Spine Testing Carbon Shafts?

[The Singing Bowyer]

For those of you who have tinkered with carbon shafts, can you tell me if I were to put them on my spine tester like I do my woodies and get a reading, does that mean much to me? Does the number represent the high end of the spine, the middle? Any light you can shed will help me. I haven't fooled with them much before and I am trying to get a buddy's arrows to fly better with a broadhead....

[freefeet]

Not sure if this helps but i put my CX Terminator Lite Hunter 6075's on my spine tester and measured as thought they were wood and came up with 84# on all 12. For me it has more meaning than the carbon spine deflection method.

The 6075's are listed as .342 deflection but i never switched my spine meter over to carbon spine measuring so never checked that as it doesn't really mean much to me.

[Old York]

TSB, what are the metrics of your tester?

26" centres with 2# weight
or 28" centres with 1.94#?

What is your "number"?
Pounds?
Inches of deflection?

[The Singing Bowyer]

I have the Ace Spine Tester that hangs on the wall. I believe it is a 2 LBS weight. The arrows he is using are coming out at 70 lbs across the board, with a deflection of .380.

They are a tapered carbon, and according to the directions that came with the tester, I am centering the arrow at the midpoint on the shaft.

These arrows are rated for 45-60, so I wanted to see what others have found with checking carbon shafts, and if it is normal for the maunufacturers to have a stiffer spine that rated.

I double checked my woodies, and all calibrations seem to be correct....

[The Singing Bowyer]

Freefeet,

What did you mean by " i never switched my spine meter over to carbon spine measuring so never checked that as it doesn't really mean much to me."

Is there a different way/method for measuring carbon?

[Old York]

Sorry, TSB, can't help you. That spine tester has it's own "system" of where the shaft is loaded and by some unknown [to me] mass. Also, tapered shafts don't rigidly follow simple beam deflection [theory].

If you compare two shafts of different materials, but with the same static spine,
you're still dealing with different oscillation  recovery rates....I.O.W.,
they have different dynamic spines. A woodie and a carbon with the same
static spine just ain't gonna fly exactly the same, all other things being equal.

[freefeet]

Originally posted by The Singing Bowyer:
Freefeet,

What did you mean by " i never switched my spine meter over to carbon spine measuring so never checked that as it doesn't really mean much to me."

Is there a different way/method for measuring carbon?

Yes.  As OY said above...

wood is measured @ 26" with 2# weight
carbon is measured @ 28" with 1.94#

Wood is measured in lbs, carbon in inch deflection.

I'm not sure if all spine testers can switch between the two or not.

I have no idea why the carbon people just didn't stick with the same system that wood uses, it would have made things so much simpler.

[The Singing Bowyer]

So why do they mark 40-60, 55-70, and so forth if they are going by deflection? Seems strange.

Also, my spine tester reads both deflection and spine at the same time.

My only question, I guess, is if I am getting a reading for spine with a carbon arrow, does that generally reflect the high reading for the dynamic spine?

In other words, is there a way of showing what the variances are in dynamic spine using a tester or not? I think his shafts may be a bit stiff, causing his grouping to be a little off. They don't seem so stiff that they are hitting at an angle, but still a bit stiffer than necessary.

[DesertDude]

If you want to talk spine testers and carbons spine, give "Cupcake" a pm.  He designed a spine tester and he and I teasted alot of different carbons and can relate our findings.  I can help if you want to caht on the phone.

Mark

760-289-2013

[Jason R. Wesbrock]

Originally posted by freefeet:
Yes.  As OY said above...

wood is measured @ 26" with 2# weight
carbon is measured @ 28" with 1.94#

Wood is measured in lbs, carbon in inch deflection.

I'm not sure if all spine testers can switch between the two or not.
 

The only spine tester I'm aware of that measures using both systems is the new Ace Spine-Spin tester.

[The Singing Bowyer]

The Ace Model 203 also does both....which is the one I am using.

[jacobsladder]

Chad ..good to see you on bud.... still enjoying your music!  Have your bud follow the tuning tips on bowmaker.net


So many variables with carbons... although tapered should allow a wider range of spines.

[freefeet]

Originally posted by The Singing Bowyer:
The Ace Model 203 also does both....which is the one I am using.

The deflection readings you're getting are still across 26inches.  Carbon deflection is measured across 28".

The spin and spine tester allows you to build the tester at either 26 or 28 inches, depending on whether you want to test carbon deflection or wood deflection.

I would ignore the 6075 numbers on carbons, i think they're more for wheelie bow users than trad shooters.  I shoot a 46# bow with 6075's.

[The Singing Bowyer]

Got ahold of some fellars last night that helped answer a few questions. Appreciate all the feedback. Loaded his arrows with some brass inserts and extra weight, and they shoot like darts...