Do arrows loose their spine that often? Would it be more prone in carbons than Aluminums? What about composit shafts such as ACCs? Are some of our fliers a result? Is there a way to test for it?

This happens to Carbon ICS type arrows much more frequently than many suspect, and in fact within a new dozen one usually finds a few of the arrows don' t spine match. Either of these scenarios or a combination thereof result in flyers and arrows that just won' t group. It is a lessor problem with pultruded carbon shafts, and non-existent in ACC and aluminum unless the arrow is bent as there is really nothing to degrade...

This is the main reason I switched to ACCs and have never looked back. Consistency from arrow to arrow, shot to shot.

Good questions.

As Rangeball noted, IC type carbons are very susceptible to this. Carbon degrades under heavy stress over time. Repeated shots into a target (especially 3D targets), soaking up all that load from the bowstring, etc. Since the IC carbons are made with various angled, perpendicular, and parallel weaves, over this time, those layers basically shift. This affects the spine of the arrows, and basically they “bend”.

In addition, since it sucha difficult process to get all these layers “right” when the arrows are initially made (because unlike aluminum, once carbon is “worked” you are stuck w/ what you get), you get some that just are not as tight as others..straightness.spine..weight..are all affected. Manufacturers have gotten around the straightness and weight issue for the most part by hand selecting and grading the cream of the crop (though many are still exaggerating straightness on their premium shafts). However, spine variations do continue to exist, even in these premium shafts, just by the nature of their construction. Though the percentage is smaller, you still can get a ew flyers out of a dozen premium carbons. I’ve spine tested most of the big brands (several dozens of each), and most people would poop their pants if they saw the variation many of the mid and low grade carbons have. It has improved in the past couple of years, but even the premium grade IC carbons are still not on the same level as Aluminum and A/C technology.

In the “old days” you used to hear fellows saying they shot their aluminums spine out. It’s entirely possible I’m sure, but I’ve never had enough aluminums last long enough to notice the phenomenon; They bend , dent, or break long before that fatigue would come to pass.

A/C technology, because it uses high grade aluminum, and parallel wraps ONLY, makes it much possible to get exacting spine, weight and straightness not only from arrow to arrow but dozen to dozen. But they take longer to make, and use a more detailed process, hence the price increase. In addition the A/C shafts are graded into much tighter weight tolerances, and given a letter code so you get the same weight arrows as you did with your last dozen (w/in +/- .5 grain for ACC’s). IC carbons, depending on grade, can vary 10 to 20 grains plus from dozen to dozen of the same spine shaft. For example: I have a two “half-dozens” of 60/75 Terminator Selects. I bought the half dozens at two different times. Though each shaft is within tolerance for their respective group, the two groups have a 19-21 grain difference in weight (avg 440 grains vs. 460 grains w/ completed shafts w/ exact same weighted components and cut lengths). Guess what? 6 of those arrows don’t group with the other 6.

The only real “disadvantage” to A/C technology is the expense. I see people say they are not nearly as durable as IC type shafts, but I’ve yet to find that to be true. I have at least 4 or 5 3-49’s right now that have from 3 to 5 nock end hits (you can see the dings on the uni-bushings) ,and they are still straight and group tight.

The real problem with A/C durability IME, seems to be from the folks who yank on them like they are a nail in 2X4 when they are pulling them out of 3D targets. Thing is, many IC carbon shooters don’t realize that putting an awful lot of wear and tear on their preferred shafts as well (internal cracking& layer shift from extreme bends) and it reduces their life greatly too.

You don’t necessarily need an ACC to kill a deer, but if pure repeatable accuracy from every shaft you buy (even among several dozens) is high on your priority (it is my highest) than A/C and XX alum technology is King.

Wow JeffB, that was like reading an artical out of a magazine. (did you cut and paste that???)

I hope people don' t think I' m lying on the other cabelas carbon arrow post, but when I got my beman ics hunter 340' s in this week I weighed each one and wrote the weight on each fletching. I ended up with seven at 338.5 grains, and the rest were between 334-337. Granted this isn' t a high end scale, just one of those archery catalog golden key (I think) sliding rule/ balance type scale.
I thought they were pretty close considering the cost.

*#&$* just typed a long response and got it zapped.

Cliff notes version- All tubes have a spine, and it never changes it' s orientation. It' s true that the graphite and epoxy matrix will degrade over time, but consider fishing rods... I have 20 year old fly rods that have been cast hundreds of thousands of times, and the spine is still in the same place and the rod is still going strong. Were the graphite to " shift" in any way, the arrow would shatter on the next shot. It' s a myth that spine goes away.

I know this from owning a fishing rod business making custom rods for the last 17 years. In the fishign industry, spine is a really big deal and well studied. Bottom line, just mark your arrows and look for flyers. Discard any flyers, and put it out of your mind. Those arrows will not go bad for thousands of shots unless they get dinged.

One thing to think about- many of the epoxies used to make arrows degrade in sunlight. Never leave your arrows or your bow in the sun any longer than it needs to be.

Fishing rods ain' t arrows. Arrows ain' t fishing rods. The stresses are totally different.

There is wear on the outside diameter of the shaft from going into and being pulled out of target materials. If you take a micrometer and measure the diameter of the first few inches of an arrow that has been shot a lot and compare that to the middle of the shaft, you' ll find a good bit of difference. I' ve got some carbons that show nearly .020" of wear.

