# spine



## N7709K (Dec 17, 2008)

Weak won't show up at 30yds- 40yds if might depending on shooter. 50m, 70m, 90m is where all that shows up and where setups really get tested(there is a reason why I shoot my indoor arrows to 50m...). 

Stiffer shoots tighter groups with misses being farther out, weak shoots a bit more open group but misses are close to center... Again depending on shooter this will show up or not. You can tune to shoot weak, you can tune to shoot stiff and each has a place depending upon the game at hand and the skillset of the archer.


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## SonnyThomas (Sep 10, 2006)

Well, that wasn't where I was going. ... Back to "Am I under spined? Am I over spined?" I really believe you have to be out on the outer fringes of spine before spine is the real cause of poor accuracy. I think, like in think, the cause of concern is with the shooter and/or bow tune, not the spine of the arrow. My accuracy with the CXL Pro 150s could be dismissed (read again), but Danny Evans can't be dismissed with the CXL Pro 150 being wet spaghetti and at the time getting into the ASA top 10 and I believe a 3rd in ASA and a win in IBO.

Arrow charts. Some are poorly made up, but can be figured out. Easton seems to have the better arrows charts. Carbon Express has improved over the years and now reflects more of what I used for spine. Always before my arrows were deemed weak of spine - always one spine level too weak - 350s when I used 250s and 250s when I used 150s.

Robert Ragsdale. Seems he hypes on spine more than any magazine article writer, but never gets into how to arrive at proper spine. Part of my dislike of Ragsdale's ramblings...


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## N7709K (Dec 17, 2008)

But you are only looking at the static ratings not the dynamic spine the bow takes and shoots well. Regardless of what you are going off of to figure stuff or weak- short range doesn't show enough for 99.9% of shooters...


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## bigHUN (Feb 5, 2006)

I had a DST-40 last year and I was shooting #57.8 with 3 different spines from the same bow, these were my competition arrows:
CX nano XR450's for Field competition scoring, 100g SS points, helical, I had a sight tape on left side of the sight; 
CX nano XR410's for practice only for both Field and FITA, 120g SS points, helical, I had a second sight tape on the other side of the same sight; 
CX nano pro400's for FITA competition scoring, 120 TS points, helical, I was writing down my 30-50-70-90 distances...
all these arrows were put together with most attention, group tuned with a hootershooter, I made a higher FOC and the most precise steering.

This year I have a DST-38 and shooting the same arrows from last year, but....I had to cut down the carbon 1.8" from each spine.
The CX nano XR450 is 26" carbon length right now and is greatly underspined for the Absolute powerstroke, I am still shooting it for Field competition....
The CX nano XR410 is 27.25" carbon length and to get into optimum level I shall cut down about 1.5" from carbon length, I don't want to do that...
The CX nano pro 400's are 27.7" and definitely too expensive cutting them down but they still on the weaker side as well...
My true DL is 27.2" and I can go with shorter carbon lengths because I have a 4" over draw rest (Beiter), right now in the middle of the slot and the 450's point is halfway in the riser shelf opening

All these 3 spines are week for my Absolute setup, I cut the lengths about 1.8" and still need about 1.25-1.5" shorter, but ....all still grouping right now in a 10 ring at 50 meters, without me to touch anything on the rest or sight [email protected] #56/24 lbss
So, stiff or week depend of the bow .....you folks with cable guards are far away from the safe side to play like this


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## SonnyThomas (Sep 10, 2006)

N7709K, that's just it, distance. Field and Outdoor in my area is far and few between - maybe 5 events in the state. Most all 3D is 45 yards. Hunting...depends what part of the country, but 19 yards is still the average killing distance.

FOC may play more into longer distance. Still, I've always been a little light on FOC. My CXL 250s with 11 gr insert and 75 field point grouped outstanding out to 80 yards. I forget, but seems I had about 8.17% FOC. And when I was Field shooting I was plain ticked off if I missed that 5.18" diameter bull's eye at 80 yards. Carbon Express's arrow chart showed I needed 350s. See my Albums. See the 80 yard group and the broken arrow got broke from a severe whack. There's 5 arrows in the 60 yard target. My CXL Pro 150s, weak by Carbon Express technicians, had no trouble out to 60 yards - decent 2" groups when I did what I was supposed to. My CXL Pro 150s had 7.27% FOC. My present Muddy Outdoor Virtues check 6.02% FOC.


