Spine matching arrows

10642 Views 139 Replies 23 Participants Last post by KTownKiller, Jan 20, 2020

lostarrow

Discussion Starter · Nov 29, 2019

Lets talk about spine matching.what do you guys and gals consider a good matched set.lets use numbers for reference. I have a dozen arrows, weekest point flexing from one arrow to another. ( 1 arrow .07 )(1 arrow .08) (2 arrows .09) (2 arrows .010)(2 arrows .011)( 2 arrow .012)(2 arrows .013) so between the dozen, they very from .07 to .013 .
what does every one think.please educate me on this.
Thanks

1 - 20 of 140 Posts

Tapp-Nation

· #2 · Nov 29, 2019

First in order to spine match arrows you do not test the weak side.

The weak side of an arrow has nothing to do with spine deflection when arrows are in flight

Here is the proper process for testing spine and matching it.

Find the static stiff side, mark it and then rotate the arrow 90 degree.

Remove the weight, zero the dial gauge then hang the weight back on the arrow and take the spine deflection reading at that point only.

Reactions: 5

Martymig

· #3 · Nov 29, 2019

I have yet to start doing this. Mostly because all the arrows I've been shooting are yours Jerry and you do the work for me. But if I wanted to do this to the few Bees nd Victorys that I bought from other people, what do I need to do this ?

wb_hunter

· #4 · Nov 29, 2019

Tapp-Nation said:
Find the static stiff side, mark it and then rotate the arrow 90 degree.
Remove the weight, zero the dial gauge then hang the weight back on the arrow and take the spine deflection reading at that point only.

I'd say, take care that for all arrows/bolts, the orientation of the cocking vane vs. stiff side is identical.
E.g., put the cocking vane at the stiff side.

Tapp-Nation

· #5 · Nov 29, 2019

wb_hunter said:
I'd say, take care that for all arrows/bolts, the orientation of the cocking vane vs. stiff side is identical.
E.g., put the cocking vane at the stiff side.

Actually if you look at indexing from a physics point of view you could put the cock vane on the static stiff side or 180 degrees away.

When an arrow is in flight and dynamic spine is presenting an arrow has only two deflections. the stiff plane deflection 180 degrees through the arrow and the neutral plane 180 degrees through the arrow.

To take it a step further if we were to test an arrow dynamically we find 45 degrees to the left and right on both sides of the stiff plane it has the exact same frequency. Likewise if we were to test the neutral plane 45 degrees to the left and right on both sides of the arrow we will find the same frequency

Reactions: 3

Tapp-Nation

· #6 · Nov 29, 2019

Martymig said:
I have yet to start doing this. Mostly because all the arrows I've been shooting are yours Jerry and you do the work for me. But if I wanted to do this to the few Bees nd Victorys that I bought from other people, what do I need to do this ?

Marty you would need a RAM type spine tester. It is the ONLY accurate type of testing other than a frequency analyzer that gives a true accurate reading.
Some think you and force an arrow to roll to the proper indexing location by compressing it in a bow press. This is not correct because it will give way to the natural bend or can give way to the weak side.
As well as any tester that relies on forcing the arrow to bend and roll it will have a high rate of success but will from time to time roll to the weak side.

On a side note the neutral plane and weak side of a shaft are not the same

Reactions: 5

lostarrow

Discussion Starter · #7 · Nov 29, 2019

Tapp-Nation said:
First in order to spine match arrows you do not test the weak side.

The weak side of an arrow has nothing to do with spine deflection when arrows are in flight

Here is the proper process for testing spine and matching it.

Find the static stiff side, mark it and then rotate the arrow 90 degree.

Remove the weight, zero the dial gauge then hang the weight back on the arrow and take the spine deflection reading at that point only.

Hi Jerry
I did fallow your process to a T. those are the numbers i get on the meter.my bad for saying on the week side.
what im trying to find out is how close the numbers have to be,to be considered a good set of spine matched arrows.i know a real good set whould be if all the numbers where the same.I know you pick thru hundreds of shafts,how close do you match those spine numbers .what do you consider acceptable set of arrows.using the numbers on the dial indicator.
i hope im discribing my question properly

Tapp-Nation

· #8 · Nov 29, 2019

+/- .005 shaft to shaft is plenty tight

lostarrow

Discussion Starter · #9 · Nov 30, 2019

Tapp-Nation said:
+/- .005 shaft to shaft is plenty tight

so .005 on the plus side and .005 on the minus side.so as long as all the arrows are with in .010
im guessing mine or acceptable.they are all with in .007

Tapp-Nation

· #10 · Nov 30, 2019

lostarrow said:
so .005 on the plus side and .005 on the minus side.so as long as all the arrows are with in .010
im guessing mine or acceptable.they are all with in .007

Yes, peak to peak is .010

lostarrow

Discussion Starter · #11 · Nov 30, 2019

Tapp-Nation said:
Yes, peak to peak is .010

Good information . thank you Jerry

Martymig

· #12 · Nov 30, 2019

Tapp-Nation said:
Marty you would need a RAM type spine tester. It is the ONLY accurate type of testing other than a frequency analyzer that gives a true accurate reading.
Some think you and force an arrow to roll to the proper indexing location by compressing it in a bow press. This is not correct because it will give way to the natural bend or can give way to the weak side.
As well as any tester that relies on forcing the arrow to bend and roll it will have a high rate of success but will from time to time roll to the weak side.

On a side note the neutral plane and weak side of a shaft are not the same

I don't know a thing about this yet and it seems overwhelming to me right now. Thanks for the info. I'm going to take a look at that RAM tester and go from there. At least if I don't ever get into testing my own I'll always have you down there in Florida to do it for me. I like your arrows, it takes all the guess work out of it for me and I know when I have your arrow locked onto the rail it's the best an arrow can get.

smong2000

· #13 · Nov 30, 2019

Tapp-Nation said:
Actually if you look at indexing from a physics point of view you could put the cock vane on the static stiff side or 180 degrees away.

