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RE: Checking spine degrading
 

Me too, I need to know also.
I' ve got some 2 and 3 year old carbons that are starting to make me wonder.

RE: Checking spine degrading
 

I just found a " Ace spine-spin tester" in my cabelas catalog for (gulp) $189.99!!

Is there a cheeper way???

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RE: Checking spine degrading
 

Ddubyou, thanks. I' m trying to burn it in my brain as it has also cost me dealry in the past[:' (]. The buck was standing broadside, but foreward of my position. Which put it at a quartering away stance, but not a usual one. It' s kind of hard to explain. In a nutshell I should have aimed for where I wanted my arrow to exit. Not the traditional entry mark.

I' m also hoping some others might read it and avoid my mistake. Is it easy to understand? I have always hoped people didn' t hink I' m aiming for the poop shoot!!:D

RE: Checking spine degrading
 

Dave:

It makes perfect sense to me. I will try to make it part of the routine.;)

How are things going with the Bowtech?

RE: Checking spine degrading
 

No one has come up with a reliable, repeatable way to actually measure spine- but it' s a myth that it goes away. Take good care of your arrows, and you' ll never need to worry about it.

RE: Checking spine degrading
 

Ddubyou

Why don' t you just take them in to a pro-shop and have them tested. Most good shops should have a spine tester, especially if they also deal in traditional gear. Might be a small fee involved.

Thats not true at all. Any of it. Repeated use will effect spine. Take a piece of sheet metal and bend it back and forth a few times, will the metal weaken - of course. Same idea with arrows.

RE: Checking spine degrading
 

Trial by fire. Number your arrows, and if you find one or more repeatedly not grouping with the others, chances are good the spine is the problem assuming all other variables are equal (finished length, fletch, point, weight, etc...)

RE: Checking spine degrading
 

JoePA, My bowtec is still being a pain in my butt. I spent over 4 hours total yesterday trying to get it right again. I' ve let it sit for a week or so until my new arrows came in. (28.75" beman ics hunter 340' s
When they did I weighed each one, wrote down the measurement and then weighed each F/p and then matched any odd ball to each other.
When I went to shoot I was doing pretty good and even ruined one with a failed robinhood attempt (split the nock and shattered the end of the arrow). But then I noticed some arrows were flying goofy. Turns out they are whacking the lower mount of the Whisker Bisquit deluxe . ERRRRRGGG. Fletching contact on a WB!!!.
I was having to turn my arrows in order to avoid fletching contact with the cable.
It Looks like the ALPINE SLIDE GLIDE has stretched allowing for more cable issues than the stock cable slide. So I took it off and put the stock one back on. Still no good.
I raised my nocking point and moved the rest out and back trying to get bullets, but it just wasn' t going to happen. I even put the shakey hunter back on, but forgot about all the nock point moving around and could only achieve down tears.
So I put the WB back on and raised my nock point until I was blue in the face and then the sun went down and I went in. I left with a slightly outside the fletching 4 o' clock tear.
Tuning has never been this hard for me. Especially with a WB. My early assumption was the new holding bar was too big compared to the flat bottom one. Then I played with an arrow and realized true flight could be achieved through it without hitting anything.

Just for grins I pulled out my z-light and violla, bullet. Stepped back to 20 and plugged a good one.

There it is-Thanks for asking, I needed to vent.

I' m either just one slight move away from gettting close, or I' m way off on something.

My cam timing marks are perfect and I' m putting extra care into each shot not to torque the bow. but hard inside fletching contact keeps pushing the point to the right. I just dont know anymore...............

RE: Checking spine degrading
 

BobCo19-65- if repeated use is such a problem with graphite arrows, how is it that fishing rods can be flexed millions of times and still function perfectly?

And spine testers don' t really " test" the spine- they just find it and see if it' s unusually severe...

RE: Checking spine degrading
 

Sorry, I have no idea what you are talking about. Maybe you could explain this a little.


Spine is basically a measure of the stiffness of an arrow shaft. It measures the deflection a shaft when a two pound weight is suspended from the middle of the shaft when the shaft is supported at two points 26 inches apart.

RE: Checking spine degrading
 

Technically, it' s not really :)

What you are describing is Flex. Spine is actually a characteristic imparted via the manufacturing process that runs the length of the shaft, where it is most resistant to flex. Think of it as a kind of back bone.

Arrow makers always say spine, but what they are really talking about is flex. Can flex be affected by spine? Absolutely. Are spine and flex the same? No.

I think the intermingling of these two distinct terms is what is causing the confusion in the two threads going on about spine now...

RE: Checking spine degrading
 

Yep! Took me a spell, but that' s about what I' ve figured out too. Differences in terminology.