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## ron w (Jan 5, 2013)

Sonny, R. Raggsdale's writing were made back when spine was allot more important than it is now. back when bows weren't necessarily "truly center shot". at that time, spine was that important. stiff spine sprayed all over the place and soft spine was very unpredictable. the main difference between then and now, is that soft spine hasn't really changed in character much, a soft shaft is still unpredictable and fairly dependent on the shooters' quality of execution, but the character of stiff spine has changed allot, being that the bows, now-a-days,.... are truly center shot.


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## Stash (Jun 1, 2002)

N7709K said:


> Weak won't show up at 30yds- 40yds if might depending on shooter. 50m, 70m, 90m is where all that shows up and where setups really get tested(there is a reason why I shoot my indoor arrows to 50m...).


I can never believe stuff like that. If an arrow hits the spot at 30 yards, but then you move the spot another 30 yards farther away, how does the arrow know that after 30 yards of flight it's now OK to slightly veer off?

Obviously, larger diameter, larger fletching or lower density will allor for drag and drift to affect grouping at long ranges, but not spine.


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## bigHUN (Feb 5, 2006)

Now we have to clarify something....
the next what I am going to say happened to me when I was doing group tuning with a hootershooter : 
I have noticed that from a dozen ... some arrows grouping decent well @ 70 then less on 50 and may perfect at 30...
I had numbered my shafts and create my statistics chart....my findings, with both brand new shafts and already used for a season or two...(still the brand new shafts more predictable)
- some numbers were grouping well @ 70 but may drop out at 50 or 60
- some numbers were grouping well @ 40 but drop out at 60 and 30 and so on...
- occasionally some numbers surprised me flying absolutely perfect in a whole spectrum (and most likely these will be busted first , uhm....) 
What I wanted to say is, I spine match the shafts and occasionally along the season checking them in my fixture I've built (new or already used shafts), and still not all arrow numbers at all distances were grouping consistently well....grouping I meant 1.5" group at 50 or maybe max 2" at 70 (shooting with a machine). Shooting with a machine @ 50 or 60 or 70 with no wind to effect POI, a 1" off the group means to me "out"
Some shafts liked the shorter distances some middle and some the longer distances....and all these came from a same boxed set....can't explain....
so, regardless, a same dozen may not be same perfect spine or perfect weight, we have to shoot them with that bow to see how they group...


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## Ned250 (Aug 10, 2009)

I've always gravitated towards stiffer arrows no matter what I'm shooting. I recently setup my DST absolute at 54#/29.75" DL with GT22 pros at 30" with 120gr up front. Thing shot great out to 80 and I instantly shot some field personal bests. Seemed like even the bad shots were hitting the five. 

Got the bug up my ass to tinker and tried my pro tours - 420 spine @ 28"/100gr up front. They bare shafted almost perfectly right out of the gate. One single click down on the rest was all I needed. Great, I thought. These will shoot even better! Nope. They really started to widen as the distance got to 60yds and up. I've since gone back to the 22s and love them. They've costed me a few kick outs of the X, but otherwise I'm thrilled. 

I don't know why, but I've come to realize that I shoot stiff arrows the best.


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## fanio (Feb 1, 2011)

bigHUN said:


> Now we have to clarify something....
> the next what I am going to say happened to me when I was doing group tuning with a hootershooter :
> I have noticed that from a dozen ... some arrows grouping decent well @ 70 then less on 50 and may perfect at 30...
> I had numbered my shafts and create my statistics chart....my findings, with both brand new shafts and already used for a season or two...(still the brand new shafts more predictable)
> ...


You should switch to Eastons...


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## SonnyThomas (Sep 10, 2006)

Launched projectile. Long range rifle. 100 and 200 yards, ragged hole accuracy. 1000 yards out, rotational drift, Yaw, windage correction needed, but still accurate, but group maybe 4.00" in diameter. Human factor?

