View Full Version : Arrow Spine Consistency, Tuning for Tighter Groups.

Barry O'Regan
09-16-2011, 05:14 AM
Arrow Spine Consistency, Tuning for Tighter Groups.


There are three debates amongst archers on the spine stiffness area on an arrow.

The Question:

1) Is the stiffest part of the arrows static spine under the manufacturer label?

2) Do all arrow manufacturers place the cock vane over the stiffest (spine) part of the arrow?

3) Do rotating the nocks determine the stiffest part of the arrows spine, when the arrow is in dynamic motion?

Answer, No, No and Yes in that order!

The Test

This test will show you various arrows I will use and where the nock location will indicate on the arrow surface area which gives the best arrow groups out to 40 meters. This test will also indicate the most consistent spine stiffness from arrow to arrow manufacturer in which to affix your cock vane.

Don't Nock it, until you tried it!

All arrows will be using an adhesive Bohning Nock Position Indicator with gradient adjustments from 1 to 4 to show me the exact location of the nock in relation to the arrow in order to see where the consistency of the spine is finally located. By turning the nock a turn on each arrow should eventually see me getting a tight arrow group at 40 meters, thus concluding this is the best spine consistency from arrow to arrow!

Nocks from most manufacturers have a raised line on the shank which I will correspond with the Bohning Nock Marked Gradients located on the end of the arrow.

The Nocks raised line can then be lined up with the Nock Indicator Gradients and used to consistently to determine where to affix your cock vane on the end of the arrow later on with the help of marking the arrow shaft with a black sharpie.

The Arrows and Spine Range

I will shoot a set of four arrows with each set from different arrow manufacturers at 40 meters and adjust the nock a quarter turn at a time thereby rotating the arrow and shooting the arrow to see which nock location indicates the best group, thus indicate the most consistent spine from each arrow.

All arrows used in this test will be within the same spine (350-400) range for a 60 pound bow, though some arrows will be longer by a few inches and or heavier by up to 100 grains.

The test will use the most popular arrows such as the Easton Powerflight, Easton Fatboys, Gold Tip Hunters, PSEX-Weave, Bemans, Victory Arrows, as well as the Victory Nanos (Now calledVAPs).

All arrows will be tipped with Martin Archery 100 grain screw in field points.

Vanes and Feathers

The test will be based on the more popular used Vanes and Feathers such as Bohning Blazers, Bohning X Vanes, Duravane, AAE Vanes,TrueFlight and Gateway Feathers.

This way everyone's favorite vane or feather is included so compound and recurve bow, release and finger shooters can benefit.


Keep in mind this test is not to determine the best arrow, vane, feather or point. This test is to find the most consistent part of the spine which will give the best arrow grouping.

Since these arrows are all of varying manufacturers, design, length and vanes, I will be using my 40 meter pin sight and not all arrows will be hitting the gold. For me to adjust my sight for each arrow set of varying size and weight arrows to hit the gold I would have to spend two days doing this test.

Again, we are going for best group, for accuracy into the gold I leave that up to you fellow archers to adjust your pin sights to do that!

(It is assumed all arrow manufacturers (with the exception of PSE's X-Weave carbon arrows) are consistent in their manufacturing process in placing the stiffest or consistent part of the spine in the same location for every arrow to date).

The Issue of Nock Tuning

The problem with nock tuning is vane clearance when you rotate the nock in which the vane may contact any rest that is not a full dropaway, hence the popularity of dropaways.

For this test, I replaced my Spott Hogg Infinity Blade Rest to a Dropaway rest which offers total vane clearance and no vane contact. This is especially critical when rotating nocks at varying degrees when trying to determine the stiffest part of the spine while getting no contact vane clearance. Once I get consistently tight groups, I strip off the vanes and put new vanes to correspond where the spine on the arrow is consistent. I then takeoff my Dropaway rest and put my Spot Hogg Infinity Blade Rest back on.

This test will allow archers whether they use a trigger release or fingers to fletch their vanes to their arrows and tune for best performance. If all things being equal this test should show the location where to place your cock vane over the stiffest or most consistent part of the arrows spine, without having to resort to changing their arrow rest like I have done to gain total vane clearance.

