# Strange Tuning Issues



## Bob Furman (May 16, 2012)

Just throwing this out to see what other ideas you have. I have pretty much ran out of ideas on why this is happening,

Specs:

Bow Weight: 36#
Arrows: Mckinney II 950
Draw Length:	28.5
Point Wt.	100 g
Brace Height:	8.5

Shooting with those specs I'm still showing a stiff shaft. I have re-checked that my center shot is correct more than once lately. My aperture is to left of the arrow by about 3/8” (I shoot Right Handed). Generally I’m pretty good at tuning, but this one is driving me nuts. I did notice that I have been putting some finger pressure on the arrow at Set so I have paid attention to that more. That seems to of helped some. And yes, I have also ensured that my bow is on Plane as outlined in http://www.archerytalk.com/vb/showthread.php?t=1703779&highlight=plane

Bare shaft @ 30 meters are landing about 4-6" to the left.

Paper tuning I get about a 1/2" tear to the right.

All this is with my Beiter Plunger set with the light spring pretty much as light as I can get it.

According to the Carbon Tech Arrow Chart, my current setup is about two sizes weak. (http://www.carbontecharrows.com/target/target-arrow-chart/). And just for a reality check I also tried some Mckinney II 725 shafdts. As expected they were way stiff. Bare shaft almost missing the target at 30 meters.



Any suggestions?


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## c365 (May 15, 2013)

I'm far from the person who knows but as a comparison with my setup. We're both about the same DL

At 38# I shoot 750's with 90gr points.

The aperture 3/8" to the left of arrow sounds unusual to me. I guess mine is about vertically center (inline) to the arrow.

And the plunger tension is fairly stiff, about 12 oz.


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## Seattlepop (Dec 8, 2003)

I would go by the CT arrow chart. My bet is that your arrows are so weak you are getting a false stiff result.


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## leschrader (Jun 26, 2012)

Bob,
Depending on the weight you have on the nock end and the footing on the tip, they could be stiff. What type vanes and nocks are you using and how long is the footing on the tip?
Did you start with the stiff plunger, everything "in line" and set the limb weight to the arrows? I had to ask.....sorry.


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## midwayarcherywi (Sep 24, 2006)

Seattlepop said:


> I would go by the CT arrow chart. My bet is that your arrows are so weak you are getting a false stiff result.


That would be my guess as well. Tough to know without being there and working with it though.


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## Greysides (Jun 10, 2009)

Can you drop poundage and see what happens?

Any marks on the arrows/fletching/riser? Any noise?


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## cc46 (Jan 22, 2005)

I'm with Seattlepop on this one. 

A stiff reading with a soft plunger usually means the plunger bottoms out against the bow. Having the sight ring that far left is a symptom of the same. 

I'd try --- Add a bit of stiffness to the plunger, so that it can't bottom out. Then heavy up your string and/or nock end of the arrow, and see if the bare shafts starts to move back over.


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## RickBac (Sep 18, 2011)

Robert, your arrows are too weak. You should be between 650 and 725. Especially with your draw length.

Stiffen up your plunger a little and try the 725's again. Do it from about 15 meters at first and see how they hit.


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## TomG (Dec 4, 2002)

Bob, 
What equipment do you have and what brace height?


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## Bob Furman (May 16, 2012)

leschrader said:


> Bob,
> Depending on the weight you have on the nock end and the footing on the tip, they could be stiff. What type vanes and nocks are you using and how long is the footing on the tip?
> Did you start with the stiff plunger, everything "in line" and set the limb weight to the arrows? I had to ask.....sorry.


Wav Vanes, Easton Pin Nocks, Point is the standard 100 grain S/S point unmodified. I normally start with a medium spring tension and bare paper tune and bare shaft for final settings. If at best, my sight aperture is normally to the left of the arrow slightly.


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## Bob Furman (May 16, 2012)

Greysides said:


> Can you drop poundage and see what happens?
> 
> Any marks on the arrows/fletching/riser? Any noise?


dropping poundage by 2-3# results in a larger right tear as expected.


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## Bob Furman (May 16, 2012)

TomG said:


> Bob,
> What equipment do you have and what brace height?


Hoyt Hpx 68"

Specs:

Bow Weight: 36#
Limb Rating: 34
Arrows: Mckinney II 950
Draw Length: 28.5
Point Wt. 100 g
Brace Height: 8.5


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## Bob Furman (May 16, 2012)

RickBac said:


> Robert, your arrows are too weak. You should be between 650 and 725. Especially with your draw length.
> 
> Stiffen up your plunger a little and try the 725's again. Do it from about 15 meters at first and see how they hit.


Did that earlier just paper tuning at a close distance and I had a large right tear to the right. About 4". I know what the chart says and I know what I should be shooting, but when I go to a weaker spine the tear gets less and a stiffer spine the tear gets worse. I can do some bare shaft at 15/20 yards tomorrow.


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## Mika Savola (Sep 2, 2008)

Aperture to the left of string at RH is usually a sign of weak arrow. With 36# and shaft length between 28-29" you should be using a parallel shaft with .720-.800 spine


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## TomG (Dec 4, 2002)

Bob Furman said:


> Hoyt Hpx 68"
> 
> Specs:
> 
> ...


