a 36 and a 42 pound Black Widow bows. I always wanted a Bear Kodiak, I got one, 50 pounder.  I expected that it would need Bear 308s.  It did, but not with Bear broad heads,  too stiff.  My 42 BW target bow shot them fine and was noticeably faster than the Bear.  I put heavier heads on the 308s, the larger DeadHeads, better.  The 42 pound target bow shot them as well and still noticeably faster.  Some bow designs are just flat out faster than others.  It can really mess with your basic development.

[JARRETT]

I bought me a scale this past weekend.  I do aim with the point of my arrow.  Let me rephrase that.  Im trying to aim with the point of my arrow.  And I have settled on this bow

[McDave]

If you're aiming with the point of the arrow, then all your arrows need to be the same length in order to hit in the same spot, at least as far as that one variable is concerned.  You can adjust to different arrow lengths, but you would have to separately test each length to see where it hits.  Of course, the same thing often happens when you switch bows, unless they both just happen to have the same cast.  I personally see no reason to use different arrow lengths, as there are enough separate variables to remember anyway, since I do like to switch bows from time to time.

If you are referencing to the arrow, don't look straight at it.  When I try to teach indirect aiming, i found that putting a bright red ball on the ground about where the point the arrow would be helps.  The steadier the eyes are focused on the spot you want to hit, the easier it is to tell where the arrow is.  The red ball saves painting and putty work on my garage.   It also helps to simply practice pointing an arrow with out actually drawing the bow with it.  One can indirectly see if it is on plane etc. to be heading towards its mark.  You can practice eye control by simply pointing your finger at stuff without looking directly at it, then do that with and arrow that would be in a closer position to how it would be if you shooting at something.   In time this becomes so automatic that it is basically instinctive with some acknowledgement of the arrow.  That is one of the biggest reasons to stick to one bow and one arrow set up, until things get grooved in.

[McDave]

Originally posted by pavan:
If you are referencing to the arrow, don't look straight at it.  When I try to teach indirect aiming, i found that putting a bright red ball on the ground about where the point the arrow would be helps.  The steadier the eyes are focused on the spot you want to hit, the easier it is to tell where the arrow is.  The red ball saves painting and putty work on my garage.   It also helps to simply practice pointing an arrow with out actually drawing the bow with it.  One can indirectly see if it is on plane etc. to be heading towards its mark.  You can practice eye control by simply pointing your finger at stuff without looking directly at it, then do that with and arrow that would be in a closer position to how it would be if you shooting at something.   In time this becomes so automatic that it is basically instinctive with some acknowledgement of the arrow.  That is one of the biggest reasons to stick to one bow and one arrow set up, until things get grooved in.

Good explanation!

[SCATTERSHOT]

Originally posted by JARRETT:
scattershot, I appreciate the info, but confused by what you mean on 5#/inch? it!!!

I was thinking wood arrows primarily, but say you need a 30" arrow (doubtful). To accomodate the extra length, you would  add 10# to the spine of your arrow. Just a rule of thumb, but that's the general idea.

[JARRETT]

Originally posted by pavan:
If you are referencing to the arrow, don't look straight at it.  When I try to teach indirect aiming, i found that putting a bright red ball on the ground about where the point the arrow would be helps.  The steadier the eyes are focused on the spot you want to hit, the easier it is to tell where the arrow is.  The red ball saves painting and putty work on my garage.   It also helps to simply practice pointing an arrow with out actually drawing the bow with it.  One can indirectly see if it is on plane etc. to be heading towards its mark.  You can practice eye control by simply pointing your finger at stuff without looking directly at it, then do that with and arrow that would be in a closer position to how it would be if you shooting at something.   In time this becomes so automatic that it is basically instinctive with some acknowledgement of the arrow.  That is one of the biggest reasons to stick to one bow and one arrow set up, until things get grooved in.

Thanks bud!!!  Awesome stuff!  I will certainly be trying this.  

McDave, the only reason I am currently shooting two different length and size arrows, is that's all I got right now, lol.  I think I'm going to end up going with the G.T. traditional 500's at 29".  I'll gladly take any and all advice you guys have, I'm a d@mn good listener!!!