Arrow Spine Consistency, Tuning for Tighter Groups.

By Barry O'Regan - Bohning Pro Field Staff, Bohning Staff Shooter, T.R.U. Ball Staff Shooter.

 

Summary

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

The Question:

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

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

3) Can rotating the arrows nock assist in finding the stiffest part of the arrows spine?

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 ¼ 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 such as Bohning Nocks have a raised line on the shank which I will correspond with the Bohning Nock Indicators Marked Gradients located on the end of the arrow.

The Bohning Nock raised line canthen be lined up with the Bohning Nock Indicator Gradients and used to consistentlyto determine where to affix your cock vane on the end of the arrow later onwith 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.

Caveat

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

Spine testers I have used in the past do not determine dynamic spine when an arrow is in flight, which will give me the best arrow grouping, only field testing will determine that. Spine testers are good for wood arrows and I will 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.

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

Conclusion

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.

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 than I am willing to give for this test.

Easton Fatboy Arrows equipped with TrueFlight Parabolic Feathers.

Easton Powerflight Arrows with Bohning Yellow Blazer Vanes and AAE Plastifletch Purple Vanes

PSE X-Weaves Arrows with Gateway Feathers Shield Cut.

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.

 

Victory V Force HV Arrows with Bohning Blazer Vanes

Victory Nano Arrows with Bohning X Vanes Shield Cut Vanes

Beman Arrows (Made in France) with Gateway Feathers Shield Cut.

Gold Tip Arrows with True Flight Feathers Shield Cut