# How does one find the "Stiff" Line of an Arrow Shaft?



## swbuckmaster (Dec 20, 2005)

Finding the dynamic spine will allow your arrow to leave the bow flexing the same way every time with every arrow. Its the only way for each of your arrows to hit the same hole at 20-30-40 and beyond. 
You cannot imho find the dynamic spine without actually shooting the arrow. The best tool for this is with a hooter shooter. See bowcast video with south cox. 
http://m.youtube.com/results?q=tunning arrows on a hooter shooter#/watch?v=ETBidXgLLug 
The second best way to do this is by getting on arrow to bullet hole with a bare shaft at 4 yards and then pick up the next arrow and shoot it. If it wont bullet hole "most wont" then you need to twist the nock until it will. This type of tunning cant be done if you cant get your bow to bullet hole or if you cant shoot consistently enough. 

You can also take your bow and shoot it at say 40 yards. Mark your arrows and label the impact areas of each arrow with its number. You will notice a pattern in your group. One arrow might always hit high. One might hit low ect. 

If the dynamic spin on your arrows aren't lined up when you attach a fixed blade head to your arrows it will grab the air differently and deviate at launcharrows thus opening up your groups. 

Imho non of this can be done with a spine tester. Imho the arrow needs to be shot. 

Also if your the type of shooter that enjoys shooting all your arrows at the same spot banging your arrows together your going to change the dynamic spine by doing this and have to check them more frequently. 

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## straddleridge (Apr 28, 2010)

Not the strong side, but I use the weak side up

http://www.archerytalk.com/vb/showthread.php?t=1537989


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## Buffalo freak (Jul 29, 2012)

Or you can use a spine checker. Like a RAM. Spin the arrows and use the dial indicator to indetify the stuff side of the arrow. Iv always had best luck with putting this stiff side up and puttin my cock vane on this line. Hope this helps


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## swbuckmaster (Dec 20, 2005)

Stradleridge
Did you use or build the jig in the photos. I cant get that video to run on my phone and the photos are to blury to see how it works.


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## straddleridge (Apr 28, 2010)

*weak side tester*

I built 2 jigs. One is portable and the other is similar to the one in the video. In the video Glucklicher actually checked for the weak side by compressing an arrow between a table and a wall. The important thing is to put field tips in both ends of the shaft and do not impede the arrows ability to bend. I mean don't drill a hole for the tip to sit in. Have the tips both contact a hard surface before compressing. Next is a sketch of the portable version.









picture of the non-portable tester









On the non portable tester I put a metal u bracket with 20 strands of 452x so I can test for the weak side with the nock in place. Both fixtures agree almost all of the time.


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## Ancient Archer (Sep 25, 2008)

After watching the video ( http://www.archerytalk.com/vb/showthread.php?t=1537989 ), it appears that a perfect end-to-end alignment of the shaft isn't necessary to establish the bend to determine the weak or strong side/line of the shaft. Therefore, is there any reason why a long pipe clamp, say 36" capacity, wouldn't serve the same purpose? And, can this test be done with a raw shaft, i.e. without a nock or tip, just bearing against the shaft ends?


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## straddleridge (Apr 28, 2010)

*pipeclamp*

Ancient Archer:

The first time I tried bending the arrow I used a pipe clamp and it works. It is just kind of clumsy to handle. See picture:









You want to put field tips with inserts inside each end of the shaft. They do not need to be glued - just loose. The reason for the field tips is so the "column" support is called "free-free" which means it is free to rotate in any direction. 

I was showing a friend how to do this and just put the field tip on a carpet and pushed straight down with the nock in the palm of my hand and for that particular arrow it worked. I mark the weak side with a dot of white paint. 

The arrow does not necissarily need to be at right angles but it is more reliable. Arrows with very consistent spine or 2 sides that are weak need to be able to freely rotate around the point. On many arrows while using field tips you can try to cause it to bend in a different direction and it will not.


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## mike 66 (Jan 21, 2010)

very nice thread here.....i think this might be better than floating the shaft in water. instead of depending on the weight of the heavy side of the shaft you put pressure on the shaft to see just what is going on....i like this.. ok Q...are you guys putting pressure in the center of the nock??? the pic above looks like its on the tips of the nock not the center....


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## straddleridge (Apr 28, 2010)

The pictures all are using shafts with an insert and field tip on each end. The picture below shows the bender with an arrow that has a nock. The bender has a bracket on the end whit 20 strands of bcy 452x which the nock sits on. Don't know if you can blow up the photo enough to see it or not.









