Dynamic Spine Calculator vs. Arrow Selection Chart

[Mike L.]

I just discovered Stu Miller's Dynamic Spine Calculator.  As is often the case with a new discovery, it opens up more questions than answers for me.  Using the dynamic spine calculator for my Black Widow PL Longbow showed that I have been using arrows that are at least 10-20 lbs too heavy for my bow.  How is this possible if I have followed the Arrow selection chart   every time?  Also, does anybody know which bow I should use on there for a super shrew 62" 51@29?  Or should I just put generic R/D?  Not sure how the forward grip will affect the results.

[Night Wing]

Some bow designs like a stiff arrow while other bow designs don't.

[reddogge]

Some bows have a wide tolerance of spine. I once killed the largest doe I've ever killed shooting a 30" 2117 arrow out of a 45# Bear Kodiak Hunter. Do the math on that one.

[JamesKerr]

The closer a bow is to center shot the more arrows it will shoot. My current arrows are about 10# underspined according to Stu's calculator and charts but they fly great for me. The only thing that matters is that they work for you.

[Sam McMichael]

Remember that all guides are just that - guides but nothing carved in stone. Shoot what gives the best performance out of your individual bow and what gives you the greatest confidence. I have several bows that like arrows that don't correspond to the charts. As precise as we sometimes like to be, archery is not rocket surgery.

[Jim Wright]

What Sam said, I commonly end up getting perfect flight especially with carbons not even close to what the charts indicate. Some bows are very spine tolerant and when things like the length and weight of the insert/inserts, shooting form and technique which can vary greatly between shooters are factored in, you can end up shooting a spine shaft that's way off what's suggested.

[snag]

The older charts were developed for bows with shelves NOT cut to center or past center. More modern day bows can shoot stiffer arrows well. I shoot a 55# recurve that has a shelf cut to -3/16 and it loves 80/85's. No chart I've seen would recommend this.

[Flying Dutchman]

The arrow selection card is much more general...it says nothing about center-cut and string count for example. The only differentation is poundage,drawlenght, longbow or recurve. Stu goes much deeper.  I tested  a lot of bows with Stu's calculator.  Meaning: make the arrows acording  to Stu's calculator and testing it by barshafting. Most of the time Stu is spot-on.

But remember: garbage in means garbage out!

[Rob DiStefano]

ALL "arrow/spine calculators" MUST be taken with a full box of salt.  do not despair if any of these devices don't appear to work well for you.  they are ALL guidelines of sorts and it pays to treat them as such.  and if such software does appear to work well, good for you.

if anyone has a problem with a software arrow/spine calculator's operations or functions, please take your questions back to the software creator and get the scoop from the horse's mouth.

i will add, as usual, there is no substitute for personal testing when it comes to archery tackle - bows, arrows, bowstrings.  there is SO much uniqueness to add to the bow and arrow selection process, and that starts with you, the archer.

[metsastaja]

Mike if you have not done so yet download the instructions and read them.  Center cut and string selection can make a big difference.  

prior to 2011 shrew bows were cut -1/8. they are now cut to 0.

Here is a link to bow center cuts compiled by TG members and bowyers. it is a pdf you can download  

  http://www.heilakka.com/Bowcentercut.pdf

[Mike L.]

Thanks for the encouragement.  I was getting a little bummed about having spent so damn much on arrows through the years and finding out none of them were correct.  Then I read the tuning section on O.L. Adcock's webpage.  Awesome information.  I read about FOC, and it looks like those heavy spines are exactly what I want.  I was wondering why so many on here used such heavy points.  I'm really excited to try the string idea too.  I'm waiting for my supplies to learn how to make strings.

[Mike L.]

Also, does anyone have any suggestions for how to enter my 62" Super shrew into the spine calculator?