Arrow spine paradox

[coldwinterlake]

Hi!

I've been trying to determine what arrow spine would be correct for me. Stu Miller's dynamic spine calculator suggests aluminum spine of 340, 3rivers selection charts suggest about 400 and I've "successfully" shot also 500 spine arrows from that very same bow. It's centershot RC and about 55# at my draw lenght.
Camohunter 2117s seems to be weak, but I'm not sure if it really is.
I'm using 125 grain heads and 37grain inserts.
I've been wondering where and how do you guys get those 150gr or so inserts and so heavy points. 150gr points are the heaviest that I've ever seen.
If I shot 500 spine arrows with 250gr point like some of you here, my arrows would bump of the shelf.

[9 Shocks]

I shoot a 55lb centaur longbow.  Also cut to center I believe.  I got great arrow flight out to 40 yards with Easton super slim 400 spined arrows cut to 28.25 with 200 grain points.

As for a Aluminum...I would have thought that a 2018 would have been a good arrow for you to try.  Shoot a lot of different arrows!

[J. Holden]

It's a little work and you need a grain scale, but, when I was shooting alluminums I took the inserts out.  I then went to the hardware store and found some long screws that would fit in the bottom of the insert.

I screwed them into the bottom of the insert, just a few threads, and weighed them.  I cut off the head of the screw and whatever else I needed to match find the desired weight.

I then epoxied the screw into the insert.  Around the end of the screw, where it was cut, I wrapped electrical tape so it was snug against the walls of the shaft.  

Re-insert your insert and you now have FOC.  Hope that helps.

For heavier tips look at 3 Rivers web site.  I believe they have quit a few selections.

-Jeremy

[J. Holden]

Forgot to mention, Stu Miller is right on with his calculator.  I cut down some wood arrows I was wanting to shoot.  They fly like darts now that I have them matching Stu's calculator!  Stick with it and trust it.

-Jeremy

[seabound]

It all depends on the length of your arrow and draw. How long are you shooting?

[coldwinterlake]

my draw is 29,5" and arrows have been usually 31" but I think I'll use full lenght arrows from now on.
How long am I shooting? Do you mean the distance I usually shoot? It varies, my normal practise distance is anywhere fron 10 yards to 40 yards. When 3D shooting, longest shots are somewhat 60+ yards. 40 yards would be my overall answer, maybe.
I used to shoot camohunter 2016's and they were like rubber bands despite I had only 100 grain points in them. 2213's turned out to be weak when shot without feathers.
My goal is to find one (aluminum)arrow that would produce about 11gpp and would fly true without feathers also.
Stu miller's calculator suggests 340 spined 32" arrows with 125gr points and 37 (default) inserts. I already ordered dozen of those but I've become sceptical because it seems to be MUCH stiffer than those arrows you other here are using. I can't believe my bow and arrows have different laws of physics  :D
My form should be right and release seems to be quite clean.

[coldwinterlake]

And thanks for the weight tip Jeremy, sounds handy

[seabound]

I've been using 2018's and 2117's cut to 31.5" with 150-200gr tips, both fly great out of similar poundage bows. I'd probably start with 2018's though, they seem to be better tuned.

[coldwinterlake]

Thank you all for your replies. I have now solved all of my tuning issues and the answer is actually suprising...
I used to shoot 3 under and the bow i shoot is martin hunter, and with my draw length it's about 55 pounds.
I didn't like the sound what the bow used to make when shooting an arrow. The arrows seemed to be either stiff or weak but never okay. I used to get my 3rd finger sore after shooting and actually every aspect of my shooting seemed to be little off....
And the conclusion..... I tried split shooting today after 3 hours of 3D shooting 3 under. I went to see my parents and just before I left I took my bow and shot few arrows split fingered. Everything seemed to be perfect and for that reason I continued for 2,5 hours. The bow was quieter than never before, ALL the spines from 500 to 340 were OK and everything felt just perfect. I tried to shoot some arrows 3 under style to make sure that this was the issue and it was it.
It seems to me, that because of the timing of the limbs, my tuning was impossible. Now the Hunter works as it should. And for the record, my brace height was
7.5" and nock point was 1". Easton Camohunter 2117 (400 spine) flew like darts with 100 grain heads.

[AkDan]

dumb curiosity of mine, but what was the tiller at the fades?  

I know some bows are obnoxious to tune due to design and the shooter using it (style).  Other bows are extremely forgiving (generally way more than one reason).