Arrow Spline

[Robin Kinney]

I'm shooting a Mizar riser and limbs, 12 strand dacron with just over 36 pounds on the fingers and 26.5" arrows. The Easton arrow guide as well as the Easton software calls for a 780 spline for the Easton Redline (6.3 gr/in). I purchased a dozen but was never satisfied. Trying different tip weights, and settling at 100gr., my unfletched arrows hit the target 20" to the left of my fletched arrows at 20 yards with the nocks even further to the left than the points.

I was recently loaned an unfletched Easton XX75 1913 (8.3 gr/in and spline of 733) at full factory length of 31" and four RPS tips of different weights of 85 to 125gr. I shot this arrow and different weights against a fletched Redline (I had only one XX75.) The 100gr and the 125gr both hit the target within 3" of the fletched arrow (although low due to the heavier weight). However, the XX75 with the 125gr tip left the bow perfectly straight whereas the 100gr. left the bow with the nock to the right of the point. The unfletched XX75 with the 125gr tip was so perfect that it grouped nicely (a little hard to tell with only one arrow) at 50 meters and the flight was beautiful.

Now, the question I have is how do I translate the specs. of the 31" XX75 with 125gr point to a lighter arrow, like a Redline so I can have the speed to hit the target at 70 and 90 meters? If both the XX75 and the Redline arrows were of similar weights, translation of just spline is easy since spline force is proportional to length but considering the different weights per unit length makes the calculations more difficult. Do any of you, my on-line archery mentors, have a solution?

[c3]

How long is your draw length? If you can give the button to bottom of nock distance and add 1.75" you will have the AMA draw length. This can be very different than the length of your arrows. It's definitely required to use any of the software programs to double check with.

Cheers,
Pete

[Robin Kinney]

My draw length is 26". My arrow tip is 1.5" beyond the plunger and I could possibly go another .5 to .75" longer overall and still have room for the clicker to drop.

[c3]

TAP shows that a 27" arrow with 100 grain point would require roughly a 700 spine. Maybe one of the other folks with James Parks program can run it there to confirm.

Arrows in this range are:

Navigator 710
ACE 720
ACC 3-04
X7 2012
XX75 1913
Redline 690


While all these show on the stiff side of the Easton chart, they should be pretty close for you. If you add a pound or two and or your draw gets a tad longer, you should be perfect with any of those arrows. I would start from the top of the list if you can afford it.

Cheers,
Pete

[Sandy Hancock]

My draw length is 26". My arrow tip is 1.5" beyond the plunger and I could possibly go another .5 to .75" longer overall and still have room for the clicker to drop.

Draw length is arbitrarily defined as nock throat to pivot point (=plunger for the Mizar) + 1.75". You said your arrows are 26.5" long. If your clicker is 1.5" past the plunger then your draw length is actually 26.75"

[Robin Kinney]

Good point, Sandy. Thanks for the correction.

[Robin Kinney]

Thanks, Pete. I'm currently shooting Redline 780's with 100gr. tips and they seem too stiff. They porpois through the air and an unfletched arrow hits the target about 20 inches to the left of a fletched arrow at 20 yards. Even so, they group pretty well, within maybe 18 inches at 50 meters. I'm just amazed at how well that 31" XX75 with the 125gr. point flies off the bow. I'm wondering if I'm missing something.

[Progen]

My draw length is 26". My arrow tip is 1.5" beyond the plunger and I could possibly go another .5 to .75" longer overall and still have room for the clicker to drop.

If you're shooting well with this setup, don't muck with it for the time being just to gain drawlength and poundage. That was what I did late last year. Found that my current and previous (up till 6 months ago, soldiered on for a few months from last year) clicker position varied by 2/8" which was enough to throw the form off.

Assuming that you don't mind moving your sight extension in, you should be able to reach 90 metres with all the carbon / aluminiums and carbons which Pete had suggested BUT do expect some frustration on windy days. Forget about the pure aluminiums for anything past 30 metres unless it's only for fun. The wind LOVES aluminiums. :D

It's a bit strange for your 780 Redlines with 100 grain points to shoot that stiff though because with 38lbs at my fingers, my 690 Redlines with 70 grain NIBB points shot just a LITTLE stiff. They were cut to 27 7/8" which isn't a whole world of difference from yours.

ps. It's SPINE, not SPLINE. Not the same thing. ;)

[Robin Kinney]

It is a bit strange why my 780's with 100gr points shoot so stiff. Many members of Archery-Forum have said that the software and Easton Arrow Guide put you pretty close. I wonder if there is something strange about my release.