I can't see anything here that would explain what you are experiencing. The brace is a bit high for a HPX but reducing it would make the situation worse. 

I am having a somewhat similar situation but I know it is caused by my Uukha limbs. My x10 450 that would tune at 44# and 90 grains points with my Xpression limbs now require 49lbs and 150 grains to tune with my Uukha.


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## RickBac (Sep 18, 2011)

Robert, forget the paper tune.

Put the sight back to center. Set the plunger back to medium. Bareshaft tune. you should be much closer. Fine tune from there.

Do you have Gary's Recurve tuning guidelines?


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## MJAnderson68 (Nov 15, 2013)

TomG said:


> I am having a somewhat similar situation but I know it is caused by my Uukha limbs. My x10 450 that would tune at 44# and 90 grains points with my Xpression limbs now require 49lbs and 150 grains to tune with my Uukha.


Just curious as someone who just bought some Uukha EX1s and plan on doing some tuning this weekend --- what's up with the limbs that they would require that?


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## TomG (Dec 4, 2002)

MJAnderson68 said:


> Just curious as someone who just bought some Uukha EX1s and plan on doing some tuning this weekend --- what's up with the limbs that they would require that?


Trying not to hijack the thread but in essence, the limbs are much stiffer in rotation. The will reduce the side to side movement of the string, thus making the arrow react stiffer.


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## theminoritydude (Feb 11, 2013)

TomG said:


> I am having a somewhat similar situation but I know it is caused by my Uukha limbs. My x10 450 that would tune at 44# and 90 grains points with my Xpression limbs now require 49lbs and 150 grains to tune with my Uukha.


May I ask, is your Uukha lighter in mass, especially as it gets closer to the string notch, when compared to your previous limbs?


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## Greysides (Jun 10, 2009)

Is paper tuning appropriate for a recurve? I thought it was more applicable to compounds.


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## chrstphr (Nov 23, 2005)

Greysides said:


> Is paper tuning appropriate for a recurve? I thought it was more applicable to compounds.


paper tuning is not that good for fingers, recurve. the paradox will give false reads, and any bullet holes are merely when the arrow is in the center of the fletch. Move paper back 4 feet and you get a tear again. Bareshaft tuning is better for recurve and fingers. 


Chris


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## Seattlepop (Dec 8, 2003)

Greysides said:


> Is paper tuning appropriate for a recurve? I thought it was more applicable to compounds.


I agree with Chris, but not with his interpretation. For example, a bullet hole cannot be made with an arrow that is not flying straight (think nodal alignment). 

I put red marker on the point and shoot different distances, I find 10' and 15' and points in between are good. If the arrow is flying straight, you will get a 1" tear with the point (red mark) on the left of the tear and then on the right of the tear as the shaft oscillates and you change distance. 

If your bare shaft is flying good, you an actually see the red mark moving from from one side of the 1" tear to the other as you change the shooting distance. 

Then you take it outside and *tune*. 


So, you can't *tune*, but you can do valuable testing through paper. Bob F for example, at the stage he is at, can use paper *testing* to see if his arrow is tunable. 

In other words, a bare shaft that makes a 6" tear shooting 10' to 15' through paper is not going to suddenly fly straight out of the bow when you take it outside.

Just don't call it *tuning*.


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## leschrader (Jun 26, 2012)

Bob,
As was suggested, put sight and center shot to center with a hard/firm plunger and adjust your limbs to match your arrows bareshaft to fletched. Don't worry about point of impact, just so long as the bare shaft and fletched are close. Then play with centershot and plunger pressure for point of impact and arrow flight. I've tried to take a shortcut to save time and wound up chasing the tune all over the place until I went back to the the basics and did it like I should have in the first place. According to the numbers you've given, they should be weak so you might not be able to adjust the limbs enough, so you could try dropping tip weight to 80gr and raising the tail weight 20gr with heavier fletching. The FOC should still be OK at those settings. You'll chase your tail (literally) trying to use paper tuning with a recurve. You can have a perfect hole thru the paper and still have the tail all over the place, depending on where in the arrow oscillation it impacted the paper(distance from bow). 

Uukha EX1's I had tuned close to normal limbs.....great limbs.


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## Seattlepop (Dec 8, 2003)

leschrader said:


> Bob,
> As was suggested, put sight and center shot to center with a hard/firm plunger and adjust your limbs to match your arrows bareshaft to fletched. Don't worry about point of impact, just so long as the bare shaft and fletched are close. Then play with centershot and plunger pressure for point of impact and arrow flight. I've tried to take a shortcut to save time and wound up chasing the tune all over the place until I went back to the the basics and did it like I should have in the first place. According to the numbers you've given, they should be weak so you might not be able to adjust the limbs enough, so you could try dropping tip weight to 80gr and raising the tail weight 20gr with heavier fletching. The FOC should still be OK at those settings. You'll chase your tail (literally) trying to use paper tuning with a recurve. *You can have a perfect hole thru the paper and still have the tail all over the place*, depending on where in the arrow oscillation it impacted the paper(distance from bow).
> 
> Uukha EX1's I had tuned close to normal limbs.....great limbs.


