How much variation in spine is OK?

[Gdpolk]

I'm spine testing and orienting all of my arrows as I rebuild them. What variation in spine weight is a good tolerance to shoot for?  My plan was to save my best shaft for bareshaft testing, build my next best shafts as brodhead shadts, my next best ones as small game hunting arrows, the rest as stumping and target arrows. My least consistent shaft will be getting a flu flu fletch as that'll be a short range only arrow with LOTS of steering and the one I'm most likely to grab for the "I'm probably going to loose this" shots.

[Pat B]

The proof is in the pudding. I'm assuming you are working with wood arrows. Traditionally arrow shafts have been sold in 5# spine groups. After shooting wood arrows for many years that spine spread is very usable...but the proof is in the pudding. See how they shoot as finished arrows. That is where it counts. I usually take my top 3 best shooters and put them in my hunting quiver. Each wood arrow shoots differently and a lighter spined arrow may shoot better than a heavier(within the 5# range) or visa versa so shoot them all as finished arrows and choose the ones that shoot better for you and your bow.

[Sam McMichael]

The amount of variation, in my mind, is irrelevant as long as the arrow flies well. Some bows will be tight on this while others handle quite a variety of spines. For example, when I first got my NM Shelton (53# at 28"), I found it shot 50- 55# up through 65 -70# with acceptable results. The high end arrows did show a bit of stiff wobble but hit point of aim just fine. However, 50 -55 and 55 - 60# shot equally well.

The only significance of this observation is that you may be surprised at what will perform. Therefore, just shoot which does a better job than the others without consideration for the numbers. Good flight and point of impact are all that counts.

In all honesty, my accuracy is more affected by how solidly I can hold the bow than by the actual physical properties of the arrows I shoot. If it "hits good" shoot it with confidence.

[ChuckC]

Just a guess, but i am thinking that the answer depends a lot on the bow and the arrows and the shooter.

How deep (or not) is the bow cut. How "fast" is the bow's response.

What diameter arrows, what material is used, how close to "optimal" is the median of the spine range.

How good are you at getting a clean amd a consistent release, as well as obtaining a consistent draw length.

[woodchucker]

What Pat B, said.....
The finished arrow is what counts! My son Tyler builds all of our arrows. The poor flyers, go in the stumping bucket. The best ones, the ones that ALWAYS shoot where you look, get Razorheads and go hunting!!!
Build them, shoot them, you'll easily find the best ones...

[Pat B]

When I got my old Treadway bow back in 1998 Mike suggested 60#-65# spined arrows for my 56#@26" draw and they shot like darts. I just had Mike reduce the weight on that same bow to 48#@26" and last weekend I shot a 3D course with the same arrows. They still shoot well even with a 8# drop in draw weight.
 I shoot mostly selfbows now and I start off with arrows that are spined at about 10# less than the draw weight and generally they shoot very well for me. Even with 30" arrows for my 26" draw I can make them work with different point weights and/or tapered shafting like hill cane and hardwood shoot arrows. I like longer arrows also because for me they get around the bow better.

Don't know diddly about wood, but if you are talking carbon, there are real good shafts with tight spine tolerances, and there are some out there that are horrible!

I used to shoot a carbon shaft that was pretty bad as far as spine tolerances go. This was a well known shaft from one of the big players in carbon shafting, and cost nearly $100/dz for just the shafts! I did not know any better. When I got my spine tester, I was amazed at how crappy the QC was with this company to sell these high dollar shafts with as much variance as there was, almost .100" in any given dozen shafts! I would buy dozens of shafts, and then spine them and sort them into .010" groups.

It really bothered me that they were as far off as they were, so I started looking at alternatives.

I now shoot Easton FMJ shafts, and every shaft from every dozen I have spine tested have all been within .010" deflection! I have seen the light when it comes to spine tolerance with carbon shafts!

Bisch

[Sirius Black]

Bisch, I've just gone to FMJ's (I shot them in the past thru "other" bows, and really liked them). Good to hear that Easton's spine tolerance is respectable. I shoot them from my new Kodiak, and they are great! I did substitute the stock 16gr inserts for the heavier brass ones. Even with the added cost, I may get these arrows for all my bows!

[Gdpolk]

I'm shooting carbons.  Specifically, Gold Tip Traditionals.  All of my 18 shafts are within a  0.010" extreme spread of average deflection of each shaft.  That said, each individual shaft has variances of +/-0.002" - +/-0.006" with the vast majority reading out in the 0.004"-0.005" of deviation in spine.  

Of the 18, 10 average within +/- 0.001" average deflection with variances no greater than 0.005".  I am considering these 10 to be my better shafts and the ones that will be reserved for bare shaft, broad heads, and small game arrows as they will be the most consistent for the shots that matter the most.  The outliers however could be useful for general target practice and stumping where extreme tightness and consistency really isn't a requisite.

If you look at it empirically, however, the extreme spread of my weakest shaft at the weakest point vs my strongest shaft at the strongest point is a 0.021" variance in deflection under a perfect 2lb weight (I'm 1/2 of a grain heavy actually) at the recommended 26" span.  It seems like quite a lot of variance in such a small number of shafts.  I planned to take my two greatest outliers and fletch them as 6-fletch flu-flu's as those tend to be not only short range only arrows, but have a TON of extra steering, and are what I grab when shooting into thick vines/brush where I may easily loose an arrow because they are easier to spot and see.  So for such a short range, over-steered, potentially disposable arrow it kind of makes sense to use my outliers for them.