If you look at Gluckhicher's thread he has a picture of a simple tool to insert a nock onto.


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## Ancient Archer (Sep 25, 2008)

straddleridge said:


> Ancient Archer:
> 
> The first time I tried bending the arrow I used a pipe clamp and it works. It is just kind of clumsy to handle. See picture:
> 
> ...


Thanks straddleridge & all the others.

The pipe clamp setup in your picture is "exactly" the same as mine. I did try this to determine the stiff/weak line, and as you say, it is a bit awkward, but it does work. Now I'm going to simply centerdrill, or spot drill, a shallow hole in the face of each clamp. This would keep the center holes better aligned. I don't make up many arrows, so this should work fine. I want to do this for the arrows I use on both my GT500 & my 1965 Bear Kodiak Magnun 50#/52" recurve.

Another enjoyable project to work on!

Thanks for the help.


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## Ancient Archer (Sep 25, 2008)

PS I'm thinking of aligning the stiff side to the left as it comes off the bow, i.e. 90° to the string/9 o'clock position, which means the cock feather for arrows on my GT500 will be vertical & 90° to the stiff side. For my recurve, I would still keep the stiff side in the same relative 90° position to the string, but that means the cock feather will also be 90° to the string. This way, if paper tuning the bow suggests that the arrow is under-spined, and I can't resolve this it with lighter tips, or shorter shafts, then perhaps rotating the shaft 180° so the stiff side is to the right might help.

Or, I could do just the opposite to start off with. What do you think? Would there be a preferred benefit one side or the other?


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## straddleridge (Apr 28, 2010)

*weak side*

This is contraversial. Everyone has an opinion and they are often different

With carbon arrows the strong side is not necessarily opposite the weak side because the carbon fibers are wrapped. Aluminum arrows always have the strong side opposite the weak side - they are extruded.

I orient my arrows (compound bow) with the weak side up - the thought being that they normally bend away from the rest. I have measured friction between the arrow and the rest and it is so small I don't believe it is a factor. 

The attached graph shows the same 3 arrows (color same for same arrow) with the weak side up and the weak side down. The graph in no way indicates accuracy - just relative position. You can see that the orientation causes a difference of 3/4". This data was taken using my shooting machine at 20 yards. Being a graph the circles are considerably smaller than the arrow actually is. If they were drawn to scale the arrows are nearly in the same hole or at least partly in the same hole.









My conclusion from this data is that weak side up or weak side down doesn't make much of a difference but it is very important that the arrows are all oriented the same way.

With a recurve I would guess you would want the weak side out away from the bow with the cock vane away from the bow


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## swbuckmaster (Dec 20, 2005)

I would think a recurve would be more critical because they seem to like a weaker arrow then a compound does. 

i would also orient the stiff side up on a compound. If you dont the blade thickness and angle will become more critical especially if a human is the one shooting it. A machine can shoot a well tunned set of arrows out if a piss poor timed, tiller jacked up high right tearing paper tare all into the same hole. It however wont do the same if the arrows are not tuned. 


I think im going to make one of these jigs. Might save me some time tuning arrows. 

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## mike 66 (Jan 21, 2010)

very nice thread, thank you.. this will give me something to play with now..... mike


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## Ancient Archer (Sep 25, 2008)

Good point on the carbon arrows, I overlooked that. After reading more of your feedback, I'm going to start with the weak side/cock feather up on the compound & with the weak side/cock feather out on the recurve. Time to "tweak" as I have some new shafts on their way.


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## Ancient Archer (Sep 25, 2008)

Good point on the carbon arrows, I overlooked that. I'm going to start with the weak side/cock feather up on the compound & with the weak side/cock feather out on the recurve. I don't know what to expect to see for results as my shooting probably isn't as consistent as you guys, especially with the recurve since I just recently took it up again, but it's always better to start off on the right foot. Time to "tweak" as I have some new shafts on their way.


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## swbuckmaster (Dec 20, 2005)

Just finished with mine. It looks like if i mark the side of the arrow that bends out away from the pipe. I can let the weight off and twist the arrow and test it again. The side i marked definitely seems to always bend out. So it would appear to be working. Ill have to check them with a hooter shooter to see if it is indeed working. However for 30 bucks in materials i think its better than doing nothing to your arrows. 

