Tuning question

[McDave]

[attachment=1,msg2793115]

The bare shafts in the above photo were shot from the same bow with the same configuration: a 47# takedown recurve with the nock placed at 5/8" above square.  This is not just a random grouping.  I shot many times with each bare shaft, and the above grouping is representative of the way each bare shaft hits.  The top two are 5575 GT, the top one cut to 30" and the bottom one to 29".  Both have the same spine, as closely as I can measure.  Two of the bottom three are 3555 GT, and the black one is a GT 500.  All are cut to 29".  The 3555 that is more horizontal is stiffer than the one that is more nock high, and the 500 is slightly weaker than the 3555's.  All bare shafts have 145 grain points.

The nock right, nock left variations (not shown) are unremarkable.  Stiffer shafts are slightly more nock right than weaker shafts, although nothing like the nock high variations shown.  The 30" 5575 is the closest to being centered R/L, but none of them are that far off.

I am puzzled that I get so much nock high/low variation without moving the nock point.  Although it is not obvious in the photo, the 5575 cut to 29" consistently gets slightly nock low, the stiffer of the two 3555's consistently gets about 3-5 degrees nock high, while the 30" 5575, the 500 and the other 3555 are consistently 10 degrees or more nock high.

Any ideas on why this is happening would be appreciated.

[Pine]

It's possible that your nocking point is too high and your getting a bounce effect.
I have seen some bow need it as low as 3/16 .
You could play with it and see.
Just a guess. 

[McDave]

I never thought of getting a bounce effect from the nock point being too high.  I always thought a bounce came from too low of a nock point.  I don't think I ever tried a nock point less than 1/2". I'll have to play with that.

[bhylton]

if i shoot bareshafts with a canted bow (right handed) a weak spine shows nock high, stiff is nock low. the nock kick is all relative to the cant of the bow and how the arrow flexes around the riser and shelf  in my experience. same could be true for false stiff, false weak ect. 

[McDave]

This could be true in my case, as the weak ones are nock high and the stiff ones are nock low. That's why I tried 5575's, because the only way I could get rid of nock high with the 3555's was with the one that happened to be stiffer than the others.  And the stiffer 5575, the 29" one, is the most nock low of all. I didn't think I was canting that much, but it is a possibility.

[McDave]

[attachment=1]

I shot the same 5 bare shafts again, being careful to hold the bow vertical with each shot.  The top and the bottom arrows are both 5575's. The top arrow is 30", and the bottom one is 29".  Evidently, the 30" 5575 is the weakest arrow of the group and the 29" 5575 is the stiffest, including the 3555's, based on the left/right deviations.  The 30" 5575 also has the highest nock high, while the 29" 5575 has the lowest.  The best is the 3555 that is unusually stiff, and I would make all my arrows out of that one, if I could, but it is evidently one of a kind.

I am beginning to think that there is a correlation between arrow stiffness and nock high, although I don't know why that should be.

[old_goat2]

if i shoot bareshafts with a canted bow (right handed) a weak spine shows nock high, stiff is nock low. the nock kick is all relative to the cant of the bow and how the arrow flexes around the riser and shelf  in my experience. same could be true for false stiff, false weak ect.

This is my first thought

[Pete McMiller]

Dave,

Do all the nocks fit the same on the string?  Some aren't tighter are they?

Two nocking points?

Split or 3 under?  5/8 would be high for me shooting split - I always set up at 7/16.

Do you have a spine tester to confirm each arrow's spine?

[Bisch]

Umm, not to get off topic here, but what the heck is that in the doorway in the background???? Or is that a mirrored wall? Anyway, I'm talking about the brown curved looking thing?

Bisch


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[rraming]

Umm, not to get off topic here, but what the heck is that in the doorway in the background???? Or is that a mirrored wall? Anyway, I'm talking about the brown curved looking thing?

Bisch


Sent from my iPhone using Tapatalk Pro

think that is wine cork art

[Bisch]

Umm, not to get off topic here, but what the heck is that in the doorway in the background???? Or is that a mirrored wall? Anyway, I'm talking about the brown curved looking thing?

Bisch


Sent from my iPhone using Tapatalk Pro

think that is wine cork art

Well, there's the answer then! If McDave drank all that wine then tried to tune his bow, no wonder those bare shafts are all wonky!!!! [emoji38][emoji38][emoji38]

Bisch


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[Roy from Pa]

Well, there's the answer then! If McDave drank all that wine then tried to tune his bow, no wonder those bare shafts are all wonky!!!!

Bisch

LOL Bisch

[McDave]

I made that about 20 years ago out of some wine corks we had saved.  My cat at the time thought it made a good scratching post, so she shredded the bottom couple of feet or so.  Oh well, at least she appreciated my art.  Ol' cat just wandered off one day and never came back....I miss that ol' cat.