I'm just curious what kinds of batching based off spine would be considered reasonable on carbons.  When I build up my overall arrows I also tend to weigh each completed shaft and each point that I use and pair them up so my heaviest heads go on the lightest shafts and visa versa in an attempt to get the overall arrow weights as consistent as possible.  Again, it's probably a bit anal but there is an academic pursuit/pleasure that comes from knowing that you've done literally everything that you can to ensure that all of your gear is the best it can be for entering the field and that IF things go wrong it's all because of the man behind the bow and NOT because equipment failed or was improperly selected or tuned.

IMHO, if you are within .010" deflection, you are good to go!

Bisch

[Gordon Jabben]

I made a set of eight cedar arrows that are spined from 52# to 92# in five pound increments so new archers could see which spine shot best out of their bows.  This is a picture of my first group shooting these arrows at a 13 inch NFAA target at just over 20 yards.  Although some of the arrows had a little wobble, the group is about what I would have with perfectly spined arrows. I was a surprised the spine wasn't more critical.
 

Originally posted by Gordon Jabben:
I made a set of eight cedar arrows that are spined from 52# to 92# in five pound increments so new archers could see which spine shot best out of their bows.  This is a picture of my first group shooting these arrows at a 13 inch NFAA target at just over 20 yards.  Although some of the arrows had a little wobble, the group is about what I would have with perfectly spined arrows. I was a surprised the spine wasn't more critical.
   

When you are hunting, that spine is more critical!!!! An arrow flying true will penetrate much.better than one that is not flying true!!!

Bisch

[Orion]

GD. I think you're worring too much about a miniscule differeence.  If I'm interpreting your figure correctly, and the spine charts I have,  a .02 difference in deflection translates into about 2# of spine. That's actually quite close. Very few archers could detect that difference in their shooting.

And, Gordon presents an interesting observation/experiment.  It's been my experience, too, that most bows will shoot a fairly wide range or spines accurately, and with good arrow flight. Not as wide as Gordon's experiment, but often 10-15# or more in variation, particularly if the bow is cut to center or past center.

[kenneth butler]

Gordon,  that target is a thought provoking eye opener. I never would have thought to even attempt that. I agree that a good flying arrow is certainly best for penetration. Those arrows appear to be straight in the target and to the same depth,except for the one. They grouped about as well as my capabilities. Did the flight of all of them seem good as well? It would save a lot of time slacking off on the details of each shaft. Thanks for sharing the information.>>>----> Ken

[Gdpolk]

Originally posted by Orion:
GD. I think you're worring too much about a miniscule differeence.  If I'm interpreting your figure correctly, and the spine charts I have,  a .02 difference in deflection translates into about 2# of spine. That's actually quite close. Very few archers could detect that difference in their shooting.

And, Gordon presents an interesting observation/experiment.  It's been my experience, too, that most bows will shoot a fairly wide range or spines accurately, and with good arrow flight. Not as wide as Gordon's experiment, but often 10-15# or more in variation, particularly if the bow is cut to center or past center.

I wholeheartedly agree that I am being very picky! That said if you have the time to be so and the equipment to do so, why wouldn't you be? We spend soooo much time and money chasing animals, keeping in practice, using vacation time to hunt, etc that if I can spend an extra 1-min a shaft when building them and then enter the field knowing that EVERYTHING is as perfect as humanly possible then I'm going to do so. This gives me pleasure acedemically and intellectually to build a better intimacy and understanding of my gear, allows me to optimize my gear to my needs and improve performance on game animals for the sake of being as humane a possible, and helps to instill confidence that when I relax those fingers everything will do exactly what it was made to because it was painstakingly tested and engineered to be perfect.

[Tim Finley]

does anybody really know what spine their wood arrows are ? So you spine them with the grain and say you get 55# and that's what you want so you set it aside to make your arrow , did you ever think to rotate that shaft 180 degrees and see what it spines on the other side it could be 48 or 50#s or maybe 62 #s  and that is the side that you line up with your hen feathers so your arrows may spine quite a difference. I mark mine and aline the side of the arrow with the proper spine with the sight window.

[Orion]

GD.  Whatever works for you.  I'm not chastizing.  However, what you describe as a large variance I view quite small.

"the extreme spread of my weakest shaft at the weakest point vs my strongest shaft at the strongest point is a 0.021" variance in deflection under a perfect 2lb weight (I'm 1/2 of a grain heavy actually) at the recommended 26" span. It seems like quite a lot of variance in such a small number of shafts."

Of course, whatever increases one's peace of mind and confidence on the course or in the field is a good thing.

That being said, I've been at this for about 60 years now, and given the accuracy I've seen displayed by thousands of shooters over the years, 95% of them will not experience a change in accuracy due to a 2# variance in spine among the arrows they shoot. We're just not that good.      

[Gordon Jabben]

Originally posted by kenneth butler:
Gordon,  that target is a thought provoking eye opener. I never would have thought to even attempt that. I agree that a good flying arrow is certainly best for penetration. Those arrows appear to be straight in the target and to the same depth,except for the one. They grouped about as well as my capabilities. Did the flight of all of them seem good as well? It would save a lot of time slacking off on the details of each shaft. Thanks for sharing the information.>>>----> Ken

Ken the 92# arrow was the only one that I would have noticed something out of the ordinary.  I was shooting a 55# r/d longbow of my own making. I'm sure the fairly high profile 5 inch feathers made a lot of difference.