Here are a few photos of mine.


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## swbuckmaster (Dec 20, 2005)

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## swbuckmaster (Dec 20, 2005)

Maybe i spoke too soon. I think gives you false readings. Gravity makes it bend down almost every time. Or irs something else that gives you false readings. Cant figure it out. 

I can mark one side of the arrow with the arrow flexing towards the pipe. It will accuratly do this. However if you take it out and put it in 180 degrees it still bends down. If you mark your arrows off a 180 degrees and shoot it in the hooter you will end up with crap flying arrows. 

Who knows, looks like the only true way is back on the shooting machine.



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## swbuckmaster (Dec 20, 2005)

Any body know why it wont work properly? 

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## swbuckmaster (Dec 20, 2005)

Just took off the nock adapter and put two pro points into a tripple x arrow and the jig will not locate the weak or stiff side. It will put a bend in the arrow but if you mark it and take it out and put it back in a 180° you wont mark the shaft in the same spot. So unless someone can explain where im doing it incorrectly im going to write this one off as a learning experience. 

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## wv hoyt man (Feb 17, 2012)

Same thing happen to me when I tried this also last night.


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## SonnyThomas (Sep 10, 2006)

Possibly one thing you boys are missing, arrow straightness. I just went through arrow straightness thing. It sucks... The factory/company evidently has their way to check straighteness and it ain't what I call correct or at least doesn't give true straightness or run out. This said, the way your jig is, the arrow heavy side may be at X location and the pressure exert may be slightly off center. Thus, arrow bending at a different location.

Two other manners of finding the stiff side of the arrow. One, look inside the shaft of carbon arrows. There will be a line which is, I guess, the overlap. This is said to be the heavy/stiff side. The second way to check for the stiff side is to float the arrows in water. Plug each end with nocks, 90 degrees opposite of each other. Heavy/stiff side will the down side.

Just went through spine stuff in General Discussion. By and large, if one chooses a good spine for their bow the average shooter would be hard pressed to know the difference of the weak or stiff side. Of a couple of times I have nock tuned through shooting. Yes, one or two arrows wouldn't group well with majority. I indexed the nock for each vane until the arrow behaved. I have even changed the nock of ill grouping arrows and corrected the arrow. Just recently I had one arrow that did not want to group, period. The arrow was fletched to the stiff side of the arrow. I did all that I could, indexed the nock, tried a different nock, even tried a different pin bushing. Disgusted, I destroyed the arrow - arrow gone, no worries, no mind games.


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## swbuckmaster (Dec 20, 2005)

floating arrows only works on aluminum arrows. 

Im going to go out on a limb and say you cant tell where the stiff side is on a carbon arrow by looking inside the arrow BUT ill check it out tomorrow.

Average shooters may not know any different in arrows but when you put those same arrows in a hooter shooter and only half of them barley jar lick the ten its easy for those average shooters to see why they need to fix there arrows.

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## straddleridge (Apr 28, 2010)

sawbuckmaster:

If you look at the original "glucklicher" thread post #18, I had the same problem with the arrows bending down. I made a jig not using a pipe clamp that I could easily stand on end and found that If stood on end the weak side was much more repeatable. My conclusion at that time and still is that gravity was playing a role. I measured the spine on some of the arrows and concluded that arrows with more consistent spine tended to always bend down with the jig horizontal.

I find that the "portable" tester from post#6 above is more repeatable. Apparently the "string" holding the nock in place has some effect on a jig with that tool. This kind of bothers me because it seems more like a real world condition. 

I have done quite a bit of testing with my shooting machine and in my opinion it seems to indicate that I get the best results by using the "weak side" method. Occasionally I get an arrow that does not behave the same as the majority. Usually these arrows appear to "twist" when compressed.

Another thing that has happened is when practicing I have noticed an occasional arrow that I have a problem with accuracy wise. I have found arrows where the weak side has changed. If this happens it is after a lot of shots. Can't put a real number on it, but I would guess it is in the hundreds. The last dozen arrow I bought and tested had a measured average spine change over 360 degrees of .008" with a minimum of .003" and a maximum of .012". If an arrow has a maximum spine change of .003" over 360 degrees it may be relatively easy to wear the arrow to where the weak side spine changes.


