View Full Version : Shaft spine?
12-05-2005, 05:08 PM
I've made some custom fly-rods over the years and one of the things you want to check your blanks for is spine. For those that don't know what this is, it is that portion of the circumference of the shaft that flexes least. Clearly this is beneficial to know when building up a fly-rod.
I've had the bow shop I use build my aluminum arrows thus far. I've been thinking about rolling my own for a while now and was wondering if it possible to test for spine on aluminum and carbon arrows. If possible, I'd be willing to bet that building up an arrow with precise/consistent spine location in relation to nock, vanes, and head would improve flight consistency and thus accuracy.
Is it possible to test for shaft spine? Any arrow aficionados out there know the answer?
12-05-2005, 06:06 PM
Right you are: most man-made arrow shafts have a "spine". The same is true of golf clubs, if you've ever delved into the devil's game and built your own clubs. A TrueTemper Dynamic Gold aluminum golf club shaft has a spine that you need to find just like most arrow shafts. The "spine", or stiff side, is a result of the manufacturing process and is as predictable as rain. If you notice, most Easton aluminum shafts have a bright shiny dot near the nock end. That's there to denote the spine, or stiff plane, of the shaft. If you don't take the spine into account you may have inconsistent results.
Here's how you find the spine of an arrow shaft. Place the nock end of the shaft in your palm and put the point end of the shaft on a smooth work bench or table. Then, using the flat palm of your other hand, roll the shaft back and forth. You'll fell it "break" each time you go past the spine. I always align my golf clubs and my arrow shafts with the spine to maximize stiffness. On arrow shafts that means you have the string perpendicular to the stiff "spine" of the arrow shaft.
Your instincts are spot-on regarding carbon and aluminum arrow shafts.
12-05-2005, 06:14 PM
Thanks John! Question, how accurate have you found Easton's factory spine location dots?
12-05-2005, 06:30 PM
I have never found them to be off (by my fairly inaccurate "hand method") by enough to worry about, Allen. I'd be very interested if you find a batch for which that isn't true.
Normally I worry most about finding the right spine alignment on their XX75 Legacy shafts with the nock taper. You can always rotate a uni-nock in one of their XX78 shafts and fine-tune flight. But for glue-on nocks it helps to get it right to begin with.
To answer your question I can't remember ever finding a shaft what was mis-marked.
Bushcraft The most consistantly spined arrows that I have found are easton acc's. I shot some ac superslims this year and they seem to be good also. Pricey but worth it to me. DEW
12-06-2005, 04:11 PM
Thanks for the heads up DEW. Even though the XX78's have been extremely accurate for me, I have thought about going to carbon or AC. I've got a bunch of XX78's to shoot up and should be through them and ready for a new couple dozen arrows come June. It'll be interesting to see what the industry comes up with between now and then.
On a different note, does anyone know of a nock that will deflect a following arrow? I like shooting into a group instead of picking points on my Block, but have found it frustrating (and yet a little satisfying) to blow out the nock end of perfectly good arrows, thereby rendering them useless. The last time I went out I blew up two of my target arrows. If the nock had some kind of hard internal element that would remain intact (and removable after impact) while the nock disintegrated...that would help save the shaft. Anybody know of any?
Bushcraft the only thing that I know of are pin nocks, but I'm not aware of anybody that makes them for xx78's. DEW
12-07-2005, 11:46 AM
Buy a package of 1" round stickers and shoot spots. I made a template and spraypainted spots on the backside of my block.
The first robinhood is rewarding, but then you realize you just wrecked two of your best flying arrosws--not cool.
12-07-2005, 12:31 PM
I thought about the stickers but decided to write in dime sized spots on my Block with a black sharpie. After pounding 'em enough times the spots fades or the material the writing on gets pushed into the Block.
I try and mix it up by shooting 4 or 5 shot groups for a while to see how tight I can make them at 20, 30, 40 and 50 yards and then "pick" 4 or 5 points with an "all or nothing" mindset - meaning if I didn't get within an inch of the dime sized sharpie dot at 20 and 30 yds and 1 1/2 at 40 and 50 yds, I count it as a miss. I can pretty consistently go 4 for 4 up to 40 yds but begin to get about 75% at 50. Another thing I do is finish up by shooting with time constraints. Anything to mix it up.
I find the really long range practice shooting to be the most satisfying because I know I must do everything right every single time in order to perform. I kinda go into the zen mode and it is a great way to wind down the day. I took up bowhunting for the challenge of having to get in close to the game, so even though I do practice the long range stuff for creating the muscle memory and consistent form, I would much prefer to get in the 20-30 yd range for the real-world shot. Have the long shot in the bag, but strive for closer proximity, right? A lot can happen from release to impact, so I want to be close. After I have a few kills in the bag, I'll take up the irreducibility of the longbow and home-made wooden arrows.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Originally posted by Bushcraft:
I try and mix it up by shooting 4 or 5 shot groups for a while to see how tight I can make them at 20, 30, 40 and 50 yards and then "pick" 4 or 5 points with an "all or nothing" mindset - meaning if I didn't get within an inch of the dime sized sharpie dot at 20 and 30 yds and 1 1/2 at 40 and 50 yds, I count it as a miss. I can pretty consistently go 4 for 4 up to 40 yds but begin to get about 75% at 50. Another thing I do is finish up by shooting with time constraints. Anything to mix it up. </div></div>I did much the same last summer with my Black Hole target...I sray painted 4 rows of 3 dots on the face of the target. When my wife was in the yard I would have her call out the dot for me to shoot at. Best I did was the first time...3 for 4 from 40 yards at a 1 1/2" dots. Probably couldn't do that again if my life depended on it.
Mixing it up definitely helps...one shot groups...shoot and walk from 10 yards out to 50 stopping in between the known marks...shooting from 70 just for the fun of it...it's all good. I can hardly wait 'till spring to try this with the recurve.
12-07-2005, 03:22 PM
I am fortunate to have a field archery course about 3 miles from my door. Target butts from 7 to 80 yards. This is complimented by a stretch of sandy river bottom that not only is a great place to shoot judos, but broadheads as well.
When the sun stays up long enough, you'll find me there 2 or 3 times a week. But not just yet, I have a couple more hunts to take care of this winter.
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