Plz help Carbon Gurus

[ChrisM]

To make this short I need help understanding how to test the spine of carbons.  I believe that I have some miss marked shafts.  I have an Ace spine tester.  The kind that mounts to the wall.  When I test these shafts that are marked 400'S they come out to just a little bit stiffer than .300 deflection.  Is this correct or will my tester not give me a true reading on carbons like the vendor told me?

They could be that stiff. I test mine on a RAM spine tester that is made for carbon shafts. It is set up at 28" with a 1.94# weight. I shoot Gold Tip shafts, 55/75 (which are marked .400 on the shaft). I have tested upwards of 30dz of these shafts and NEVER ONCE had a shaft spine out at .400. The are all stiffer, with most being between .350 and .380. There are also oddballs that are as stiff as .310, and as weak as about .390.

That's all I can tell you about it. I don't know why it is that way. You would think they would be a bit closer to what they are marked, or would be marked a bit closer to what they actually are?

Bisch

[Orion]

Manufacturers spine carbon shafts at 28 inches with a 1.94# weight, as Bisch notes.  If you're using the ACE wall mount, it probably tests them at (the equivalent of) 26 inches with a 2# weight, which yields a considerably higher (i.e., stiffer) spine reading.

[WESTBROOK]

Orion is correct...

I use the same spine tester..a 400 should be about 77-78# on that tester. If you have a 2117 handy they are a 407 spine and will give you a good comparison.

[damascusdave]

The way I see it is that carbon shafts are a compound bow thing that we get involved with...the fact is the way compound bows are shot today spine is pretty close to irrelevant so manufacturers feel no need to have close tolerances...so called traditional carbon shafts are just regular carbons with a paint job so no wonder they are no better...I shoot Easton shafts because I believe their quality control is better yet in talking with a FITA shooter a while ago he told me he only gets 8 or 9 arrows out of a dozen X10's that meet his specs...take a look at the price of a dozen of those puppies if you want some sticker shock

DDave

[Zbone]

"he only gets 8 or 9 arrows out of a dozen X10's that meet his specs"

WOW, can not comprehend... Figured Olympic shafts would be MUCH more precise than that. For their price, personally would send every one back (enclosed with a little note) not within tolerances...

With Easton's reputation, figured they'd have better quality for their top of the line shaft... Hmmm, makes me wonder...

[M60gunner]

Dave is right on about spine not mattering with wheel bows. The guys I know that shoot carbons with wheel bow seem to care more about weight of arrow, lighter the better.

[Zbone]

Yeah but... Those high end, high dollar, Easton X10's are shot in FITA (Olympic events) which are recurves...

Can't imagine paying that kind of money and the spine being different... With that kind of money you'd think they'd be between a pound or most two... Their aluminum XX75s are, or I should say used to be...

[Tedd]

You are correct about the ACE wall hang spine tester. It won't even be close to the factory reading. The ACE wall tester is good for finding matched shafts. But the read-out doesn't correspond with anything. I really can't imagine why ACE wouldn't have kept with the standardized read-out when designing that product. And it doesn't tell you in the description that it doesn't match the standard read-out. I have had mine for years and just tolerate it because a good one costs so much.
I think that sounds right like Westbrook said. I never look at the decimal. Just the lbs spine. My .340 are around 102 spine if I remember correctly. (just checked them Saturday!)
I have found the even the Gold Tip XT shafts have a very slight but consistent weak/strong side. About 2 lbs. How that stiff side is oriented when shot make a big difference in flight!!!
I can shoot the same bare shaft turned one way is fully nock left weak, If I rotate the shaft 1/2 turn it is nock right stiff.
So I orient all nocks the same in reference to the stiff side of the shaft.
I sure would like to have a precision full sized spine tester.

[WESTBROOK]

The Ace wall hanger corresponds just fine to AMO spine measurements (2# on 26" spread)wich is what wood shafts have been measured with for years.

Take any aluminum or carbon deflection, Stu's calculator has a converter that will tell you what it should read in #AMO.
2216=.376 >84#
2117=.407 >77.5#
2020=.426 >74#
2018=.464 >68#
2016=.531 >59.4#

My Ace reads within a 1/2# of what the numbers say it should.

[Tedd]

Mine never matched what wood shaft suppliers send.
I kept a bunch of shafts from Rouge River that they had marked the spine on. a 90lb RR shaft is about 80 on my Ace.

Tedd

[WESTBROOK]

Yup...that's why I keep that collection of aluminums around..for verification. I know what they're supposed to read and when I get a screwy bunch of shafts I have something to double check with. Just cause mine reads different from theirs don't mean mine is wrong.

I got a dozen 65-70# shafts from one of our most "prized" suppliers that spined from 58-70# and not just a couple were outa wack.