Hello gang,

I found last Sunday that are is quite a spine variation in the same carbon shafts. We put a buch GT Entrada Ultralight .600 in a digital spine tester and the values varied between 47 and 52 lbs.

Now I heard on some other fora, that this may be caused by the seam in the shaft. This is the place where the carbon overlaps.

Anybody nows more about this and how to put the arrow in the spine tester, regarding to the seam? Same question for cockfeather.

Thanks!

I fletch my arrows so the stiff spot in the shaft is running up and down the string, so when the arrow goes thru paradox it doesn't have to fight the spine.

I don't have a tester.  Is there a way to find it without one?  Maybe paper tune to see?

The stiff spot in a shaft can be found by simply laying one across your knee, applying a little pressure with a hand on each end (flexing it), and rolling it back and forth. You can feel the difference as it bumps up and down. Easier felt on lighter spined shafts such as 35/55 and .500.
Also easier to find on full length shafts.

I've noticed it shooting through paper with my Beman Classic 500's.  They are 30" BOP with 100gr. inserts and 200gr. points.  Shooting them out of a 48# Whisperstik Voodoo they were showing way stiff until my 4th arrow showed perfect.  I started messing with them a little more and got a couple more to shoot well.  I'm gonna mess with them and see if I can get them all figured out.

I have some Grizzly Sticks that vary in spine from 59#s to 92#s in the same dozen shafts.

Float the arrows and the heavy side will always be down.

Bowmania

So I assume you want the heavy side or seam up or down with the arrow on the bow so the stiff area is in the neutral line when bending side to side.   Is there a desire to have it top or bottom?

Perhaps we should be demanding better quality control for something that costs as much as they do, eh?    

The only way to tell how good/bad they are is with a spine meter.  Frankly, I don't want shafts that aren't concentric, and I'm sure there are good quality ones out there.
If they aren't right, they should be returned to the company, and one should ask for an explanation.  

Someone started a thread about this some time ago.  It would be a good thing to post results of spine testing around the complete circumference of the shafts.  It will never get fixed until someone makes light of it.

I heard that with Grizzly sticks finding the stiff side.47-52# is not a big difference,I think it comes from the quality of the shafts.I have some GT Entrada 600 they fly just fine but they are the least expensive GT's.I mean the GT Entrada has a .006 straightness,Ultralight's have .003 and Ultralight Pro has a .001 for straightness.And the Pro's cost twice as much as the Entrada's.I feel it comes down to how much are you willing to pay for in the quality of the shaft,I have some CE Maxima that are very consistent but they were $110 for a dozen.

I had some Gt that were not consistent in spine within the same lot,I quit using them.Now I shoot Carbon Express and I find they are more consinstent in spine.

With wood arrows, the shaft's stiffest spine is oriented perpendicular to the bow side plate.  I would assume you would want to do it the same way with carbons, though two posts above suggest otherwise.  That's a problem for you carbon  shooters to figure out.  I shoot woodies.    

Orion, that's a good point when dealing with a solid material, but hollow shafts of wound material do not allow for one to visually align the grain stack *^).  So one should expect concentricity.

JRY309,  The cheapest aluminum 2016, will be as uniform as the most expensive 2016.  It may bend easier, but it is still quality for the money, and one shouldn't have to pay extra for that. The extra money comes in camo coatings, more material, or extra wrappings in carbon. One should always expect quality of design from cheapest to most expensive, as far as spine, roundness, etc. goes.

While Kevin (Cupcake) was making his "Spine-O-Meter", we tested alot of different carbon shafts. We found that if you checked the spine at the fletching points, you would get different readings. We foung alot of GoldTip and Axis shafts that were way off the stated spine (GT 35/55 .500 spine) it mesured .450 and Axis .400 spine that was .360.  The difference we found at each fletch was, 55/75  (.400 spine) cock feather .415, first hen .405, and 2nd hen .407.

But in the end we found that even though some were off by .020 they still flew great. I'm not sure how much spine difference it would take to Really make a difference....

 I feel the same as most when it comes to "Getting what I paid for"  I think if I ordered .400 spine I should get .400 spine.

I'm pretty sure the GT 3555 is intended to be a 430 spine. The older ones made in Utah were 480 for some reason. They might have changed the modulus of the carbon after they made the move. Just a wild guess though.

I am not sure if or how this relates to arrow shafts; however, about twelve years ago I use to piddle around in a golf club repair shop, and one thing a quickly learned was all shafts had a stiff edge. Didn't matter if they were steel, graphite, carbon, or whatever. We had a home made rig that was basically held two small bearings about eighteen inches apart that held the shaft while you took a strip of soft leather and flexed the end of the shaft and rolled it  back and forth. The weak sides of the shaft were located, marked, and installed so they were ninety degress to the club head. This allows for a constant flex without interference from the stiff edge, or what we called the spine.

Fred Eichler on arrows.

http://www.gearfrenzy.com/pros/Fred-Eichler/?vidId=106

 

When fiberglass came on the market, the same thing was noticed.  We would hold a bare shaft in one hand and put the other on a flat surface (table), at a 45 degree angle, then roll the shaft with one hand while holding the upper end with the other. Find the spine or stiffest side and mark it with a pencil or marker. Align the index for the nock and cock feather with the high spot, that way the stiffest part is always perpendicular to the string and you will get the best flight.

Thanks Hud, I knew there had to be a simple reason I have been shooting poorly all this time...had my shafts rotated in the wrong direction. Guess I should have asked.

With carbon is the seam up or down when you identify the stiffest side?  Does carbon react stiffest in compression or tension?

Does it matter if the stiff side is perpendicular or parallel with the string as long as all the arrows are the same?