You need to distinguish between oscillation and rotation when you read the tear. Its a simple matter of knowing what you are seeing. When you change distances as I do, as I said 10' to 15' and points in between seem to work well, you can see the difference between the two.

Edited to add: If you get a 1" tear all all distances, does it matter if it is caused by either oscillation or rotation? I would say that is a tunable arrow and that is all I expect to get from paper *testing*.


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## Seattlepop (Dec 8, 2003)

At the risk of beating a lethargic horse, this crude visual is what I am talking about. All three shafts are oscillating, two are also rotating. Only one can make a bullet hole.

View attachment 2110255


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## leschrader (Jun 26, 2012)

Seattlepop,
Good visual. So, your Sayingggg......paper tuning can be used for rotational problems exceeding the amplitude of the oscillation of the arrow, unless you know the "node" point distances for your bow arrow combination (10' and 15' for yours). Then you should be able to get a "bullet hole" at those points with a properly tuned arrow. I see what your talking about, but wouldn't the "node" point distances change with velocity, arrow length and spine value? Wouldn't this be kind of a "tough read" for a person trying to get an inital tune on a bow/arrow combination? Your right about showing up easily on paper with the tune being way out of tolerance, but Bob said he was only out about 6 inches on bare shaft testing at 30yrds......not really that far out. I can see where this could be a good tool for final tune and characterization of a bow/arrow system and establishing a base line for future arrow tuning on that bow system. But, as they say, if it works for you, use it.......

Bob, sorry about side tracking your inital question......


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## Bob Furman (May 16, 2012)

Greysides said:


> Can you drop poundage and see what happens?
> 
> Any marks on the arrows/fletching/riser? Any noise?


Sorry, I forgot to report to this. Dropping poundage stiffens the shaft as expected. Bare shafts hitting more left. I have checked for clearance issues and nothing found.


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## Seattlepop (Dec 8, 2003)

leschrader said:


> Seattlepop,
> Good visual. So, your Sayingggg......paper tuning can be used for *rotational problems exceeding the amplitude of the oscillation of the arrow*, unless you know the "node" point distances for your bow arrow combination (10' and 15' for yours). Then you should be able to get a "bullet hole" at those points with a properly tuned arrow. I see what your talking about, but wouldn't the "node" point distances change with velocity, arrow length and spine value? Wouldn't this be kind of a "tough read" for a person trying to get an inital tune on a bow/arrow combination? Your right about showing up easily on paper with the tune being way out of tolerance, but Bob said he was only out about 6 inches on bare shaft testing at 30yrds......not really that far out. I can see where this could be a good tool for final tune and characterization of a bow/arrow system and establishing a base line for future arrow tuning on that bow system. But, as they say, if it works for you, use it.......
> 
> Bob, sorry about side tracking your inital question......


Well, yes, no, maybe. Rotation and oscillation are completely independent in this instance. Oscillation is what can cause, or miss, having a bullet hole from a bare shaft that comes out of the bow oriented as straight as can be. That is dependent on the distance from the paper. The only interest I have in nodes is as a concept for describing how an oscillating arrow can fly straight. The length of the bare shaft is not relevant to that concept. Spine matters only to the degree that a weak shaft may have a wider oscillation than a stiff shaft, so your tear could be slightly wider. 

A bare shaft that kicks (rotates) left or right out of the bow will not be able to make a bullet hole. Different distances from the paper may affect the length of the tear, but it always be a left or right tear. If the rotation is so slight as to come close to making a bullet hole when shot at the right distance, who cares? That is when you take it outside and tune it. 

I think some people think that a rotating arrow will swing back to the other side, a full rotation if you will, and mid-rotation can cause a bullet hole. I have never seen a bare shaft rotate that fast within 10'. A fletched arrow, perhaps (although I doubt it), but I only paper *test* with bare shafts. 

BF did mention a 4" tear in one post, but yes, if all you have is a 1/2" bare shaft tear at distances between 10' and 15' I would say that is a very tunable arrow. However, in BF's case, he is not getting the expected results when he makes adjustments and I find that to be the first clue that I am out of tuning range and I am getting false readings. I also know from my own 36.5# bow that with a one inch longer DL I can tune .570 ACE's, 110gr points. To tune a .950 spine I would have to cut them several inches too short. As it has been suggested, there is something else going on there. 

BTW, here is another crudely drawn visual of how the point of a tuned arrow can be "walked" across the tear by shooting paper at different distances. If the (cough) nodes are aligned, the tear will not be any larger at any distance. 

View attachment 2110733


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## c365 (May 15, 2013)

Seems nothing has been resolved. At this point I would do the Tune for Tens. It'll tell you immediately if the arrow is too stiff or too weak. One suggestion is, Tune for Tens will come to a step where you paper test. I eliminated that and just shot a bareshaft a number of times into a decent target. You can tell just by the bareshaft angle what adjustment you need to make arrow spine and nock height.