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## SonnyThomas (Sep 10, 2006)

*How does one find the "Stiff" Line of an Arrow Shaft?Reply to Thread.*



swbuckmaster said:


> floating arrows only works on aluminum arrows.
> 
> Im going to go out on a limb and say you cant tell where the stiff side is on a carbon arrow by looking inside the arrow BUT ill check it out tomorrow.
> 
> ...


1 - Floating carbon arrows seems spoke of a lot for not working.
2- I have not looked into the normal carbon diameter arrows, like CX 250s or 350s, but CXLs do have a "polished" line easily seen. Supposedly, Victory and a couple other manufacturers note their label having the center line of the stiff part of the arrow. I've checked and yes, the label pretty much matches the line on the inside of the shaft.
3- I am a average shooter. I've thrown (yes, thrown) arrows together and have done dang well, placing and winning probably more than my share. And this in 3D, Indoors, Outdoor target and Field.

Of other average shooters, they don't compete, only over 3 million of them. Even organization members (NFAA, IBO, ASA), some 60,000 of them, don't compete or compete all that much. All you have to do is look the numbers at state and national level. The vast majority of shooters just want a place to shoot, have fun.

I don't have a problem with anyone trying to get the best of anything to excell in archery. I just don't believe in burdening the newbie or average shooter with "super tuning" anything.


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## swbuckmaster (Dec 20, 2005)

I mounted my jig verticle and i couldn't get any arrow to repeat. I tried gold tip arrows i tried two different aluminum arrows and i tried some pse carbon arrows. I tried them with the nock jig and i tried them with just points in each end. Just didn't happen with me. Wish it did!

In the video you see gutlicker has a white vane glued to the middle of the shaft. Thats the only reason his arrows bend in the same spot every time. He biased his data!

I will agree with you saying an arrow will change it's weak side over time because i've seen it happen. 

I have a few friends who are pros and they wont shoot a shoot without making sure all their arrows will hit the same hole with a hooter shooter. 


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## swbuckmaster (Dec 20, 2005)

SonnyThomas said:


> I don't have a problem with anyone trying to get the best of anything to excell in archery. I just don't believe in burdening the newbie or average shooter with "super tuning" anything.


I dont believe in burdening any shooter except myself and my kids with super tuning either. If i can tune are arrows and are equipment the best it can be then it just comes down to us. I simple want to take all of the human factor out as much as possible. For spots all i want is a bow that aims easy by adding weight to stabalizers in certain spots, draw length to shooter for best hold and arrows coming out without contact. Bullet holes aren't necessary unless im tuning arrows for spine. I cant tune the fat ones this way cause there two stiff. They tune best through the hooter.

Other people can tune their stuff how ever they want. 



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## straddleridge (Apr 28, 2010)

swbuckmaster:

I agree with you - if I can get part of an inch by tuning I will take it - I certainly need it.

I don't understand why bending does not work for you. It works for me I would guess at least 95% of the time and I don't have a fletch in the middle of the shaft to mark it. 

The basis for this method is the studys of Leonhard Euler who was a german mathematition in the 16th century. He developed beam/column theory. Many of his formulas are still used today in architechure. An arrow qualifies as a uniform medium column and his studies say that when a uniform medium column has an increasing axial force it will bend towards the weak side. He also developed equations to predect the deflection of a horizontal beam which is supported on both ends with a vertical force applied to its center. (spine tester).

The only thing I can think of is that somehow you may be restricting the movement of the tip. It must be free rotate away from its axis. When I first started measuring arrows by bending them I had this problem and almost gave it up. For instance I put the tip in a 1/8" hole which restricted the rotation of the arrow tip. What I do now is just dimple a small piece of steel with a 1/4" drill so I can line up the arrow and keep it in place.


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## swbuckmaster (Dec 20, 2005)

I used a center punch for my holes. It allows me to put the tips in the same spot every time and it should be so small it shouldn't have contact issues. So i dont know why it wont work either. Maybe myjig jig applies pressure inconsistently who knows. 




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## SonnyThomas (Sep 10, 2006)

You know, there may be a way. Check a arrow your way and get a general idea, mark the arrow, and then find some one with a lathe. Okay, you can set up lathe easy for center point to center point. I mean, I'm talking virtually perfect center. Then the feed brought in would do the same thing the clamps do, but with precision, no applying pressure off center.


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## straddleridge (Apr 28, 2010)

I think it may be the center punch. Flat metal will work. I used a 1/4" drill to make a dimple in the metal so that the field tip contacts nothing - it is free to rotate around its axis. This thing is normally very forgiving - normally the pressure does not have to be perfectly down the axis. But nothing can stop the field tip from rotating or it will not work. I believe with a center punch part of the field tip may be touching the side of the indentation from the center punch and that will stop it from working.

