Arrow Spine Charts

[RickBarbee]

Just an FYI:

The modern manufacturer's deflection ratings are done on the ASTM chart, and derived by checking the deflection on a 28" center with a 1.94# weight.

When spine is checked using the AMO standard (26" center with 2# weight) it will always show a higher spine than the ASTM.

EXAMPLE:
I have some shafts that ASTM spine as .300, and they are dead on.
When checking their spine on a spine tester using the AMO formula, they have a .250 deflection.

To see what the ASTM charts actually are in AMO spine, you can use the conversion formula of ASTM deflection X .825.

Example:
ASTM spine defletion of .300 X .825 = AMO spine deflection of .247

Shafts from different manufacturers, and different materials will vary some, so the conversion formula is not perfect, but it will get you close enough to make accurate shaft selections when viewing the manufacturers spine charts.

Here also is an AMO spine deflection chart.

Hope that helps some.

Rick

[RickBarbee]

I posted this in another topic, but thought it might help to have it in a stand alone topic of it's own.

Wouldn't hurt anything to make it a sticky.

Rick

[Bisch]

Arrow Spine Charts

I have not looked, but I'll bet you posted in M.E.B.'s GT thread to my response that a GT's are stiff. I have a high $$$ RAM spine tester on 28" centers with a 1.94# weight. I have run over 30dz GT shafts thru it and never once had any GT shaft not be stiffer than marked (and in almost every dz there would be at least one that was so far out it was useless). That is why I no longer shoot GT!

The fact that they are stiff made no difference to me. They tuned well, and I knew what I needed. The fact that nearly every dz had one or more that were sooooo far off that they were useless to me irked me bad, as I was paying $85/dz for just the shafts, and to this day feel GT should have better quality control!

Bisch

[RickBarbee]

I have not looked but I'll bet you posted in M.E.B.'s GT thread to my response that a GT's are stiff. I have a RAM spine tester on 28" centers with a 1.94# weight. I have run over 30dz GT shafts thru it and never once had any GT shaft not be stiffer than marked.

Bisch

Oh yeah, I agree. Most of the GT Trads will always spine higher than marked.
All of my GT Trad 7595 (.300 ASTM) actually spine closer to .290 ASTM, and around .240 AMO.

Shaft selection can get tricky & very confusing sometimes.

I just posted this for folks to have a quick reference to fall back on when needed.

Rick

[M.E.B.]

Why did they change to ASTM? I though that the archery manufactors got together years ago to set a standard so we could compare apples to apples.

My head hurts.

Makes me wish I did not sell my spine tester after I quit shooting wood arrows. I thought I was getting what I was paying for.

Oh well I have another excuse for bad shots.

[caughtandhobble]

I have not looked, but I'll bet you posted in M.E.B.'s GT thread to my response that a GT's are stiff. I have a high $$$ RAM spine tester on 28" centers with a 1.94# weight. I have run over 30dz GT shafts thru it and never once had any GT shaft not be stiffer than marked (and in almost every dz there would be at least one that was so far out it was useless). That is why I no longer shoot GT!

The fact that they are stiff made no difference to me. They tuned well, and I knew what I needed. The fact that nearly every dz had one or more that were sooooo far off that they were useless to me irked me bad, as I was paying $85/dz for just the shafts, and to this day feel GT should have better quality control!

Bisch

I always hoped you were checking on 26", lol

I have way too many GT to change now

[Bisch]

Arrow Spine Charts

Don't get me wrong. The GT's are good shafts. I have shot a gazillion critters and won a bunch of shoots with them. The issue I have with them is that they are not tightly spine matched. In fact, there are some that are so far off, it is rediculous! For what they cost, the quality control should be better, IMHO!

When I first started shooting the GT's, I did not have a spine tester. Every once in a while I would get an arrow that would fly so cockeyed that I would just have to throw it away. I had no clue why that happened. Then I got the spine tester, and my eyes were opened. I started running all my shafts thru the spine tester and grouping them in 10/1000ths of an inch groups. I would still have to throw a shaft away every now and then because instead of the normal .350-.380 range I would occasionally get a shaft in the .310-.320 range. These were all shafts marked .400spine by GT!!!! By using the spine tester with the GT's, I eliminated the "flyers" before they made it into my quiver.