I got the best tune ever using Tune for Tens. Before that I went round and round, haphazardly making adjustments hoping. My arrows were slightly too stiff and by adjusting the point weight and bareshafting, got the shafts to fly straight to where you only see the nock end in the target.

http://www.texasarchery.org/BoardMembers/RickStonebrakerPages/TuningForTens/TuningForTens.html

Try it, nothing to lose, wonderful shooting to gain.


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## theminoritydude (Feb 11, 2013)

I don't recommend the paper test. Consider the situation where the wave propagates at the same speed as the initial exit velocity as the arrow/bareshaft, but in the opposite direction. Referenced to the position of the paper, you get effectively, a standing wave. Though you might not get a "bullet hole", it's rather improbable, what you might get is something very close to that, giving you the idea that the bow is somewhat tuned, when in fact it doesn't in anyway say anything.


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## Bob Furman (May 16, 2012)

c365 said:


> Seems nothing has been resolved. At this point I would do the Tune for Tens. It'll tell you immediately if the arrow is too stiff or too weak. One suggestion is, Tune for Tens will come to a step where you paper test. I eliminated that and just shot a bareshaft a number of times into a decent target. You can tell just by the bareshaft angle what adjustment you need to make arrow spine and nock height.
> 
> I got the best tune ever using Tune for Tens. Before that I went round and round, haphazardly making adjustments hoping. My arrows were slightly too stiff and by adjusting the point weight and bareshafting, got the shafts to fly straight to where you only see the nock end in the target.
> 
> ...


That is basically what I normally do or at the very least bare shaft from 30 - 70 meters. I will post shortly on my results.


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## Bob Furman (May 16, 2012)

So to shed some more light on this....First off guys, this is not my first rodeo. Tuning is (normally) pretty simple if you follow the proper steps. Btw, I just did the paper tuning because I was at home in the garage and I didn't want to freak the Neighbors out...They freak out if garbage cans are left out too long, I can imagine how they would react to a guy shooting a bow the the length of the driveway into his garage....Another note, I can normally get a pretty good basic tune using the paper tuning method (I have used that on and off over the last 20+ years). Yes, that is a 122 cm patch target face.

Now onto the tuning issues. Although I had a pretty good idea that something else is going on here, I went ahead and reset my sight, arrow and plunger to center (Tuning for Tens method with stiff plunger). This is from about 15 meters with my McKinney II 725 shafts. Sorry, I just had one bare shaft on hand and I really didn't feel like butchering any good shafts today.











Although the pic taken of the McKinney II 950's didn't come out, I ended up with a light spring and kept everything inline and they were grouping ever so slightly to the left.


So what forces are at work here???


Btw, the limbs in question are Formula Carbon 720's. One thing I did notice is the top limb's notch at the bottom of the limb is off center, but since the shims have been moved to ensure the limbs are aligned, I'm not sure if that is causing any issues.


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## Shinken (Nov 3, 2012)

Any possibility that the arrows are mislabeled? Do you have access to a spine tester?


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## dchan (Jun 29, 2004)

One clearance check to do that is a little different.

Powder the tail of your arrows or lipstick the shaft from about 5 inches to the nock. Primarily on the side that faces the riser.

Check for contact with the plunger or if it gets scrapped off. 

If this reveals nothing then set your plunger full stiff and report back results. 

I'm with many of the posters that the plunger is bottoming out and leading you the wrong way.

DC


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## hooktonboy (Nov 21, 2007)

Shooting with a clicker? Is the button soft enough to get compressed and throw the arrows left when the clicker pressure comes off? Sight 3/8" left of the arrow has you aiming a long way right...


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## Bob Furman (May 16, 2012)

dchan said:


> One clearance check to do that is a little different.
> 
> Powder the tail of your arrows or lipstick the shaft from about 5 inches to the nock. Primarily on the side that faces the riser.
> 
> ...


Nice catch, I will try that later today.


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## Bob Furman (May 16, 2012)

hooktonboy said:


> Shooting with a clicker? Is the button soft enough to get compressed and throw the arrows left when the clicker pressure comes off? Sight 3/8" left of the arrow has you aiming a long way right...


Possible, but I get the same results without the clicker.


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## hooktonboy (Nov 21, 2007)

Bob Furman said:


> Possible, but I get the same results without the clicker.


At least its an easy one to check for


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## Seattlepop (Dec 8, 2003)

FWIW, 

@ 36#, 28.5 DL, 8.5" BH...

Archer's Advantage shows .950 MII's would have to be cut to 22" (raw shaft) to tune. 

Give or take an inch.


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## RickBac (Sep 18, 2011)

Bob, on top of setting the plunger to stiff. Do you have another plunger? Just in case your main plunger has a problem.


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## chrstphr (Nov 23, 2005)

Some guys need stiffer than normal arrows based in ther release. Some guys newd weaker than normal. Charts are not exact but a generalised ballpark to start.

For most people, the easton charts are stiff and most go 1 to 3 spines down to get an atrow that works. For me the easton chart is 3 spines weak and i have to shoot a much stiffer arrow than recommended.

It is entirely possible that his release is such that the charts dont work for him either. 

If the 950s are slightly stiff for him, then that may be what he needs to shoot.