Most arrows i can lean them about 30 degrees opposite the weak side and they will still bend weak side out. Some arrows tend to twist - that is they seem to start to bend in one direction and end up about 30 to 40 degrees off. These are the arrows I don't trust. There are not many of them - maybe 10%. I suspect this may be due to a "crooked" arrow where the weak side is different than the "high" side.


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## straddleridge (Apr 28, 2010)

*weak side*

Just to make it clear when I say the arrow must be free to rotate and mentioning a 1/4" dimple I made this sketch:


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## swbuckmaster (Dec 20, 2005)

Ill try the 1/4 inch drill and im also going to measure the exact center of my clamps. I really do want this to work. 

I just wont have time to do it until later this week

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## SonnyThomas (Sep 10, 2006)

May just work. The thing is, like the lathe, no offset pressure to effect bend.


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## bfelver (May 13, 2012)

i really like this way of finding the weak side of a arrow . i think this way will be more accurate then using a ram spine tester and easier


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## Ancient Archer (Sep 25, 2008)

I just received a half dozen Easton N-Fused Axis 500 shafts & was anxious to check for the weak side. The shafts were uncut at 31" and used the HIT inserts. So, I just inserted a FT at each end. The fit the ID of the shaft perfectly & rotated freely.

I used a pipe clamp similar to that above. In each clamping face I laid out & centerdrilled a spot for the field tip, shallow enough so the only contact was the point of the FT. The location of the spotted holes on each clamping face is the same so that the whole clamp can be placed on its side to keep the clamp faces & the spotted holes aligned to each other. Also, because the clamp on the screw end had about 1/16" clearance, the clamping face would tilt upwards a bit when clamping. So I added a "shim" of clear vinyl tubing with a 1/6" wall thickness & installed it on the "back side" between the pipe & the clamp wall to take up the slack & keep the clamping face vertical when clamping.

I tested each of the (6) arrows & had the same results for all shafts. _They all bent downwards_. Gravity did indeed affect the results.

So I clamped & plumbed the pipe in a vertical position. Voila! It worked. Repeated testing confirmed the original bend for each arrow.

I'm going to check the weak side of all my other arrows & refletch accordingly. Since they are already made up, I should be able to simply cut off the threaded portion of a "test" FT for the end with the glued-in insert & insert it into the insert. It should then fit perfectly & rotate freely within the insert. The nock end will just have an assembled insert & FP without glue. Both ends should rotate freely.

Gotta go - Gotta check - Gotta fletch!


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## bfelver (May 13, 2012)

i tried it on carbon express arrows didnt work for me . put points in both ends applied pressure arrow flexed i was able to rotate arrow on points bend did not change


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## Bearlee (Dec 24, 2009)

bfelver said:


> i tried it on carbon express arrows didnt work for me . put points in both ends applied pressure arrow flexed i was able to rotate arrow on points bend did not change


that means it did work, it was always the same, so you found the weak side.


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## swbuckmaster (Dec 20, 2005)

Bearlee said:


> that means it did work, it was always the same, so you found the weak side.


No i think he put it in jig and the arrow bent. He than said he twisted it and the arrow didn't flex another direction. It cant flex another direction when its flexed. He should have marked the high or low side and than took it out twisted it 180 degrees put it back in and flexed it again. Do this several times. If it bent in exact same spot every time he could say it worked.

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## straddleridge (Apr 28, 2010)

I just tried what bfelver did with 2 arrows using my portable weak side tester from post #6. For me it worked on both arrows. That is the marked side stayed bent out as I rotated the arrow. I would not recommend doing it this way.

With the portable tester I test in a manner exactly the way swbuckmaster described in post #41. 

I can try to force the arrow to bend in a different direction by releasing the pressure and manipulating the top part of the fixture with my wrists and it will still bend in the same direction. It will still bend out at the marked side.


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## wishiwashuntin (Feb 20, 2010)

I went to golfperfect.com and bought a golf shaft spine tester and it works great. Very easy, and affordable mounts right to a work bench.