[McDave]

[attachment=1,msg2793234]

Anyway, to continue with the tuning project, the photo above is of 3 5575 shafts.  As Gold Tip is wont to do, they all are of slightly different spines.  The top one measures 92 on my spine tester, while the bottom two measure 82 and 80.  I doubt if those are the actual spines, but at least it gives me a basis for comparison.  It seems that the higher the spine, the more horizontal the shaft.  In fact, the stiffest spined one on top actually shows a slight nock low orientation, which resulted in the high impact.  If only they were spined correctly, that would be the end of my quest, but of course they all show somewhat stiff.

The best spine for the bow is 3555, but I have been unable to get rid of the nock high.  I reduce the nock point until I get the nock high orientation shown in the first photo I posted, and then further lowering of the nock point does not have any effect on the nock high. 

I was surprised that an over-spined bare shaft, 5575, will shoot flat, or even nock low, but a correctly spined bare shaft will not shoot flat.

In answer to some earlier questions, all the nocks are for the same GT shafts, but I did switch a few back and forth to see if I noticed any difference, which I didn't.  I shoot 3 fingers under, and a 5/8-3/4 nock height seems to be fairly normal for 3 under.  I use two tied-on nocks: one above and one below the arrow nock.  In any event, as I mentioned, reducing the nock height does not reduce the nock high, at least with 3555's.  I have an old spine tester which uses a weight and a deflection indicator, which will at least give me relative differences.

The 5575's are not that bad.  I probably just have to fool around with the length and point weight some until I find some combination that has acceptable up/down and sideways bare shaft deflection.  Either that or try some other brand of shaft.

[Bisch]

McDave, sorry for the fun I was having a while ago!!! As far as GT spine consistency goes, from my experience spine testing hundreds of GT shafts, the only way you are going to get closely matched sets is to buy lots of shafts and spine each one, and separate them into close groups. That is what I used to do once I got a spine tester, and saw the difference myself!!! That is the sole reason I quit shooting GT shafts. I felt that, for nearly $100/dz of raw shafts, the QC should be better. It was not uncommon for me to have the weakest and stiffest shafts in a dz be nearly .100" difference, and that was not acceptable to me. The shafts I was using back then (XT Hunter black) also had a definite stiff side, and many would vary around the shaft as you spun it on the spine tester as much as .020". Also, every GT shaft I tested was stiffer than the spine printed on the shaft.

The shaft I changed to is even more expensive, but every single shaft I have tested, from multiple dozens bought at different times, has all been within the same .010 spine range!!!

Bisch

[McDave]

No prob, Bisch!  I enjoy the camaraderie on here as much as I enjoy the rest of it.

I think for this particular bow, the "average" GT 3555 shaft is too weak, while the GT 5575 is too stiff.  I have one GT 3555 shaft that I stumbled on by accident that is stiffer than average, and works perfectly, but I don't have any others like that one.  From my measurements, the new GT 500 shaft is even a little weaker than the old GT 3555.  What shaft are you using these days?  The only reason I stick with GT is habit, and the fact that I've got a lot of GT inserts and shafts laying around.  Plus a lot of GT bare shafts, which now that I think of it may not be doing me much good, because I may be bare shafting with one spine and making arrows with another, even though both are marked the same.

[Bisch]

If you are using those 3555's at full length, and they are slightly weak, you should just be able to cut them off a tad bit to make them stiff enough.

I am shooting Easton Axis Full Metal Jackets now. The reason: well, I was given a dz shafts in a trade for a bit of work. I was in a slump at the time, and looking for any change I could find to help make things better. Once I put those shafts on the spine tester and saw how consistent the spine was, making the change was easy. Also, with no scientific proof other than seeing it with my own eyes, I firmly believe I get way better penetration with the skinnier shafts. (Everything I do and set up with this is for hunting. I don't have a target setup and a hunting setup. I just have a hunting setup that I use for everything.)

Also, I don't want to come across like I am bashing the GT's. I shot those shafts for a looooooong time, and I can't tell you how many critters I killed with them. They work, as attested by the thousands of folks who still use them. I am just anal about my setups, and could not deal with the inconsistency!

Bisch

[archeryprof]

I stopped shooting GT's because of problems with consistency and durability.I still have a half dozen or so that are free for the asking.

[OkKeith]

Archeryprof-

Sent you a PM re: the arrows.

Thanks,

OkKeith

[kenneth butler]

McDave, you have helped me out in the past. May I suggest you watch Ken Beck's bare shaft tuning on Youtube. Very good demo. You seemed to have covered the bases 2 nocking points etc. He explains why some folks can't tune out nock high. It could be contact with the outer edge of the shelf if it is a little wide. He will explain all the rest and demo a week,stiff,and just right arrow. You have too many variations of shafts for me to keep up with. I would pick what should be the proper spine and work with it. Ken the other one,LoL can explain it much better that I. I have talked with him several times he is a great guy. good luck.>>>--->Ken