Chris


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## c365 (May 15, 2013)

OK, in a previous post Bob mentioned he's been shooting for 20 years. What spine arrows was he shooting all these years that were apparently good? And I assume the MKII are new? and why did he choose a 950 spine? where did that spine info come from?
Just curious, lots of questions remain.


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## dchan (Jun 29, 2004)

chrstphr said:


> Some guys need stiffer than normal arrows based in ther release. Some guys newd weaker than normal. Charts are not exact but a generalised ballpark to start. This is true
> 
> For most people, the easton charts are stiff and most go 1 to 3 spines down to get an atrow that works. For me the easton chart is 3 spines weak and i have to shoot a much stiffer arrow than recommended. Sadly this NORMALLY means a poor or plucked release
> 
> ...


Generally the cleaner your release, the weaker the spine required. (not always the case however) But MUCH more important is how consistent your release is. IF you pluck your release exactly the same every time, GREAT.. I wish I could do that..

DC


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## chrstphr (Nov 23, 2005)

dchan said:


> Generally the cleaner your release, the weaker the spine required. (not always the case however) But MUCH more important is how consistent your release is. IF you pluck your release exactly the same every time, GREAT.. I wish I could do that..
> 
> DC


it is the opposite. The cleaner the release the stiffer the arrow you need. 



DK Lieu said:


> The way an arrow tunes is greatly affected by what the archer does. This is why the arrow shaft spine tuning charts should be considered only a starting point for proper selection of shaft spine. The spine that is finally needed depends on what the archer does as part of his/her regular technique. As long as that technique is consistent, there is probably not one spine that is more correct than another. Examples of thing that can affect the behavior of the arrow upon its loose from the draw hand are: how stiff the fingers are, how much pluck there is on the string, and how much forward collapse occurs. * Stiffer fingers tend displace the center-of-mass of the arrow away from the bow, causing the arrow to behave stiffer by sending the arrow away from the bow. The stiffer behavior of the arrow can be compensated by choosing a weaker spine for the shaft. A shaft with a weaker spine will bend more, and thus its center-of mass will be displaced less. * I know this is my own problem, but I don’t worry about it too much because I am pretty consistent with my finger stiffness. * I know that when I am working on relaxing my draw hand more, my arrows start behaving weaker as the release become cleaner. When I start getting tired, my fingers stiffen up more, and then I started sending arrows left (since I’m RH). As of now, I use one spine size weaker than what the charts recommend. * In the case of a pluck, the center-of mass of the arrow is pulled toward the bow, causing the arrow to travel in that direction and thus behave weaker. This effect can be compensated by choosing a stiffer spine for the shaft. Generally, plucking is easy to spot and easy to correct. Stiff release fingers are difficult to spot and therefore a more difficult problem to identify, and perhaps even more difficult to correct. * I believe that this is the reason why many people believe the Easton spine selection charts yield spine recommendations that are too stiff. The charts seem to work better for higher level archers who have developed clean releases and thus requiring stiffer spines, and not so well for beginners who are still developing their release techniques*.



http://www.archerytalk.com/vb/showthread.php?t=2266262&highlight=release

http://www.archerytalk.com/vb/showthread.php?t=2221019


Chris


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## Bob Furman (May 16, 2012)

c365 said:


> OK, in a previous post Bob mentioned he's been shooting for 20 years. What spine arrows was he shooting all these years that were apparently good? And I assume the MKII are new? and why did he choose a 950 spine? where did that spine info come from?
> Just curious, lots of questions remain.


When I started shooting the MkII's about a year ago I was shooting my Hoyt Avalon Plus with 32# limbs. They were actually backed way out and I was drawing about 30.5 pounds. I slowly increased my draw weight to about 34 or so. Funny you site mention it, I got my Avalon Plus out today set the draw weight at 30#, set center shot and taped a make shift match stick sight set at center and low and behold my MkII 850 (fletched and bare shaft) were hitting the middle. 

Now to figure out why my Hoyt Hpx @ 36# won't tune 725's???


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## Seattlepop (Dec 8, 2003)

Bob Furman said:


> When I started shooting the MkII's about a year ago I was shooting my Hoyt Avalon Plus with 32# limbs. They were actually backed way out and I was drawing about 30.5 pounds. I slowly increased my draw weight to about 34 or so. Funny you site mention it, I got my Avalon Plus out today set the draw weight at 30#, set center shot and taped a make shift match stick sight set at center and low and behold my MkII 850 (fletched and bare shaft) were hitting the middle.
> 
> *Now to figure out why my Hoyt Hpx @ 36# won't tune 725's??*?


Ummm, they're weak?

View attachment 2111322


This was with a raw shaft of 27", if yours are longer they would be more weak.


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## Bob Furman (May 16, 2012)

RickBac said:


> Bob, on top of setting the plunger to stiff. Do you have another plunger? Just in case your main plunger has a problem.


An older Caviler plunger that I use now on my Avalon Plus. It appears to be working just fine.


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## dchan (Jun 29, 2004)

There are actually two sides of the release dynamic spine issue. 