Arrows get rapidly compressed, front to back, going into the target and stretched when being pulled out. The friction going into and coming back out of a foam target heats the shaft, and repeated heating and cooling does it' s own small bit of damage. Shooting them in full sun in extremely hot weather softens the epoxy matrix and changes their spine a bit. The epoxy gets harder and a tad brittle in extreme cold.

Compression, elongation, heat and cold cause the epoxy to break down which also changes the spine. The outside diameter wearing down changes spine. Not to mention the UV breakdown you pointed out.

I doubt you can find a single pro shooter, or even one of the better amateurs, that sticks with the same dozen arrows for an entire season of 3D. No matter what they' re made out of, ALL arrows lose spine. Some faster than others. Wood is worst. Carbon is better. Aluminum is best.

It' s not a myth. It' s a fact.

Your right that the stresses are different, but you are missing my point. The spine of an arrow is a function of a number of things, but mostly derives from slight variations in wall thickness caused by uneven distribution of the graphite/epoxy matrix. This does not and can not change. As to arrows getting different stess then fishing rods- you are certainly right. Fishing rods flex across a much wider arc- often greater than 90 degrees- which one would expect would be very hard on the spine. But it isn' t- rods get flexed more than 90 degrees on testing machines for up to a million repetitions with no loss of structural integrity. It' s not the flexing thats the problem

The wear you are measuring is no surprise, and is at the heart of why graphite arrows must be replaced after a period of time. You have the insert being forced into the arrow every time it hits a target, which can cause the shaft to expand slightly or even break at the tip. You have a little of the graphite/epoxy matrix lost in the target every time it impacts too, making it smaller. Over time, this forces you to replace your arrows.

Graphite arrows will wear out, there is no question about that- but it isn' t " spine degradation" that' s the problem- it' s wear and tear on the tip of the arrow.

How long would one of them fishin' pole blanks last if you dropped it end first off the top of a 5 story building into the parking lot? And repeated the test time after time after time? You reckon the shock of impact will make the matrix will break down a mite and reduce the spine? How about giving them a rubdown with 600 grit sandpaper between drops. Think that will eventually change the spine? How about hooking one up and using it to tow a car out of the mud? You think that will pull the matrix apart a little? That' s what I' m talking about happening to the ICS type carbons. Flexing isn' t an issue, unless they' re really torqued around to nearly breaking point.

The problem with arrows is that not every arrow is shot into exactly the same place every shot. One will hit something a little harder than the one before it. One might wind up stuck in a tree or bouncing off a rock. Say you forget to lube your arrow and it gets stuck in the target. Takes you, two other guys and a strong mule to pull it out. You might shoot one arrow out of a dozen a hundred times and another only 30. Different accumulation of shock, stress and abrasion. The one shot more will eventually beome less stiff than the other one and they' ll start shooting to slightly different places.

Being carbon, I doubt they ever shot exactly the same to begin with, but that' s beside the point, and the beginning of another.

With my homemade spine tester, I' ve found that carbons are pretty much like wood arrows. And like fishin' poles. They have a side that spines stiffer than anywhere else around the shaft. With fishin' pole blanks, you run the line guides down the stiffest section of the rod for best strength and casting accuracy, right? With carbon arrows, put the cock feather on the strongest side for best consistency and accuracy. (At least, that' s my theory and what I' ve begun doing. Seems to help.)

But the carbons I' ve checked have been very inconsistent in spine. Even when comparing the stiffest section of each shaft to each other, and that' s even when they' re new. After they' ve been shot a good while....
You see how inconsistencies can develop within a dozen arrows after being shot awhile. When they start off inconsistent in the first place, and with the fletching stuck on without any regard for the stiffest section of each shaft, any wonder why those fliers start showing up?

None of the things you mentioned will change the spine except the sandpaper. You can change the spine by lightly sanding an arrow or a fishing rod on one side only. If you sand it all around, the spine stays the same, but sand only one side, and eventually the spine will shift (to flexing more easily on the side you sanded). Believe it or not, some rod builders will sand a blank at specific places to increase the flex in the rod at that point. It was common practice with bamboo, but it can still be done with graphite or fiberglass rods. You just need to be more careful, because there isn' t much material there to begin with.

What you are saying about inconsistencies in spine between arrows makes a lot of sense. The more similar the spines are between arrows, the better the arrows are going to group. I' m not arguing that point, I' m sure you are right that they can be inconsitent. I' m only saying that spine is an inherent quality of an arrow, and that for any given arrow- once it' s made the spine itself will not change unless the arrow either loses a good amount of graphite along it' s length (on only one side), or if the arrow is severely damaged.

I' m sure you have noticed too in your measuring that most arrows (and rods) have more than one spine. Some have 4 or 5 noticable spines. When making fishing rods, you find the absolute weakest spine, and you place the guides so that when you flex the rod to cast, that natural flex axis in the rod will " steer" your lure. But lots of builders feel that this is over-rated, and that really it makes little difference. Case in point- the big rod making companies don' t even bother with spine, they just put the guides on randomly- and you never hear people complaining...

In other words they' re knowingly making an inferior product to what they could be making with a little more time. But, by making the inferior product you can get more production. You never hear anyone complaining because most people don' t have the skill to tell the difference and the ones that do have the skill and use the product are generally paid to promote that line of rods. That about got the situation covered?

There are quite a few guys here that do have the necessary shooting skill to see huge differences in arrows that most people would never notice.

And I think maybe I' m seeing what you' re saying. You' re talking about shift in spine orientation while the rest of us are talking about degradation in relative stiffness.