# Arrow Spine Testing



## JimPic (Apr 8, 2003)

For me,spine testing is critical.I spine test every shaft I buy to make sure they're in the right poundage.I shoot barebow so those arrows must hit where I'm looking.Too heavy of a spine and they'll hit left--too light and they hit right.With a sighted bow,the advantage is you can adjust your pins to where the arrow is hitting as long as the arrow is flying straight.I'm suprised alot of pro shops don't have spine testers in shop-IMO they're a very valuable tool.


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## nuts&bolts (Mar 25, 2005)

*Not sure what you mean by spine test?*



Lance70 said:


> How important is it to spine test your arrows and why? And do spine tested arrows promote better arrow flight,grouping,acuracy? Considering your aim is very consistant. Hopefully this question makes sense to anyone.
> 
> Thanks for any feedback!


What do you mean by spine test? A spine tester is a very expensive piece of equipment. It requires a very accurate dial indicator, and a reference standard two pound weight, two supports and typically roller bearings.

Some people will "float their arrows" to find the heavy side of the shaft.

Other folks will "index their nocks" on bareshafts to find the best rotational position of the nocks to get the smallest groups. Essentially, indexing nocks is "spine testing" your arrows because dynamic spine does vary depending on the nock orientation for each arrow shaft.

So, yes, group tuning bareshafts prior to fletching the shafts will give you better groups, presuming your skill level is sufficient to fire bareshafts consistently. A bareshaft has zero steering correction, so you need a high level of skill for this technique to work, otherwise it will drive you crazy.

If you do decide to index your nocks with a bareshaft, then you need to weight match the arrow shafts, fletching, nocks, nock bushings, and points.

If you go through all this trouble, you will find that your arrows can group tighter, than if you didn't go through this trouble.

The next level would be a custom sized center serving to get the optimum nock to center serving fit.

This presumes, of course, that your bow is tuned to perfection: creep tuning, walkback tuning, tiller tuning, paper tuning, bow balance, arrow rest tension, etc.


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## nuts&bolts (Mar 25, 2005)

*Fingers shooters vs release shooters*



JimPic said:


> For me,spine testing is critical.I spine test every shaft I buy to make sure they're in the right poundage.I shoot barebow so those arrows must hit where I'm looking.Too heavy of a spine and they'll hit left--too light and they hit right.With a sighted bow,the advantage is you can adjust your pins to where the arrow is hitting as long as the arrow is flying straight.I'm suprised alot of pro shops don't have spine testers in shop-IMO they're a very valuable tool.


Jim:

Sounds like you are a fingers shooter. Yup, spine is extremely important for a fingers shooter. You need to combat archer's paradox by selecting the proper spine and then fine tuning with a plunger button.

Based on Lance70's signature block, he is a release shooter. Release shooters don't deal with archer's paradox, but they do need to select an arrow with the proper spine to a degree depending on the type of archery.

Long range FITA shooters prefer the X10 shafts due its wind drift resistance and generally want a higher FOC with a 120 grain tip. A FITA shooter generally will pick a X10 shaft with the "proper spine" or stiffer.

3D shooters want the fastest lightest arrow possible right at the 5 grain per pound of draw weight limit. These folks also want the proper spine, but are willing to go with a lower FOC due to the short to medium distances (less than 50 yds),

NFAA field archers shoot from 10 yds up to 80 yds. A medium weight arrow with 12-15% FOC and the proper spine are the recommended way to go.

Indoor spot shooters usually want the line cutting ability of the fat aluminum shafts or the fat carbon shafts. Here, proper spine goes out the window and usually folks resort to empirical testing. They start with full length shafts and experiment with low draw weight (40-60 lbs) and tip weights from 120 grains up to 300 grains or even more in some cases.

So, spine is always taken into consideration to some extent for release shooters.


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## swbuckmaster (Dec 20, 2005)

I believe the dynamic spine of your arrow is more important than the actual spine of your arrow. (Don’t shoot an under spined arrow!) The dynamic spine is what happens to your arrow when you shoot it. I try to get every one of my arrows to flex the same way out of my bow when shot. I call this tuning my arrows. You can only do this if you can see your arrow flex. This can only be done if you have really good and consistent form. I shoot an arrow through paper and get it to bullet hole though paper. I than shoot my next arrow and turn the nock until I get it to bullet hole. This usually takes up to 5 shots. The only way I now of to tune the bigger fatter arrows with really hard spines is shoot them through a hooter shooter and twist the nocks until they all hit the same hole. I than mark the bushing so the dynamic spine can be located again if needed. Hope this helps


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## JimPic (Apr 8, 2003)

nuts&bolts:

I am a finger shooter and that's why I said it was critical for me to test my arrows.It took me quite a while to find the right spined arrows but once I did-things really started to come together.It makes absolutely all the differance in the world for my style of shooting.


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## nuts&bolts (Mar 25, 2005)

*Yup, dyanamic spine is very important*



JimPic said:


> nuts&bolts:
> 
> I am a finger shooter and that's why I said it was critical for me to test my arrows.It took me quite a while to find the right spined arrows but once I did-things really started to come together.It makes absolutely all the differance in the world for my style of shooting.


Yup, I agree. I also shoot target recurve and I fine tune my arrows with custom weighted tips. It's not hard to do. Use a digital scale, some archery software (OnTarget2!) to get you in the approximate tip weight and arrow spine, and then start adding solder wire and heat over a stovetop. You can also pop in a cut piece of finishing nail and a dab of hot melt glue. I weight match my arrows to 0.2 grains. 

I may build a spine tester some day, but for now, weight matching arrows and indexing nocks on bareshafts gets the job done for me.

Yes, the dynamic spine makes a huge difference in how tight your groups are.


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## Lance70 (Jul 12, 2005)

Thanks for the feedback gentlemen, you answered my questions and then some.:thumbs_up


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