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## bfelver (May 13, 2012)

with arrow flexed [points dont move i can rotate shaft on points and bend does not change always same direction ] when i read this post it sounded real good and thought was a good idea . after trying a little test i wont be trusting this method


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## straddleridge (Apr 28, 2010)

bfelver:

I suggest you do this test correctly. The way both swbuckmaster and I have explained and the way it would really happen in a bow. 

flex the arrow and mark the side where it bends out.
release the pressure from the arrow so it is no longer flexed
turn the arrow 180 degrees or what ever angle you want
put pressure on the arrow again till it flexes
the spot you put on the arrow should be flexed out


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## bfelver (May 13, 2012)

straddleridge i tried what u just posted with marking the arrow . It did not bend the same every time . Must just be some thing with these carbon express CXL I will try a victory arrow that i have and see what happens . U act like im trying to put u down IM not Im always up for learning new things


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## straddleridge (Apr 28, 2010)

bfelver - No I don't think you are trying to put me down.

What concerns me is that done correctly this test cannot possibly fail. It is a law of physics. It was defined by Euler and Bernoulli which stated simply says that a uniform column (and an arrow qualifies) with increasing axial force will always bend towards the weak side. You can even calculate the force required to cause it to bend. You can also calculate the arrows vibration frequency which is particularly use for traditional finger shooters. It is the physical law that arrow spine is based on.

The question is not just for you but anyone - is the test done correctly and if so does it help arrow flight to align the weak side the same way on all arrows?


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## swbuckmaster (Dec 20, 2005)

I just cant get my clamp to work at all.

Maybe its because it wont press square every time. Dont know, ive mounted it vertically drilled the holes ect. 

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## Rantz (May 17, 2012)

*How my teacup spine tester found my stiff sides*

Okay it wasn't really teacups, but I did use two matching coffee cups.

Nuts&Bolts suggested this as a quick and easy way to support the arrows in a way that would allow you to smoothly rotate them and not need to be concerned with them moving sideways and moving the arrow out from underneath the indicator.

















Then buy an indicator dial from some place like harbor freight. I got this one: http://www.harborfreight.com/1-inch-sae-metric-digital-indicator-93295.html It was $24 after I used a 20% off coupon. They have an analog one for $15.
Then you need a way to hold the indicator steady. Yes, you could fabricate a bracket and put your arrow supports on it as well, but I wanted to do it as fast as possible. So I went ahead and picked up the magenetic base multipositional stand as well for the indicator. It was $13: http://www.harborfreight.com/multipositional-magnetic-base-with-fine-adjustment-5645.html

So that's $37 (not counting tax) for my setup. It sets up rather quickly. You just set out your coffee cups and position your indicator on its stand.

Put your coffee cups right on the lip of a table or 2x4 (I used my messy workbench). I then used a practice bow string I made a while back to loop around the arrow (You can use whatever string like material you want) and then used another scale to weigh out roughly 2 lbs of sockets on their storage bar. I ended up with 2.02 lbs, but figured whatever since I just wanted to find the stiff side and not the exact spine. I hung that weight on the string.









Before I hung the weight on the string, I positioned the dial halfway between the coffee cups and zeroed it out. Then I hung the weight and proceeded to rotate the shaft little by little and found the side that had the least bending. I did each shaft at least 2 laps to confirm I had the correct spot. On my fatboys, about 2/3 of the arrows had the stiff side somewhere going through the "fatboy" label and the other 1/3 had the stiff side going through the "easton" portion of the label.

Voila. Stiff side found (and marked with a marker on the shaft) so that I can orient all of my arrows the same way when I go to fletch them. Granted I'll only be shooting these fatboys primarily indoors and it may not make a material difference, but it's the confidence that comes from doing it (and the experience to use on my next fletching of outdoor fita distance arrrows) that counts.

-Rantz


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## nuts&bolts (Mar 25, 2005)

Rantz said:


> Okay it wasn't really teacups, but I did use two matching coffee cups.
> 
> Nuts&Bolts suggested this as a quick and easy way to support the arrows in a way that would allow you to smoothly rotate them and not need to be concerned with them moving sideways and moving the arrow out from underneath the indicator.
> 
> ...


EXCELLENT work, Rantz.

Check is in the mail, right?

hehehehe.


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## Rantz (May 17, 2012)

nuts&bolts said:


> EXCELLENT work, Rantz.
> 
> Check is in the mail, right?
> 
> hehehehe.