I am not a great or even good spot shooter. Can't help it. But, when French tuning I shoot out to 50 and 60 yards. Say I can stay in the X ring at 20 yards, 1.57". Say I shoot groups of 1.57" to 3.00" at 50 and 60 yards. How much more would 20 yards open grouping? The human factor applies. How much does the human factor effect down range grouping? Or maybe go another way....

I don't run the Circles of Field and long range shooters and never did when I did shoot Field. I took what I read and went from there. What is accuracy at 80 yards? Take in consideration when I did shoot Field I was ticked off is I missed that 5.18" bull's eye and I seldom missed. 70, 80 yards I owned that bull's eye the vast majority of times. Said somewhere between 10 to 15% FOC is ideal. I can't remember any of my competition arrows reaching 10% FOC. 

Archer's paradox is much nullified with today's compound bows. Flex up and down is more likely. Flexing or even slight paradox is gone X number of yards down range. Arrow's worst behavior noted before 10 to 12 yards. Stabilization noted at around 15 yards. Arrow is good (.001 to .0025" straightness). FOC is good. Vanes good. What offsets grouping farther down range?

Pearson MarXman bow used. Pictures mixed, but a first time French tuning, Sun glare bare shaft tuning attempt, a return to French tuning. Center low group, 55 yards - then moved to 50 yards.
Muddy Outdoors Virtue HT3, 400 spine arrow, .001" straightness, 80 gr glue-in point, 6.02% FOC, Bohning X vane 1 3/4" Shield cut, 322 grs complete. Velocity; 284.5 fps.
Pearson Legend cams a bit more aggressive than Martin Nitro Cams and Hoyt Cam & 1/2. All bows rated in the realm of 315 to 320 fps, but the Pearson giving 13 to 15 fps faster pound for pound, draw length for draw length - All bows same accuracy, I've owned all three. Effect on spine?


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## N7709K (Dec 17, 2008)

If you are borderline weak it won't show under 50m or even 70m. Shoot 30m scores with weak and ideal/stiff then shoot 70m with both... It's not a flight issue- it's a spine issue. Flight shows up in short range spine does not.


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## bigHUN (Feb 5, 2006)

fanio said:


> You should switch to Eastons...


I was thinking about that 2-3 years ago when I was looking for a jump from XR to pro shafts but I was already deep inside CX with full drawer of arrow parts...
Then again, I have dozens guys at my club they were shooting the X-10s but complaining for those arrows over sensitive as well...
btw just to let you know you may not want to shoot Field with X-10's and right beside there is no diameter close to replace ..... second, what was that again if the X-10 looses the nock goes the pin inserts as well? I don't know just remember some talking there is no collar on the shaft?....
so why would you prefer E over CX?
I know for a fact that you buy a brand new dozen from each brand and when you finally dress them up for group tuning the aftermath will show you don't have a dozen anymore....and that is a big expense and very sad we can talk about both brands.
I can't really draw a line between these two brands not in price and not in overall quality.... same story as with high end DSLR cameras one would prefer Nikon the other Canon and the rest of brands are just following....


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## SonnyThomas (Sep 10, 2006)

Well, I won't site one brand being better than another. When I couldn't get what I wanted quick for a tournament I decided to take in I bought a inexpensive dozen of Easton 2413s, camo, XX78s. Cut the way I wanted, left factory fletchings on (huge suckers) and insert and 125 gr field point. Went to the back yard and started shooting and nock twisting until I had 10 going in the same ragged hole. More intimidated than I should have been I shot my way to a 5th place first time shooting a State sanctioned event. Got what I wanted and held on to the 2413s until just a couple years ago. so 12 years old. Could spread of years I got more than half my cost back. Tried the logs once, 2712s. Shot great though less than impressed with having scroll down the grid scale quite a ways. Victory HV22s, 350s, X Killers, and a couple brands that didn't take off plus all others I've mentioned did what they were supposed to do, find the mark. 