I have only gone thru about 4dz of the shafts I am shooting now, and while they still show stiffer than marked, every shaft from 3 different sources has been within 10/1000ths of an inch of each other. Whatever "flyers" I have with these shafts is induced by my bad form, and not by bad QC from the manufacturer!

Bisch

[tradtiger]

It's my understanding that Warrior 400 carbons are made by Gold Tip and are the same with just a different name painted on (at about one third the price). Are they seconds? Are they actually going to have even less conformity to stated spine or Grains Per Inch than the GTs? I think they shoot well and have tuned well. Maybe my releases are inconsistent enough to cover their variances. I know those arrows sure are tough.

[RickBarbee]

I am making the switch away from GT shafts also.
It's been hard for me to do, because I have so many GT shafts, but just like Bisch I was having to go through them & cull just like I would do with wood shafts.

I am switching over to the WidowMaker shafts, and so far they are the best I have ever used. I have another dozen of them on the way, and as soon as I have them in hand I will be switching to them for good. Their only drawback is, they come from Australia, and there is only one North American dealer for them who is in Saskatchewan.

Rick

[RickBarbee]

I was just informed by a long time commercial arrow maker that:

The AMO calculation even though figured on 26" centers is to represent a 28" completed arrow.

The ASTM calculation even though figured on 28" centers is to represent a 29" completed arrow.

Good info to use along with the charts.

I never knew this.
I always just took the measurement on centers at face value,
and knowing where length changes (among other things),
so does the spine, and I just worked from there.

Rick

[speck1]

I am making the switch away from GT shafts also.
It's been hard for me to do, because I have so many GT shafts, but just like Bisch I was having to go through them & cull just like I would do with wood shafts.

I am switching over to the WidowMaker shafts, and so far they are the best I have ever used. I have another dozen of them on the way, and as soon as I have them in hand I will be switching to them for good. Their only drawback is, they come from Australia, and there is only one North American dealer for them who is in Saskatchewan.

Rick

Rick,
Where do you order the widow maker arrows from? I am shooting GT but have some axis coming this week. Trying as many as I can to see what I like. Thanks.

[Bisch]

I am making the switch away from GT shafts also.
It's been hard for me to do, because I have so many GT shafts, but just like Bisch I was having to go through them & cull just like I would do with wood shafts.

I am switching over to the WidowMaker shafts, and so far they are the best I have ever used. I have another dozen of them on the way, and as soon as I have them in hand I will be switching to them for good. Their only drawback is, they come from Australia, and there is only one North American dealer for them who is in Saskatchewan.

Rick

The guy who sells those arrows is Mick Baker. He is the guide that I went red stag hunting with in Australia. He is a good guy, and runs a great guide outfit! If you want to go to Australia and hunt stag, buffalo, or boars, get in contact with Mick at Trophy Bowhunts Australia!

Bisch

[RickBarbee]

Cameron Root is the only North American dealer I know of. He is in Saskatchewan Canada.
He's on FaceBook as Cameron Root, and on the Leatherwall as Rooty if anyone wants to contact him.

Rick

[SwampRabbit]

Interesting, thanks for sharing Rick.

BTW, I shoot Carbon Express because they say "Buff Tuff" on them. It's great marketing, especially when you know a guy named "Buff" that has an uncanny ability to kill stuff with a stick bow.

And I recently bought a Bitz arrow fletcher because I know a guy named Bisch. I figure if the name has to be shortened by everybody because nobody can remember how to say or spell the whole name, they have to be equally as good!

Never would have thought a guy would have to buy a spine checker for carbon arrows... for wood, yeah... but for carbon. Bisch, did you buy it back when you shot woodies?

[Bisch]

Interesting, thanks for sharing Rick.

BTW, I shoot Carbon Express because they say "Buff Tuff" on them. It's great marketing, especially when you know a guy named "Buff" that has an uncanny ability to kill stuff with a stick bow.

And I recently bought a Bitz arrow fletcher because I know a guy named Bisch. I figure if the name has to be shortened by everybody because nobody can remember how to say or spell the whole name, they have to be equally as good!

Never would have thought a guy would have to buy a spine checker for carbon arrows... for wood, yeah... but for carbon. Bisch, did you buy it back when you shot woodies?

No, I bought it because it popped up in the classifieds at the right time. I'm sure glad I did get it though, because it has really opened my eyes about these shafts. I never would have thought in my wildest dreams that there could be so much variation! My spine tester is made for carbon arrows. It is on 28" center with a 1.94# weight.

Bisch