Just don't cash it! :set1_rolf2:
I can't afford all of the help/information that you have provided me with. You are awesome :cheers:


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## Bearlee (Dec 24, 2009)

I still think That the WEAK side is the best way to orient your arrow. 
When compressed a column bends toward the weak side, 
this is the arrow and it will do the same. 
so in a compund bow 
that we have bare shaft tuned to remove lateral nock travel 
and we do not induce any side to side movement, 
the only movement left is up and down. 

The most consistent we can get is to allow the arrow to bend in this direction. 
either up or down, 
as we know the stiff side of the carbon arrow may not be opposite the weak side, 
we do not care where the stiff is located, 
only where the weak side is located. 

Now whether you place weak up or weak down would depend on your bow, 
but I believe that with my top cam hitting slightly before bottom, 
that means bottom cam has the last influence on arrow.
so the arrow is pulled from the bottom last
meaning that the weakest side needs to be in tension rather than compression
which places the weak side on top.

JMHO

Bearlee


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## Bearlee (Dec 24, 2009)

straddleridge said:


> The attached graph shows the same 3 arrows (color same for same arrow) with the weak side up and the weak side down. The graph in no way indicates accuracy - just relative position. You can see that the orientation causes a difference of 3/4". This data was taken using my shooting machine at 20 yards.
> View attachment 1526967
> 
> 
> ...



From straddleridge's post and experiment we can deduce that weak side up or down could influence effieciency of absorption of energy of the arrow.

at 20 yards it is on the rise in the arc of the arrow cycle 
therefore, a lower hit would be deemed faster

from his findings we see that a lower hit was caused by weak side up.

We can surmise that at greater distances than 20 yards, say 90 meters for fita,
that one would get better groupings out of a more efficient arrow.


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## cjorg (Aug 26, 2012)

I can mark my weak side, then rotate the shaft 10, 70, 130 degrees just some randomness place, retest and sometimes the shaft will flex to 180 degrees opposite from my first mark. It is really consistent but they are 180 from each other. Any recommendations?


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## straddleridge (Apr 28, 2010)

I have seen this happen. For me it is pretty rare. My guess is that the weakness (spine) of the opposite sides is very close. In an earlier post there is a sketch of what I call my portable weak side tester. It you look at it, it has a "plumb bob" to aid in making sure that you are applying the force along the axis of the arrow. Normally it doesn't seem to matter, but on an occassional arrow that behaves like this one it does.


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## cjorg (Aug 26, 2012)

I am shooting Gold Tip XD Hunters and they are all doing it. I think the next thing I will try is hang a weight from them and measure diff, hopefully I can get it that way.


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## fordtough (Sep 7, 2012)

Did this last night on my lathe between centers. After marking the high side of the bend on every arrow I went through and did them again.

Bent to my line on everyone of em.

These are black eagle carnivores.


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## StonyAT (Jan 28, 2014)

*Finding the weak point in seconds*

Hi
I am a newcomer in compound archery. I started about 4 months ago with it but I do pretty well meanwhile. I am a fly fishing pro and from this background I know a bit about carbon and the so called overlap which is also a point of controversial discussion when it comes to rod building. Of course modern carbon rods and arrows are using different wrappings in different angles and with different materials after the first process is done but the basic principal both are manufactured the same way. 

A carbon mat is wrapped around a steel core. So there is a point where the mat ends(compare it with wrapping a silotape around a pencil). Where the tape ends there is one layer of material more on the pencil than on the other side. Therefore at this point the pencil is stronger when you try to bend it along this axis. When rotating the arrow under pressure as soon as you have passed this strongest point the arrow flips to the side(strongest ridge position is quite difficult to maintain) in direction to the weakest point with least material which is usually 90° from this point (depending where you started and ended the wrapping). In this position the arrow is stable(it does not want to leave this position any more). 

Please recognize that there are two strong points of the arrow (where the mat ends and opposite of it) and two weak points. One of the stronger sides is less strong than the other. It is the same with the weaker sides(one is less weak once again depending where the wrapping started). So there is a weak diagonal and a strong diagonal. 
To find out the weakest point of an arrow usually takes me not much more than 5 seconds without any machinery at all by just rolling the arrow tip over the edge of a table supporting the other end with pointer and middle finger from below and pressing the arrow down with the other hand using a sliding movement which causes the arrow to escape into its weakest position. This method was mentioned in the thread but nobody took much notice of it. With this method rod builders find the overlap of the rod parts to place the guides on the fly rod correctly. There are machines on the market to find this weakest point exactly and they might be of course more accurate than the method I use but this is not the point I am really interested in. 

