Spine calculating programs

[DylanK]

Just wondering how accurate these programs are? I was using the OnTarget2 software for archers program.  It works out that i need a .400 spine for 225gr upfront and 31"long shaft for a 40# bow.

Does this seem about right?

Thanks

Dylan

[dino]

Seems a bit stiff at first but I think that is pretty close for starters.  You might have to adjust point weight for fine tuning. dino

[DylanK]

I dont know wether to use the program or the old rule of thumb that i learned not long ago.  28/spine so 28/.500 = 56. every 35gr of weight up front despines 5# same with every inch. so for 100gr insert and 125 grain point, it despines it about 10# which makes it 46#. Then since my draw is 28" my arrow would be around 29"so that make the arrow good for a 41# bow.

the program says this is extremely weak. i duno what to use.
Does this make sense lol.

[Soilarch]

For compound shooters those programs are usually spot on.   Don't know how that translates to traditional stuff.   I'd say at the worst they'll be real close.

[DylanK]

ttt

[JRY309]

You may be able to figure out some thing close,but you have the human factor that would be difficult to calculate.Every shooter is different,what works for one may not work for someone else.Carbon arrows are spined at 28",I don't know any way to calculate dynamic spine which I believe you are asking other then shooting them and see how they react to your shooting.There would be alot of variables involved,trad bows just are not that mechanical in my opinion.

[WESTBROOK]

Thats pretty stiff, I think. I wood go with a .500 or CX heritage 150 (.487). My Shrew is #53 @ 29", I shoot a 31" CX 150 with a 50g insert and 175g point, 585g total weight.

Eric

[DylanK]

i guess i will buy one .500 and one .400 spine arrow and see what works the best.  thankyou all