Spine Testers

While you could use a spine tester and you can also take up badminton and wear lacy pink socks too!

I noted a few things that spine testers "Bless their cotton socks" do not or cannot determine, though no fault of their own, they measure static spine, not dynamic spine.

Spine can vary along the shaft, so I took a few carbon arrows into my lab and cut them into exact 1 inch increments and weighed each 1 inch section to determine if all equal lengths weighed the same. The answer, out of 30 sections of cut 1 inch carbons measured end to end with a digital micrometers 3 sections weighed the same out of 30 sections the rest of the sections weighed up to 3 grain more than the others. So you can see why field testing for dynamic spine is the better way to judge an aggregate stiffness of the entire arrow.

Spine testers I have used in the past do not determine best arrow grouping, only field testing will determine that. Some spine testers I've found have inaccuracies in which I will not go into, let's just say spine testers are good for wood arrows and leave it at that!!

You should know carbon arrow spine can have various spine differences in a dozen arrows of the same set, even Easton X-10s may have one or two arrows in a set of a dozen arrows that are not matched. So there is nothing like true field conditions to see how arrows group at 40 meters when dealing with these carbon spine consistency anomalies. After all isn't great groups what it's all about, followed by sighting adjustments for great accuracy?

Once I attained the best arrow group possible using the Bohning Nock Position Locator, I let another archer shoot all the "newly tuned arrows" to determine if he would also get all arrows to group good and tight.

Barry O'Regan
09-16-2011, 05:15 AM
Below the accompanying photos will show the best grouping at 40 meters using various arrows.

The left photo will show the end result of the best arrow group.

The right photo will show the exact location where the stiffest part of the arrow spine is located and whereto affix your cock vane for best groups.

Easton Fatboy Arrows with TrueFlight Feathers (Parabolic)

Easton Powerflight Arrows with Bohning Blazer Vanes

Easton Powerflight Arrows with AAE Plastifletch Vanes

PSE X-Weaves Arrows with Gateway Feathers Shield Cut

Victory V Force HV Arrows with Bohning Blazer Vanes

Victory Nanos Arrows with Bohning X Vanes Shield Cut Vanes

Beman Arrows Made in France with Gateway Feathers Shield Cut

Gold Tip Arrows with TrueFlight Feathers Shield Cut


Once I adjusted the nock position using the Bohning Nock Position Indicator (Bohning Nock Indicator not yet for sale) on each and every arrow to attain the best arrow group, I photographed the results and posted the photos below.

While all big name arrow manufacturers produce great arrows to meet every archers budget,

PSE X-Weave arrows seem to standout unlike other carbon arrow manufacturers who have an overlapping seam along the length of their arrows. It is said this is the stiffest or most consistent arrow area on the carbon arrows spine.

PSE X-Weave are exactly what the name means,the carbon fibers use a weaving process whereby they are woven around the carbon arrow, hence no seam and it appears the X-Weave arrow groups at varying distances show no matter how you adjust your nock, the stiffness seems to be consistent all around the arrow and accurate.

A lot of fine tuning can also get you the best groups, some also prefer helical, straight or offset to shooting form, notwithstanding and assuming your Form is darn near perfect, carbon arrows in particular have a varying spine range say for example a 400 spine arrow for a 55# to 60# draw weight for instance has a spine range of e.g. .380-.410, you may find the arrow performs better at a certain length e.g. 29.5 vs 31 inches +/- and a draw weight sweet spot e.g. 56# vs 60# +/-. Shooting for consistency after your tuning trials and error, such as walk back tuning will show you the ultimate results of your efforts.

At least this write up will inform those wondering about spine consistency and how a fletching along the imaginary parting line along and arrow, with slight nock adjustment can get your arrows grouping where you want them, whether you use points or broadheads.

I am also assuming each batch of arrows present and future will have their spines within the same location and the ones in this test.

Please refer to the field test photos below!

Please keep in mind, I am testing for grouping, not accuracy, as all arrows tested have different weight characteristics, thus dialing in for accuracy for each set of arrows for accuracy would take more time dialing in my sights for accuracy, which would take more time than I am willing to give for this test.