When an arrow is in flight and dynamic spine is presenting an arrow has only two deflections. the stiff plane deflection 180 degrees through the arrow and the neutral plane 180 degrees through the arrow.

To take it a step further if we were to test an arrow dynamically we find 45 degrees to the left and right on both sides of the stiff plane it has the exact same frequency. Likewise if we were to test the neutral plane 45 degrees to the left and right on both sides of the arrow we will find the same frequency

Am I understanding this correctly... there is a 90 degrees range that gives same occillation so 'missing' the exact location of the stiff plane by up to 90 degrees will give you a perfect 'spine match' practically speaking? If this is correct then just random fletching the shafts would give you a 25% chance of getting it right? Four arrows out of every dozen good, eight not so good?

Thinking about my Excalibur factory 16" and 18" arrows with flat nocks and all 3 vanes the same color... I have some work to do shooting each arrow 3 times to see if there is a sweet spot.

Wapster

· #14 · Nov 30, 2019

smong2000 said:
Am I understanding this correctly... there is a 90 degrees range that gives same occillation so 'missing' the exact location of the stiff plane by up to 90 degrees will give you a perfect 'spine match' practically speaking? If this is correct then just random fletching the shafts would give you a 25% chance of getting it right? Four arrows out of every dozen good, eight not so good?

Thinking about my Excalibur factory 16" and 18" arrows with flat nocks and all 3 vanes the same color... I have some work to do shooting each arrow 3 times to see if there is a sweet spot.

But work well worthy of your time....

tpcollins

· #15 · Nov 30, 2019

Tapp-Nation said:
Find the static stiff side, mark it and then rotate the arrow 90 degree.

Remove the weight, zero the dial gauge then hang the weight back on the arrow and take the spine deflection reading at that point only.

So based on your diagram from awhile back, you’re measuring the deflection of the Neutral Plane?

Diagram Text Circle Line Parallel

See less See more

wywindsor

· #16 · Nov 30, 2019

The easy way is to float them in a tub. Mark the high side. Turn your nock so that it is 180 degree's off the mark. Now you can bare shaft test your arrows. Start at a comfortable distance. One you can shoot the same arrow hole. The further the better. Shoot every arrow you intend to use. Find the one's that will shoot this tight and set them aside. The others you can rotate the nock 45 degree;s and fire again. The arrow should hit the same hole at some point. If not set that arrow aside. Find the best of the bunch and fletch them. Test all arrows again.

You can do all the test you want, but nothing beats shooting the arrow from the bow. You may need to change tip weight, vanes and so on for best accuracy.

Reactions: 1

Tapp-Nation

· #17 · Nov 30, 2019

smong2000 said:
Am I understanding this correctly... there is a 90 degrees range that gives same occillation so 'missing' the exact location of the stiff plane by up to 90 degrees will give you a perfect 'spine match' practically speaking? If this is correct then just random fletching the shafts would give you a 25% chance of getting it right? Four arrows out of every dozen good, eight not so good?

Thinking about my Excalibur factory 16" and 18" arrows with flat nocks and all 3 vanes the same color... I have some work to do shooting each arrow 3 times to see if there is a sweet spot.

Even though there is 90 degrees R&L of center at dynamic spine level during flight the flex finds zero

Check out flat line oscillation on youtube

1271

· #18 · Nov 30, 2019

wywindsor said:
The easy way is to float them in a tub. Mark the high side. Turn your nock so that it is 180 degree's off the mark. Now you can bare shaft test your arrows. Start at a comfortable distance. One you can shoot the same arrow hole. The further the better. Shoot every arrow you intend to use. Find the one's that will shoot this tight and set them aside. The others you can rotate the nock 45 degree;s and fire again. The arrow should hit the same hole at some point. If not set that arrow aside. Find the best of the bunch and fletch them. Test all arrows again.

You can do all the test you want, but nothing beats shooting the arrow from the bow. You may need to change tip weight, vanes and so on for best accuracy.

That may be a good way for vertical bows but not for crossbows. Spine indexing the arrows is the best! All your arrows shoot hit the same hole or close to it. Not only that, crossbow arrows are a much stiffer arrows vs a vertical bow arrow!

Sent from my iPhone X using Tapatalk

Reactions: 1

Tapp-Nation

· #19 · Nov 30, 2019

tpcollins said:
So based on your diagram from awhile back, you’re measuring the deflection of the Neutral Plane?

View attachment 160170

For spine deflection matching yes

Tapp-Nation

· #20 · Nov 30, 2019

wywindsor said:
The easy way is to float them in a tub. Mark the high side. Turn your nock so that it is 180 degree's off the mark. Now you can bare shaft test your arrows. Start at a comfortable distance. One you can shoot the same arrow hole. The further the better. Shoot every arrow you intend to use. Find the one's that will shoot this tight and set them aside. The others you can rotate the nock 45 degree;s and fire again. The arrow should hit the same hole at some point. If not set that arrow aside. Find the best of the bunch and fletch them. Test all arrows again.

You can do all the test you want, but nothing beats shooting the arrow from the bow. You may need to change tip weight, vanes and so on for best accuracy.

If I were going to nock tune arrows I would never float them, way too many things can influence the test

I would simply got to the range shoot a group the pull out the tight arrows and start nock tuning the rest. I would rotate the nocks only about 10 degrees at a time

Once I had a set I would shoot them all at 60 yards at different spots

If needed I would twist nocks on any that were over an inch out to attempt to bring them in

Reactions: 2

1 - 20 of 140 Posts

This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.