GT Shaft Selection

[Hashiba]

Alrighty.  After plugging some figures into Stu's calculator, I'm a bit confused.

First off, I shoot a 50#/28" TD recurve @ 29".  I have measured my shelf and its cut a full 1/4" past center.  I plan to slap a strike plate on her that will bring it to dead center.  I can tweak this if I have to.  Now onto the decision making.

I have cheap access to Gold Tip through work, and have my eye on the affordable Hunter series.  I was planning on 5575 @ around 31" with the 50 grain brass insert, a 165grain No Mercy head & 3x5" feather fletch.  This would be a 9.2 GPP arrow with a 20% FOC.

According to the calculator, I actually need to step up to the 7595 to even come close to the spine I need.  I realize these are heavy heads for what carbons are designed for, but can you guys verify by experience that such heavy points really need that kind of spine on a centershot recurve off the shelf.

[BigJim]

Those heads are not heavy and I seriously doubt you will ever shoot a 7595. My bows are cut to center and I shoot a 31" arrow (7595)with a 30.5" draw. My arrows have 100g brass inserts and 300g heads (400 up front) and I'm shooting them out of 80-85 lb bows.
Get the 5575's and if they are a little weak, bump your side plate out a tad.
good luck, bigjim

[Hashiba]

I think I really just needed someone to tell me that.  It just made no sense to me that I'd actually need that kind of spine with such a moderate bow!

[hkmp5]

Hello Hashiba,
I could be wrong hear but I think we are talking about two different animals here.  From what you said I assumed you were setting up for true "centershot" which is a strike plate position about 0.15" past center (-0.15 in the DSC).  That will drive a significaqntl;y higher dynamic spine requirement.
Big Jim is talking about "center cut" bows where when a thin strike plate is added results in a position of around 1/16 outside of center.  In that case I completely agree you will never shoot a 7595.

Perhaps you could clarify this for us so we are talking apples-to-apples.
-Stu

[Hashiba]

The shelf on my bow is cut a full 1/4" past center.  I don't yet have a strike plate on it.  I am very willing to build it up and push the contact point out a bit.

A strike plate at 0 with the 100 grain brass insert puts me 2# weak on for the 7595 @ 30" on the calc.
The 5575 reads 12LBS weak at this setting.

A strike plate at 1/16 past center with the 7595 still reads only 2# light at 30.5".

The 50 grain brass insert puts the 5575 @ 30.25" bang on.


If the above is true, then is there a best choice for tuning?  I am willing to run them up to 31" and the extra weight up front gives a 22% FOC.  I assume you can't really go overboard with FOC for hunting right?

[Shawn Leonard]

You can get away with a 500 spine cut to 30"s and that 50 grain brass insert and the 165 grain head. Most likely 31"s will be fine as well. I am shooting 600 spine out of 46-47# recurves drawn to 28.5"s so about 48-49#s 30"s long and 190 grains up front. Sorry most guys shooting carbon are overspined. 55/75 you will need all of 275 up front and 31"s long and I bet more like 325 for perfect flight. Shawn