I did however adjust our draw weight 1-2 pounds +/- to determine the arrows sweet spot in relation to my draw weight. (Think of it as a vehicle, best RPM range to wheel Brake Horsepower ratio)

Barry O'Regan
09-16-2011, 05:18 AM
Please remember I am shooting at 40 meters for groups not accuracy.

Barry O'Regan
09-16-2011, 05:21 AM
An unexpected Robin Hood at 40 meters!

Barry O'Regan
09-16-2011, 05:23 AM
Actually in all fairness to PSE, it did not matter one iota which way I positioned the nock on the arrow, as grouping was consistently tight, scary tight slapping the arrows together hard.

Barry O'Regan
09-16-2011, 05:24 AM
Using HV 400s

Barry O'Regan
09-16-2011, 05:26 AM
It would have been nice to get some Easton X-10s to test as well, but finances are tight, perhaps another time.

Barry O'Regan
09-16-2011, 05:28 AM
These Beman arrows were once a product of France, before Easton bought them out in the 1990s.

Barry O'Regan
09-16-2011, 05:29 AM
Gold Tips a favourite for hunters in the lower mainland of BC.

Barry O'Regan
09-16-2011, 05:30 AM
What readers will notice, is with a little trial and error, all arrows regardless of manufacturer give pretty tight groups with a little nock tuning.

I have refletched these arrows where the parting lines are indicated in the photos and gone back to my infinity blade rest, and arrow groups are nice and tight, with very minor nock tuning involved.

Barry O'Regan
09-16-2011, 05:46 PM
If all arrows are fletched in exactly the same spot for a dozen arrows, you will get respectable groups and arrow flight. What I am trying to inform readers is that fine tuning for best arrow flight and groupings as well. Like I mentioned arrow with particular spines do seem to enjoy a sweet spot when it comes to a particular draw weight, with carbon arrow have a .30-40 spread, I find it best to also adjust the bows draw weight till I get the best and consistent arrow group.

I have heard some great things about Harvest, unfortunately in our neck of the woods they have not caught on, but if I happen to see some in the pro shop, I am more than willing to pick up a dozen and give me a try and perhaps write a review with photos on Harvest Arrow performance. I will be writing a review on Dark Horse Arrows once by buddy lends me a dozen of his. Dark Horse Arrows are made in Canada, I think on Vancouver Island and are said to closely resemble CX s. But until I get my hands on some, I won't know.

What I am going to be ordering are Easton's Max Carbons 2712, a tree trunk for line cutting in 3D. Looking forward to getting my hands on those and writing a review.

Again thanks Sonny for the comments, greatly appreciated.


09-17-2011, 02:08 AM
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Barry O'Regan
09-17-2011, 03:47 AM
I'm thinking if it was that important manufactures would put a line on the arrow and say 'put vane here' or something similar. What is the actual difference in between the seam and the rest of the shaft? I'm betting its next to nothing in real world terms.

You know in a perfect world with all things equal, in that if one were to fletch and align their vanes on the same area of each shaft it would most likely be okay for stump shooters and plinkers. But for hunting, especially BroadHeads and FITA and 3D tournament, finding the sweet spot for the arrow is a tried and true approach many top archers use to get that last extra point or increase their chances at getting that game animal. Much like fine tuning a stock automobile from the dealership, while both vehicles will get to from point A to B, a fine tuned car will get you there faster and corner better. Arrows finely tuned will allow the bow to make the best use of it's shooting properties and guide the arrow more efficiently and accurately.

09-17-2011, 02:35 PM
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09-17-2011, 06:50 PM
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Barry O'Regan
09-18-2011, 02:36 AM
Yes, but nock tuning has been around for quite some time. I would consider this more of a refresher course taken a step farther.

I would have chosen another arrow. Victory X Ringer HVs perhaps. Or even Victory X Killers. I sold my X Killers before I even tried them - guy just had to have them and paid the price. I set them for him, nothing fancy. One hour later, with very little sighting in, he nailed a indoor 299/300 with 48 Xs. Hate to compete against him when he fine sets his sights.

I have X Killers, I am known to have more arrows than god! I buy em, try em, review em. X-Killers are nice, I just like trying other arrows on the market as part of my review.