I've considered buying a dozen XX75 1913's and shooting them for awhile but what's shooting well is a factory-length arrow of 31", well outside the range of my clicker. I'd need to regress to shooting without a clicker.

I've performed a set of first order calculations to translate the magnitude of arrow flexion at maximum acceleration from the XX75 to the Redline series. I'm hesitant to buy a dozen arrows based upon my calculations because I'm unsure of my assumptions. I know you people in Australia and South East Asia think I'm wacky up here in the States but unless you live here in a major metropolitin area (or Chula Vista, California -- U.S.A. Olympic archery team headquarters) you can't find much help when it comes to FITA target archery.

[Duss]

Just a note about spines. There is static spine and dynamic spine. When you shoot the arrow it is the dynamic spine that shows.

It means that for two arrows with the same static spine specification they might act differently if their composition is different, even for the same weight per inch. Pure carbons act more stiffly than aluminum/carbons or aluminums for example.

Just to be careful when changing arrows, do not cut them the same size even if they have the same static spine if they have different constructions.

[recurve boy]

Just to be careful when changing arrows, do not cut them the same size even if they have the same static spine if they have different constructions.

Eh? You should be cutting arrows to the same length and using a different spine.

You should be checking charts when buying arrows and not getting them based on spine.

[Duss]

Eh? You should be cutting arrows to the same length and using a different spine.

You should be checking charts when buying arrows and not getting them based on spine.

What I was driving at was : try not to start with preconceived ideas about the length if you are changing spine or arrow composition. It is better to try them out longer and cut them accordingto the tuning results.

Have you ever tried to make an arrow longer?

[recurve boy]

What I was driving at was : try not to start with preconceived ideas about the length if you are changing spine or arrow composition. It is better to try them out longer and cut them accordingto the tuning results.

Have you ever tried to make an arrow longer?


I think you'll find that this is a superior way to tune. http://www.archery-forum.com/showthread.php?t=13320&page=4

Tuning by cutting arrows sounds like it could be extremely annoying. :-/

[Duss]

Ok ok, one has to start from a "suitable length". That definition of length really fits everyone and no one at the same time.

I know very well that I could have almost any length of arrow "tune" to a bow but the "best tune" or "objective-driven tune" is something else.

My warnings were relating to an experience one of my fellow archers had. He was using ACE 520s that he was finding "stiffish" and decided to change spines. He moved over to SAME LENGTH ACE 570s and they were "weakish".

The problem mostly lies in what one wants in terms of "starting points" or "hard factors", like FOC, front node position etc.

Just like for a good cake you might have many good recipes

Another example would be the following. Since many variables are involved and they all are inter-related it makes bow-and-arrow tuning a wonderful experience.

Let us start with an arrow of lenght A + spine A + point weight A. That gives you a certain combination of node position and FOC and also a certain Berger spring tension. Depending on which factors you want to keep constant, the problem of changing the arrow type and spine in that situation has an almost infinite number of "good" solutions while there are a lesser number of optimal solutions.

Say for example that you want to have same-length arrows and keep the same Berger button spring tension. You will have to change the point weight (and/or nock weight). That also will change your FOC and node position and perhaps not towards desired values.

For example, one could have three sets of arrows that tune about the same on thesame bow with the following values : point weights in the 130-grain area, same nocks and fletchings, but 32-inch 500-spined carbon tube, 30-inch 600-spined carbon tube and 29-inch 520-spined ACE tube. However the FOCs and node positions would differ quite a bit.

Archery is like cake-making, both an art and a technique to suit everyone's needs and tastes

[recurve boy]

My warnings were relating to an experience one of my fellow archers had. He was using ACE 520s that he was finding "stiffish" and decided to change spines. He moved over to SAME LENGTH ACE 570s and they were "weakish".

You should point your friend to the link then! ;)

I think it may not point to the first page though, since I prefer latest posts first.

[Duss]

The link is OK. Thank you for it.

Like a friend of mine says so well : "Archery really is hours of fun on end, no end!!"

You should point your friend to the link then! ;)

I think it may not point to the first page though, since I prefer latest posts first.

[Progen]

Well, at least you have a Mizar with a clicker plate so the range of lengths you can play with is slightly more than those with. Like the Agulla or Gold Medallist. Of course you can always consider one of those sight mounted clickers. Lovely stuff.

[Duss]

Well, at least you have a Mizar with a clicker plate so the range of lengths you can play with is slightly more than those with. Like the Agulla or Gold Medallist. Of course you can always consider one of those sight mounted clickers. Lovely stuff.

Anyone with some aluminum, files, a drill and screws can locate the clicker anywhere one would wish to.

The sight mounted clocker, while easy to use has a huge drawback in the case of a sight that would be located close to the riser.