My bottom line; Those who ask about their spine need to ask themselves instead of come on AT. About like vanes, you'll have 15 brands and models thrown at you. If one thing has gotten out of hand over the years, it's Carbon Express. CE has so many different models you don't know what to pick. And I swear CE throws a "paint" job and a new name on probably the same arrow and people say they are the best CE ever put out. I saw what was going on when CE came out with the Maxima. The old CX300s went on sale at this shop and I went home with a enough I'll never want for hunting arrows....Then, working at this archery shop I got to try the Maximas. Accuracy was not one bit better and the 250s and 350s well exceeded the CX200s and 300s for weight. I couldn't get a Maxima 250 down to the weight of the old CX300.


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## bigHUN (Feb 5, 2006)

SonnyThomas said:


> ...If one thing has gotten out of hand over the years, it's Carbon Express.....


I know for some dirty affairs CX did silently, I don't like the way how or why they did it, I would switch over to other brand but I sunk deeper then I could just turn around, too much money in parts....and 
also not sure if the other brand would be more honest...


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## bigHUN (Feb 5, 2006)

*stiff vs weak ?*

I am getting more pms with these questions about a spine, Im not going to force anybody to dive into science,
I believe a reasonably weak or stiff shaft will fly just great, regardless of the flex amount but the recovery time is important,
and that is why we put a most best steering on them....a 1.5 degree helical works for me best with a 2" AAE Max
I can't do broadhead tuning, just no such a thing for CX nano's (and maybe for x-10's as well) also I like that expression read it somewhere "paper is for wiping" especially if you doit wrong ....
CX teach me if I really want to read some signs from paper then the distance for the 400 spine family is 6 meters (oscillation? per distance? that must be a peak for the 450's to 400's) 
So what we do or how we doit? Me doing frenchtune 5 and 50 meters.
But, for the best arrow flight there MUST be some "give", the arrow MUST flex some amount at leaving the string and that motion can not be straight. So I gave him a little nose dive (referring back to paper tear about max 1/2" point low @ 6 meters). Now again this nose dive I plan at my spine tuning level in the very beginning....
Also some of the folks reading the POI wrong, they shall read about grip tuning a bit and play on their own. To add here I am strongly advocating a double sided bars, at least you try in live scoring what that neutral grip means or can make a difference to you...
I remember last year, first day of the Ontario FITA Championship, pouring rain I can see my arrows creating vapor cutting through the rain, @ 70 meters the points not that so bad with the elements, at 50 started loosing my fletching, when I got down to 30 more bareshafts then fletched in my quiver....one of my best fella told me "you can doit !!!! keep going" and I finished the 30 almost clear with bareshafts.....totaling the game with 1386. Next day gusting side wind, that 720 scoring round wasn't as expected ....
So, back to OP, I like my pin aligned with rest and string, but this just me, a lot to do with spine planning.


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## Strodav (Apr 25, 2012)

So I've sat here for the last hour carefully reading and re-reading these very long posts and found some things that are interesting, but nothing I can act on as much of it is conflicting. I can only conclude that spine is still a mystery to all of us after having spent a lot of time on it and still nobody has a good way of telling whether they are optimally spined. I'm beginning to believe spine is not the major factor many of us think it is as we can tune our bows to compensate. Does anybody know what programs like Archer's Advantage, OT2 or TAP use to calculate "optimal" spine?


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## Lazarus (Sep 19, 2005)

Strodav said:


> I'm beginning to believe spine is not the major factor many of us think it is as we can tune our bows to compensate.


And I am convinced you are almost 100% correct. Almost.

If you have your bow tuned to the point that the string is striking the arrow/nock dead center and stays there throughout the power stroke, with today's (compound) bows and rests the proper "spine" is the one that shoots the best (or gives you the biggest advantage) for the venue at hand. 

Now the caveat......"spine" consistency (in carbon arrows) is the most under talked about, under rated, under researched topic in archery. I'm totally convinced of that. The average AT'r has no idea about spine consistency because it's not listed as an attribute on the "marketing" material. Most of the general public thinks that a .001 straightness arrow, (because it is straight) is a consistent arrow. Without doubt this is a fallacy.