What I am interested in is where to put the top vane to get best arrow performance. Should the weak diagonal of the arrow be alined vertically or horizontally? 
If you put the stiff diagonal of the arrow alined with the bowstring the arrow does not bend that much when leaving the bow string which might result in less possibilities of touching the arrow rest(when using a fall away rest this is anyway nearly impossible ) but a carbon arrow under pressure wants to bend in direction of its weakest point and having reached that goal it would keep this position. 
So my question is: Isn’t it better to allow the arrow to screw into the direction it wants to bend right away and let it move on this way, which for me means that it will find a stable flight faster? Or is it better to have the stiffer diagonal alined with the bowstring? For me the first one would make more sense although with the stiff diagonal on top the first punch would be caught by the strong side before the arrow would escape into the weaker direction after. 

Please tell me which approach is correct and where the major vane on a compoind arrow should be positioned correctly from the physical point of view and ballistic research. Thanks!

Greetings from Switzerland


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## SonnyThomas (Sep 10, 2006)

If something works...use it. As I noted before I fletch to the burnished line in side the arrow shaft. The "line" is wide so I go for the center of it. Said to be the strong/stiff side I fletch it up. I've spoke with some, PMed and in threads wondered of which is better. The general concensus was it didn't matter.
Anyway, the pics are of 34 and 35 yards with a Pearson TX4 churning 293 fps and a Pearson MarXman churning 284 fps. Arrows are the same, older Harvest Time Archery HT3s with .400 spine. I checked FOC in two different manners. One gave 6.023% and the other gave 6.32%. The 2nd pic was shot with my TX4 using a 8" NAP ShockBlocker. The others were shot with my MarXman while testing weights for the front stab and back bar. Weather was not ideal and shooting with a coat on is not ideal either. The one without a target I have labeled; "cold and stupid." After 15 shots my riser felt like ice...
I'd say I was holding right at 1 1/2" groups and feel I had spine of the arrows where it should be.....


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## bbjavelina (Jan 30, 2005)

Just a couple more thoughts;

When checking the shafts in compression, it seems to make sense to do it vertically so as to negate the effects of gravity. 

You just can't ignore whatever pre-bend the shaft may have. If the shaft looks like ")" before applying compression, you may not be finding the weak side.


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## StonyAT (Jan 28, 2014)

When I roll the shaft in my had having both ends free to turn in the direction they want to all sides are effected by gravity. Otherwise the horizontal arrow and golf club spline testers would not work. But they do. You rotate the arrow sitting on ball bearings and at the weakest point the scale shows more weight. I can feel the resistance of the arrow in the hand that presses the arrow down which does the same thing than the scale. If there is no effect at all these spine testers would not have been built. And if a top level shooter does not care about that I would wonder. Of course everyone would be happy to get arrows where these points cannot be found. When testing Victory VAP 1 arrows I recognized that the printing of the brand in relation to the weak point changes from arrow to arrow so they seem to not care at all. At least it would be helpful if top arrows would be marked with a little dot after cheching or at least are all equal when you buy them. 

For me it would make sense to have the weak side alined vertically to let the arrow fligh in his natural position as at the same time the strong sides are aside and can stabilize a bit against impact of mistakes by the shooter as at full draw horizontal impact to the arrow is easier to be created than vertical.


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## [email protected] (Feb 17, 2013)

I could see how the ends of the shafts not being square would mess this whole idea up fast.

Weak side up or down? I assume up or down as long as it is aligned with the bowstring. Interesting thought though, which way would lessen the chances of an arrow going through someones hand if it broke durring the shot?


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## dw'struth (Mar 14, 2008)

Marked for later...as if I needed something else to obsess over!


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## bbjavelina (Jan 30, 2005)

Probably most of you realize there is an 11 page discussion in the GAD forum just now. spine indexing, I think. a good read.

I'd like to summarize my thoughts here;

Compression test should be done vertically. 
A bent shaft (and most are) can't be depended on to show the weak side. 
The more uniform your shafts, the less repeatable a compression test will be. 

best of luck to you.


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## elkbow69 (May 7, 2010)

i have used the "fishin" rod method of finding stiff spine side for the last few dozen arrows Ive fletched prior to cutting them of I spin, mark, spin, again and check, one mark is always at 11-1 oclock. I guess the KISS method works pretty well too.


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