My spine (flex) tester is a couple of 1X6' s. One as a back and the other as a base, with 1X2' s mounted upright, 26" apart, with ' V' notches cut in the ends to hold the arrow shaft. I' ve got an arm made from flat steel loosely bolted to the back with a large bolt at the other end of the arm holding enough washers to make up 2 pounds of weight. The length of the arm is such that the weight will fall in the center of the shaft when it' s on the supports. A 1" travel indicator that measures to .001" is mounted to the base directly under the wieght and centered with the arrow shaft.

I don' t have it all worked out to where it will give exact spine, but it does great for checking variances between one shaft and another. Or variances around the same shaft.

Actually, at 26" between centers, mine is set up for wood arrows. For carbon arrows the supports should be 28" apart.

RE: Checking spine degrading
 

Oh, we are being technical. (Kidding) :D:D.


Isn' t what you are describing " flex" and what I am describing, the same as static spine???? If not, please explain. I am in no means an expert on this.

RE: Checking spine degrading
 

Aaaaahhhhh.... You are right, we are talking about two different things completely. My mistake. That' s interesting...

So when you measure " spine" as you call it, do you rotate the arrow 360 degrees while under load and use the stiffest axis as a measure, or ??

RE: Checking spine degrading
 

Neither am I... :)

I' m pretty certain static spine refers to the spine in an arrow at rest with no outside influence exerted upon it.

Take golf shafts for instance. Finding the ideal Flex for one' s individual swing is paramount to good repeatable performance. However, spine aligning is the popular rage right now as current technology doesn' t quite allow one to build a shaft without a spine. So, builders align the club head and grip along the " spine" , so it influences flex the same way club to club, hopefully. From there, they vary the flex of the shaft to meet one' s swing speed and dynamic loading of the shaft. Some manufacturers are very close to producing a spineless shaft (like Apache), where the shaft will flex identically no matter how it' s held, but the majority don' t/can' t, apparently.

This get' s into what Arthur was saying, he aligns his cock feathers along the spine, to have the best potential for repeated flex from arrow to arrow within a batch. As long as the shafts flex identically, he should be good to go. If they don' t, he' ll get fliers. Matching flex, particularly if using a fixed rest, is tantamount to tight grouping.

After all of this, I' m pretty certain everyone is right :) Spine doesn' t move or degrade, but arrow flex changes due to extended use or repeated heavy impact, causing fliers and bad arrows.

RE: Checking spine degrading
 

excert of articale on static spine

[quote][Try bending a sheet of paper - it' s easy. Roll the paper into a tube and try bending it again - it' s a lot harder. How easy it is to bend a sheet of paper or an arrow shaft depends on its stiffness. The accepted (Easton derived) standard for the stiffness of an arrow shaft is its static spine. The shaft is supported at two points a specified distance apart and a specified weight hung at the mid point. The amount the mid point of the shaft drops from the horizontal determines the shaft spine. The lower the stiffness of the shaft the more it sags and the larger the measured deflection. Given the support spacing and the weight hung the static spine depends on the elasticity of the shaft material(s) and the materials' geometries.
/quote]


Here is the article.

http://homepage.ntlworld.com/joetapley/spine.htm

RE: Checking spine degrading
 

But see, they are still measuring ' flex.' Aluminum arrows don' t really have much of a ' spine' because they flex pretty much the same no matter where you rotate the shaft to check the flex. On woods and carbons, there are pretty hefty differences from one point around the shaft to the next. Where the stiffest line running lengthwise along the shaft is, that' s the actual spine of the shaft.

Our use of the term ' spine' to describe ' flex' is a holdover from wood arrow days. The spine of a wood arrow runs with the grain and that is where you test the flex. We archers just came to call it spine. Incorrectly, I might add.

RE: Checking spine degrading
 

Patapsco. Yes, that' s exactly what I do since I learned that carbons have such a wide variance in flex, especially when you get off the actual spine.

RE: Checking spine degrading
 

Bob, in your quote, when you roll up the piece of paper, where the two edges overlap is the spine. It makes sense that it is more difficult to flex the paper with the overlap/spine on top, as it is thicker so it should be more resistant to flexing. Same theory applies to arrow shafts, golf shafts, fishing poles...

RE: Checking spine degrading
 

That clears up a lot for me.

So the deflection or flex of an arrow that we measure with the two pound weights is just that, a measurement. But the spine is the stiffest point of deflection running lengthwise on the shaft when rotating the shaft 360 degrees. What the easton chart measures is deflection then correct, and finding the correct spine on an aluminum is not that necessary because the shaft is so uniform.

I have always understood the whole concept of matching spines on cedar arrows, but the language seems very interchangable these days.

Rangeball, thanks I understand what you are saying.

But then, one question, wouldn' t a spine tester (maybe named wrong, should be deflection tester) actually help in determining where the spine is, especially on a cedar arrow?

RE: Checking spine degrading
 

Sure, a spine tester will identify where the spine is located, as well as the deflection/flex of your arrow. Two jobs for the price of one :)