If you look JUST at the physics of an arrow. IF you were able to push the arrow perfectly straight (no paradox) the arrow would not bend at all. (this would be the perfect clean release)

If you tune the bow to match a consistent pluck, by moving the point of the arrow to match how far you push the arrow to the left (rh shooter) so that as it leaves your fingers in line, then the path of the string as it moves left and right as it corrects you would need a stiffer arrow to keep it from bending the arrow too much.

If you tune the bow to match a very clean release, (closer to centershot) and you occasionally pluck the string (displace it more) you will also need a stiffer arrow to keep from over flexing the arrow, however you would be able to shoot a weaker arrow because the amount of flex you will create as you release cleanly, will not bend the arrow as much.

This is why tuning is so much of a "dark art" So much depends on the shooter, and there are so many variables that can make it better or worse.

Like Limbwalker, for the given DW/DL/Arrow length, if everything is constant (including centershot setup), I am usually a spine or 2 weaker with arrows than most of the others on the range. However when I pluck my release, I know right away, and the arrow almost always ends up right (dynamically weak)

DC


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## dchan (Jun 29, 2004)

Depending on your rig configuration it can go the other way too. A clean release and too much offset will require a stiffer arrow to spine properly. If you take the "arrow should be to the left of the string" as "the only way", you are going to have problems. If you have a real clean release (not pushing the arrow far enough to the left to get it to flex properly) and the offset is not set up correctly, you may need a stiffer arrow as well. Again, it's all about the shooter and why I try not to spend too much time dwelling on "perfect tune". Consistent form will trump a perfect tune every time.. Even a poorly tuned bow (spine match) will put all the arrows in the same place if your form is consistent. It may be less forgiving, but even clearance problems, if consistent, will still group well.


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## chrstphr (Nov 23, 2005)

X10s work best dead center of centershot. 

I havent shot a bow with arrow left of string in years.

So i dont have any offset. I guess we have to disagree on this issue.

Chris


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## dchan (Jun 29, 2004)

If you are configuring your rig with the arrow dead center, then you will need a stiffer arrow to get proper flight. that would make sense. MOST archers use the offset to compensate for the fact that we WILL puch the arrow to the left some. How much depends on the archer. A weaker spine being shot out of a rig with a dead center configuration will bend more because we are putting the tail of the shaft out of alignment with the front and then trying to accelerate the back end of the arrow and overcome the inertia of the point. Combine that with the fact that you prefer to shoot with even heavier points, and of course your arrows need to be stiffer. 

Nothing wrong with shooting your setup this way if it works for you. It just takes a lot of tinkering and a very consistent shot to get it to work well. Most intermediates would find a configuration like that very unforgiving. 

DC


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## chrstphr (Nov 23, 2005)

dchan said:


> If you are configuring your rig with the arrow dead center, then you will need a stiffer arrow to get proper flight. that would make sense. MOST archers use the offset to compensate for the fact that we WILL puch the arrow to the left some. How much depends on the archer. A weaker spine being shot out of a rig with a dead center configuration will bend more because we are putting the tail of the shaft out of alignment with the front and then trying to accelerate the back end of the arrow and overcome the inertia of the point. Combine that with the fact that you prefer to shoot with even heavier points, and of course your arrows need to be stiffer.
> 
> Nothing wrong with shooting your setup this way if it works for you. It just takes a lot of tinkering and a very consistent shot to get it to work well. Most intermediates would find a configuration like that very unforgiving.
> 
> DC


As X10 arrows are a barrel shaft, they should have a dead center alignment for best flight. I would imagine if you polled all the archers at a USAT or Nationals shooting X10s, you will find most will have a dead of center alignment for the arrow. Couple that with the most common point used (the 100gr-120gr), and that would make your assumption that the setup is unforgiving a most common setup. Perhaps everyone is using an unforgiving setup if they shoot X10s. 

I do shoot a higher FOC than most, but the difference in weight is so slight from 100gr to 150gr ( and we are talking grains here) that the difference in spine is minimal.

I will lastly say that i think Park Sung Hyun is the best archer in the world ever, and she has the best finger release in the world. No one does it better in my opinion. Oddly she also shot an X10 arrow that is 3 spines stiffer than what the chart says she should shoot. I am in good company if i have a plucked or poor release. 


Chris


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## Bob Furman (May 16, 2012)

Well, I have managed to tune my Hoyt Avalon at 32# with the 850's with room to easily go up to 34#. So it would stand to reason that I should be able to tune my Hpx @ 36# with the 725's I have, but they are showing stiff so I'm suspecting that the limb notch at the bottom is creating tuning issues. 

In case anyone missed it, I noticed that my bottom limb notch is off about 1/8". Although my shims can compensate visually, I have a feeling it is making it hard to tune.

Does anyone know a good way I could fill in the notch and recut it properly centered of course?


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## pencarrow (Oct 3, 2003)

"In case anyone missed it, I noticed that my bottom limb notch is off about 1/8". Although my shims can compensate visually, I have a feeling it is making it hard to tune."
BINGO.
Send the limbs back......
Cheers
Fritz


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## OlyShoot (Feb 10, 2013)

Bob Furman said:


> my bottom limb notch is off about 1/8". Although my shims can compensate visually, I have a feeling it is making it hard to tune.
> 
> Does anyone know a good way I could fill in the notch and recut it properly centered of course?


