Dynamic Spine calculator. .NEW DOWNLOAD AVAILABLE

[Rob DiStefano]

Originally posted by snag:
I hope I don't sound like I don't believe your results Rob. I am just confused as to how this can be when I get such different results. Yep, I'm confused...not the first time!     :confused:     But as long as you are getting good arra flight and I am happy with mine that's all that counts.

as i've said b4, there's more to good arra flight than physically measured criteria.  it took me a long time and too much wasted money to for me to be a believer, but actions speak louder than words.  

fwiw, i can't get beman 340 or 400 spine carbons
(29", 350 up front) to bareshaft straight (right tailing stiff) without resorting to my bag of form "tricks".  just moving the 350gr insert/adapter/point over to the 500's makes them puppies fly on rails for me.

in my former life, as a looong time "serious" target archer, shaft selection was incredibly far more critical (fingers recurve, non-olympic freestyle) as distances ranged from 10 to 100 yards and the upright stance form, with under the chin anchor, dictated different bow and arra tweaks to get the missiles to group very well at all marks.  for the most part, those arras were bareshafts, touting only 1.7" spin wings and a low 9-13% foc (we all thought that was heavy foc, when compared to the standard 7% foc).  if i only knew then what i know now ....

[Mark-R]

This tool has been helpful to me.  Im just getting back into trad. after many years w/ compounds.  Just from tinkering w/ numbers, it sounds like a person could shoot GT 3555 AND 5575 out of the same bow just by adjusting point weights. For me, it sounds like a GT 5575 would be better because I want the extra weight.

[jrchambers]

sorry for the double.  i put a 300 carbon for a ad heavy and i ended up at 50.1 shaft and 50.1 with a super shrew. i guessed they were about a quarter to three eighths off center.

[Mark-R]

Sorry if I sound dumb, but what is ads.  Are you talking about arrow dynamic spine?

[Rob DiStefano]

Originally posted by Mark-R:
Sorry if I sound dumb, but what is ads.  Are you talking about arrow dynamic spine?

i believe the reference to "ads" is for arrow dynamic tapered carbon shafts.

[leatherneck]

Sorry, I was refering to my Arrow Dynamic shafts. Any help on these?

[wingnut]

No Help on Arrow Dynamics yet.  Ted is sending me an assorted cross section of the shafts.  I'm going to do the spine testing and should have some good data in about a week.

Mike

[leatherneck]

Thanks Mike. If ya would, could ya PM me the results?

[wingnut]

I'll publish them here and pass them on to Ted Fry at Raptor.

Mike

[metsastaja]

any one using the offset caused by the plate on shelf. ie if your bow is center cut and you have a 1/16" plate do you put that in the calculator as +1/16. asking cause those numbers make big difference.

[wingnut]

Les,

I used the actual cut of the riser and mine and now 3 others have tuned right up.

Mike

[metsastaja]

I am adding in the plate on mine. two bow have shown to be right on. and I am shooting better then ever.  I have left a couple posts where Stu hangs out. Hoping to get a response from the author. Building out center cut with plate is one of the ways of tuning.

[daveycrockett]

? Do you add the weight of your nock and wrap as nock end weight? Then use insert and point as point weight?

[clayton95]

Just wanted to ad my thoughts about how the chart worked for me.  I am in the same boat as Rob with shooting full length beman 340's with 385 grains up front.  The chart says that I need to drop point weight down to around 200 to get in the ball park.  My draw is a true 31 inches and pulling 66 pounds at that length. It works well with feathers and bare shaft.

[Oregon Okie]

How are you guys measuring the side plate? Site down the string / some kind of mini plumb bob? Measure the riser itself. This number seems to make such a difference that I wanted some good ideas for measuring it accurately.
thanks

[SELFBOW19953]

From what I see, this calculator disagrees with the easton spine selector chart by huge amounts.  

For instance, I'm trying to set up a 52" 50@28 Red Wing Hunter for turkey.  I draw 28". The right side number is 48.0.  I have been trying 2013 shafts cut to 28.5" with feathers.  The calculator says I need to shoot 175 grain points to get 47.5 on the left side. I really hadn't planned on using 175 gr points for turkey.

Am I doing something wrong??

However the Easton chart says that with only a 75 grain point I need to be using 2018 shafts (the chart max's at 150 gr).

There's a hoop of difference between the weight and spine of a 2013 and a 2018.

Normally, I don't bare shaft my bows.  I try 2 or 3 different spines, find the on that flies best and tweak it-point weight, fletching size, brace height, etc.  When I get consistent, accurate arrow flight, I'm ready to go hunting.

[wingnut]

I believe you will find the dynamic spine calc to be closer to reality then easton.

Theres is mostly for compound bows even though they have a recurve section.

Mike

[Rob DiStefano]

i've found, for the very most part, that the easton shaft charts, as they apply to trad bows for alum, carb/alum, and carbon, aren't even close in too many instances, and for a number of archers (not just me).

[James Wrenn]

With Stu's calculator you have more input for adjustments than Easton's.It can get closer.Easton't assumes ff strings and bows cut past center.It also assumes if you put in an arrow 30" long you are pulling 29" on draw ect.That can't be changed so it will not be as close if you are shooting outside the norm.With the other being able to set draw length and use an arrow of any length pluse the change in centershot will fine tune things much more.

Most of my bows are cut past center.I use skinny strings and with the longbow selected on Easton's arrow selector I have no problem shooting arrows they recomend.If I choose recurve they will give me a stiffer arrow than I need.Both Stu's and Easton's put me in the same range when I use the longbow seleaction.Close enough normal point weights will work. jmo

[snag]

I have some 85#-90# tapered POC shafts that I pulled out and wondered if 250gr tips would work. I plugged in the numbers and found with 28.5"bop and 260gr tips (100gr.adapter w/ 160gr. field point) the numbers came up 62.3 and 62.8. So cut a couple down to 29"bop and gave them a bareshaft try...a little weak, went to 28.5" and they came in about 1"-2" weak! Perfect after fletching. Love this chart!