# Arrow spine calculators?



## gjarcher (Oct 26, 2006)

I use OnTarget2! software http://www.pinwheelsoftware.com/sfa.aspx

If the OT2 software doesn't match your bare shaft planing or group tuning results, it has customizable sliders and calibration procedures to fit your setup and tuning results.

All software will only get you in the ball park. You must still do the bareshaft planing, paper testing, walkback/French tuning, and Fine Tuning (aka Group tuning). 

As far as how much is too much? FWIW, I find that I start getting tighter broadhead groups at 12% FOC and usually hunt with 14% - 15% FOC for the improved flight stability and penetration potential.

Many African PHs recommend 18% FOC for Dangerous Game. You can read some of Dr. Ashby's recent reports where he discusses the effectiveness or lack of for differing FOC.
http://tradgang.com/cgi-bin/ultimatebb.cgi?ubb=forum;f=24
FOC: http://www.tradgang.com/ashby/2008update1.pdf


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## TMan51 (Jan 25, 2004)

gjarcher said:


> All software will only get you in the ball park.


I have picked up a couple of programs over time, and they are fun to play with. On the otherhand, they cannot differentiate the variables associated with static/dynamic properties, and unless there's been a lot of advancements in the engineering end of archery in the last couple of years, are not likely to get there soon.

Bottom line, they might tell you a choice is bad, but they can't necessarily tell you wether it's good. The sad, but interesting part of arrow selection, is that each application is to some extent, unique. And the properties of aluminum, aluminum/carbon, and all of the variations in carbon construction, pretty much guarantee that we will always have several choices, because there's no "best one" out there. FOC is an even bigger black hole.


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## TAP (May 28, 2002)

TMan51 said:


> I have picked up a couple of programs over time, and they are fun to play with. On the otherhand, they cannot differentiate the variables associated with static/dynamic properties, and unless there's been a lot of advancements in the engineering end of archery in the last couple of years, are not likely to get there soon.
> 
> Bottom line, they might tell you a choice is bad, but they can't necessarily tell you wether it's good. The sad, but interesting part of arrow selection, is that each application is to some extent, unique. And the properties of aluminum, aluminum/carbon, and all of the variations in carbon construction, pretty much guarantee that we will always have several choices, because there's no "best one" out there. FOC is an even bigger black hole.


Nothing will ever be able to differentiate the difference between Static and Dynamic spine. My program TAP PRO i guarantee will get you the right arrow for your bow, things such as overall bow tune and shooting form are dynamics that is impossible to predict with software.

Spine and arrow selection is a very well researched and documented science. I agree that Carbons and Aluminums and even Hybrids all have their unique properties, but defection is deflection and for the purposes of getting an arrow that will have the proper flex for accurate shooting my software is already there. The alogorythm used in TAP is a proprietery calculation that I derived over MANY years of shooting and tuning.

FOC isn't so bad really. There is no magic number that is good for type X shooting. Keep in mind that the lower your FOC gets the more your groups will open at distance. Personally I try and keep my 3D arrows in the 8-10% range and hunting I like about 10-12% and Field I try and get into the 12-16% range.


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## Whitey375 (Mar 26, 2009)

Thanks for the input guys. So do is the general consensus that I could shoot a 29" Axis 300 with the 75 grain brass insert with a 150 grain broadhead? Or a 28.5" .400 spine Axis with the same insert and a 100 grain head? Btw, that would make both of them at 17%+ FOC.


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## Hit-em (Oct 3, 2002)

Does the Tap program take into consideration the type of cam your bow has when you feed in your bow parameters when figuring arrow spine ?


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## Whitey375 (Mar 26, 2009)

And where to buy said program?


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## TAP (May 28, 2002)

Hit-em said:


> Does the Tap program take into consideration the type of cam your bow has when you feed in your bow parameters when figuring arrow spine ?


TAP does not use the cam type for figuring spine as it uses the actual performance of the bow. Here's an example.....using charts or other software would have you select say a hard cam. Now usually by definition a hard cam is defined as a bow with an IBO over around 300 f/s. 

I never agreed with a bow that shoots say 310 and a bow shooting 330 needing the same arrow so that is why I derived a better algorythm about 10 years ago now. You can either select your bow out of the database, or you enter the known specs and with THIS information TAP will select arrows.


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## TAP (May 28, 2002)

Whitey375 said:


> And where to buy said program?


In my signature...


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## Hit-em (Oct 3, 2002)

TAP said:


> TAP does not use the cam type for figuring spine as it uses the actual performance of the bow. Here's an example.....using charts or other software would have you select say a hard cam. Now usually by definition a hard cam is defined as a bow with an IBO over around 300 f/s.
> 
> I never agreed with a bow that shoots say 310 and a bow shooting 330 needing the same arrow so that is why I derived a better algorythm about 10 years ago now. You can either select your bow out of the database, or you enter the known specs and with THIS information TAP will select arrows.


So the only way to get an accurate answer regarding spine is to have your bow chrono'd & feed all that info ie..bow specs...arrow specs ...to get the proper arrow for your set up.

As we know.. most bow manf's only give general ranges for IBO #'s & those can be way off ...

So to be assured of correct arrow spine we would need to get solid information on our set ups before entering those #'s into your program...


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## TAP (May 28, 2002)

Hit-em said:


> So the only way to get an accurate answer regarding spine is to have your bow chrono'd & feed all that info ie..bow specs...arrow specs ...to get the proper arrow for your set up.
> 
> As we know.. most bow manf's only give general ranges for IBO #'s & those can be way off ...
> 
> So to be assured of correct arrow spine we would need to get solid information on our set ups before entering those #'s into your program...


I dont think the MFG specs are that far off? Of course getting your own custom BPF from your own bow is the best, but like I stated....the database specs are usually fine for arrow selection.


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## UnlicenseDremel (Jul 7, 2011)

Any of these available for Iphone or Android?


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## weston2009 (Feb 13, 2009)

UnlicenseDremel said:


> Any of these available for Iphone or Android?


what he said


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