Bob... What are you currently using for shims in the notch? 

I've recently experimented with shimming the limb notch. I have low cost SF Premium limbs so I was not afraid to experiment. I know one thing that will not work. One thing that sort of works, and one that I'm pretty sure will work but I'm not sure about how long it will last. Read this first to ensure you have the tools and skills before starting.

Beer can layers (you can cut it easily with a scissors these days) with thick double sticky tape layers (I used golf grip tape) sort of works but is only temporary for testing a couple of times (unless you can find some other really aggressive tape). Thin super glue with baking soda in my opinion is too fiddley. Its hard to get the glue to soda ratio right which usually ends up crumbly and doesn't stick well to the limb. The thicker super glues "used just by themselves" (like a thick varnish) seems to work best and "might" be tough enough. Get the grade that can be used for lacquer repair. Also the thicker slower setting glues have larger polymer chains and are generally tougher. The thin fast setting glues are generally more brittle. This is true for most all adhesives. Sorry I'm not consistent in this tirade. Super Glue = CA glue = Cyano Acrylate glue.

Before you start... use your best rule (or get a caliper) and measure the to notch to make sure that it is evenly centered in the limb and not skewed to one side. When you reshape the notch be sure to keep it centered evenly in the limb.

I use a piece of blue painters tape to create a tallish border (1/16" at most) around one side of limb notch, (be sure to clean out the notch first so the glue has good clean surface to stick to). I hold the limb "just snug" in a smooth jaw vice, so edge of limb faces the ceiling and face of limb is facing me. Dispense the thicker super glue in the tape frame (just like pouring concrete) then if you have to... roll it around to evenly distribute... then if you have it... use the spray activator to instantly freeze the glue. It still may take 2-3 minutes because of thickness. Otherwise you just have to wait till it cures (it could be 10-20minutes). Repeat on other side of notch. I had to really file on this surface to get to a "just tight fit". 

When its cured all the way through, remove the blue tape. Then you need to shape the cured CA glue to get a proper fit. I used a selection of hand files, you could also double-sticky some sandpaper strips (220-320 grit) to a Popsicle stick or the side of a knife. I again hold the limb just snug in a small vise so that I could shape square surfaces to the limb faces. Check your progress often. I used to caliper to measure as I was shaping, so that I could maintain a uniform spacing front of notch to back of notch, plus I found that I could do more aggressive shaping to a certain measurement... then after that... I used the actual fitting of the limb onto the Tiller bolt to determine how much to sand off. This is hard to do visually or measure... go by feel, and custom fit each limb if you are doing both.

Again another beauty of superglue is that If you file/sand too much off just place more tape and build it up again.

Its not brain surgery, but that said, its also not a 5 minute job.

ANOTHER DISCLAIMER: about super glue and your mileage will vary. I'm sensitive to CA (CyanoAcrylate) glue fumes... the day after I use it I have a slight runny nose, two days I have full on stuffyness like a severe cold, then by 3-4 days my sinus' clears up. So if you can, be careful and use good ventilation

Epoxy should work too but partial cure is at a minimum "over night". Also, in general, slower curing epoxy is tougher, fast cures are usually more brittle. And what the epoxy mfgs don't tell you is that "full complete cure" at room temp is closer to a month. Cured epoxy might be the toughest and most durable shim.

Hope this helps


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## Mika Savola (Sep 2, 2008)

I strongly believe that limb notches have nothing to do with said arrow tuning problems...


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## theminoritydude (Feb 11, 2013)

chrstphr said:


> As X10 arrows are a barrel shaft, they should have a dead center alignment for best flight...


Why is that so?


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## hooktonboy (Nov 21, 2007)

theminoritydude said:


> Why is that so?


Ok, I'll bite. I believe the thinking is that because they are barrelled, then if you are setting centre shot at brace height, then you are setting it with the thinnest part of the shaft contacting the button. So in theory, technically you are setting it slightly left, because of the barrelled effect - the shaft gets wider on the middle section so if it is still in contact, it gets pushed out more left.... But if you set it left, the effect is increased....

For me though, a good tune is a good tune. The results are in the target. I find that with the combination I use, I set pretty much dead centre with my (thin, light ACC) parallel shafts. Good flight, good groups, no contact.... but everyone's mileage will probably vary


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## hooktonboy (Nov 21, 2007)

Nobody's mentioned the HPX geometry? I've never shot one. Is it a tuning factor?


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## TomG (Dec 4, 2002)

The HPX is less deflex than most risers and normally requires a shorter brace height. A shorter brace height tends to make the arrows react stiffer. However in this case the brace height was over 8".

As a side note, I would like to see people (and manufacturers) talk about average tiller distance for limbs. This would remove the riser geometry from the equation.


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## chrstphr (Nov 23, 2005)

theminoritydude said:


> Why is that so?


because they are barreled. The ends are weaker and will flex more, the center is stiffer. That center is placed in line to target, the ends will flex and not displace the center as much. Plus real world results show that dead center placement results in better groups and arrow flight. 

Have you not experimented with this in your shooting? offset vs dead center with X10? 