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## SonnyThomas (Sep 10, 2006)

Strodav said:


> So I've sat here for the last hour carefully reading and re-reading these very long posts and found some things that are interesting, but nothing I can act on as much of it is conflicting. I can only conclude that spine is still a mystery to all of us after having spent a lot of time on it and still nobody has a good way of telling whether they are optimally spined. I'm beginning to believe spine is not the major factor many of us think it is as we can tune our bows to compensate. Does anybody know what programs like Archer's Advantage, OT2 or TAP use to calculate "optimal" spine?


Have wondered the same thing, what calculation, formula is used. I don't know of a testing facility like firearms has, White Laboratories. White is not cheap for wanting a shell tested, $175 over 30 years ago. I was then using far heavier bullets in a .357 magnum, 200 grs. White concluded, by my information, that my round was excessive. Today, my heavy load is surpassed by quite a bit.

Note; By my old notes and then present formulas I came up with this number, 225218, never given as a constant. Okay, over 30 years ago and firearms. Example; arrow 380 grs. divided by 225218 times 270 fps times 270 fps divided by 2 = 61.49844 ft. lbs. Check for the difference using the given archery formula...

More; While looking over my notes and Pistol and Rifle loading manuals I found many things that I had forgot. Drag, angles and wind deflection. I don't know any archery book defining distance and wind and arrow error or means of compensating.

 Cross wind; Z = Vcw (t - X/Vo), but then the crosswind component of the bullet velocity Vz = Vcw (1 - Vx/Vo).
Who'd sit down and figure this out for a arrow?

Still looking over my old loading manuals. If by defining parameters (firearms - pistols) accuracy (group wise) at 100 yards would be the same as the average of 15, 20 and 25 yards. So if 1.5" at 20 yards (?) for a arrow, then 1.5" at 100 yards? Being mortal I know I couldn't do it, but then I don't know of many pistols that can shoot 1 1/2" groups at 100 yards. Best I ever did was 3.00" for 6 shots. Milk jugs used to be almost a piece of cake, but then I only cleaned the 200M (218 yards) Pistol Silhouette range once and those silhouettes are 4 and more times larger than a milk jug.


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## bigHUN (Feb 5, 2006)

Strodav said:


> ...Does anybody know what programs like Archer's Advantage, OT2 or TAP use to calculate "optimal" spine?


I have all of them and mostly using for printing sight tapes. With a very precise measurements the OT2 can give me decent calculation.


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## bigHUN (Feb 5, 2006)

Lazarus said:


> ...
> Now the caveat......"spine" consistency (in carbon arrows) is the most under talked about, under rated, under researched topic in archery. I'm totally convinced of that. The average AT'r has no idea about spine consistency because it's not listed as an attribute on the "marketing" material. Most of the general public thinks that a .001 straightness arrow, (because it is straight) is a consistent arrow. Without doubt this is a fallacy.


I have built a spine tester myself (manufacturing background, mechanical engineering in product development) and I measure all my new set of arrows and year around occasionally I re-measure my in-use arrows.
The carbon is changing properties along the use, heavier-rough use will move the stiffer/weaker side around probably do to damage to some internal strands how they wrap it layer by layer.
That means, we will nock turn but not only because the nocks or the inserts got bent a bit, but also because the shaft switched the stiff side....
Even the brand new set of 0.001 straightness dozen have large deviation in stiffness and side of the stiffness, some of the carbon tubes may have also two stiff sides....
I measure with a one micron dial indicator... lets call it "half thousandths of an inch" and I have found 0.005 deviations in the stiffness in a same spine numbered brand new shafts rated 0.001 straightness.
This why many long range shooters prefer higher FOC dressed with toolsteel or tungsten points.
My next investigation was towards
- shorter arrow weaker spine vs longer arrow stiffer spine....
I know for fact Olympic bow shooters prefer longer arrows, but from the compound perspective longer arrow is more vulnerable to human errors (we know for many of them)...
Me personally like shorter 450's then longer 400's from the same bow...somehow I can just group tighter with less human effort...


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