Chris


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## Bob Furman (May 16, 2012)

TomG said:


> The HPX is less deflex than most risers and normally requires a shorter brace height. A shorter brace height tends to make the arrows react stiffer. However in this case the brace height was over 8".
> 
> As a side note, I would like to see people (and manufacturers) talk about average tiller distance for limbs. This would remove the riser geometry from the equation.


Just a note, that I'm shooting a 25" Riser with Medium Limbs (68" bow). Anything from 7.9" to 8.5" is recommended by Hoyt's HPX Manual (See attached screen shot from the Hoyt 2012 Manual). Also I believe normally if you are shortening your brace height (longer string or removing twists) it will cause your arrows to act weaker. Or did you mean shorten your string??? 

Btw, Hoyt and I'm guessing other Manufacturers mention the recommended Tiller offset, but to mention exact settings would be nearly impossible since the limbs are adjustable and most shooter's will customize this to suite their needs.



View attachment HPX Braceheight.pdf


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## Bob Furman (May 16, 2012)

OlyShoot;1071884570Bob... What are you currently using for shims in the notch?
I've recently experimented with shimming the limb notch. I have low cost SF Premium limbs so I was not afraid to experiment. I know one thing that will not work. One thing that sort of works said:


> Not using any shims as of yet, I have just adjusted the Hoyt dowel by moving the shims/spacers. Thanks for all the info.


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## Bob Furman (May 16, 2012)

Please see post #1

Thanks for everyone's input in previous posts.

Ok, back to these tuning issues. After getting some A/C/E 670's and getting those tuned with no issues I can only assume it's something with the McKinney II shafts and me. Anyone care to speculate on why I must shoot such a light spine as compared to the A/C/E shafts?

I did check for clearance issues and without going even lighter the best I could do was the same setup as in post #1:

Specs:

Bow Weight: 36#
Arrows:	Mckinney II 950
Draw Length:	28.5
Point Wt.	100 g
Brace Height:	8.5


Actually there is very little difference in the 850's and the 950's as far as point of impact.


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## dchan (Jun 29, 2004)

Are not McKinney II shafts parallel construction compared to ACE barrel construction?


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## Bob Furman (May 16, 2012)

dchan said:


> Are not McKinney II shafts parallel construction compared to ACE barrel construction?


Yes, but for the life of me, I can't understand why I can easily tune the Easton ACE shaft, but nothing I have done will get the McKinney II shafts tuned. Shooting 36# @ 28" all McKinney II shafts keep showing stiff. Even with a Heavy and Medium spring. I have tried the McKinney II 725, 850 and 950. they all shoot stiff. I can't imagine that a McKinney 1050 wouod work. Seems way too weak even at a lighter weight and medium length draw such as mine.


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## dchan (Jun 29, 2004)

A Parallel shaft will dynamically spine stiffer than a tapered or barreled shaft.


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## Mika Savola (Sep 2, 2008)

My rule of thumb is to always select a parallel shaft with at least .080" weaker spine than chart suggested barreled shaft...


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## Joe T (Apr 5, 2003)

Bob Furman said:


> Yes, but for the life of me, I can't understand why I can easily tune the Easton ACE shaft, but nothing I have done will get the McKinney II shafts tuned. Shooting 36# @ 28" all McKinney II shafts keep showing stiff. Even with a Heavy and Medium spring. I have tried the McKinney II 725, 850 and 950. they all shoot stiff. I can't imagine that a McKinney 1050 wouod work. Seems way too weak even at a lighter weight and medium length draw such as mine.


My guess on this (and it's pure intuition) is that the problem is the McKinney arrow is much lighter then the ACE arrow. Arrow selection charts are presumably based on the overall arrow flex rate matching the bow geometry (The Archer's Paradox requirement). The tuning however is essentially based on bow string torque on the arrow.

The string force on the arrow is proportional to the arrow's mass so you're getting much less torque in the "weak" direction with the MK2 than with the ACE. It's sort of like kicking a football filled with air and a football filled with concrete, you get the highest foot-ball force with the heavy ball.

A possible solution would be to try increase the MK2 arrow point weight.


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## Vittorio (Jul 17, 2003)

In my experience with the McKinney II, rule was to have 100 spine difference, at least, from ACE's. That means that my daughter shooting ACE 850 needed to shoot McKinney 950 to get them tuned. No special problems, then. If your bow tunes with ACE's 670, it shoul d tune with McKinney II 725 slightly stiff and 850 slightly weak. 
With same nocks and piles, remaining variables are:
1) - center shot 
2) - riser+ limbs geometry (point of return of the energy to the shaft) 

As playing with center shot has been done already, I have to assume that factor 2 has more influence than others in the issue. If power stroke comes later (last fraction of the shaft), spine of the related last part only comes into effect , and so may be this is making parallel shaft compartively stiffer . But I doubt of this, never seen before ... Why don't you post a movie of you shooting some arrows so that we can all understand better all factors involved?


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## limbwalker (Sep 26, 2003)

Regarding spine selection, I had the same experience both with McKinney II's and parallel CX arrows like the original Nano Pro and XR. You don't choose nearly as stiff a spined arrow as you would in an A/C/E or X-10


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