Arrow Spine Calculator

[onemississipp]

* Sheet is online*   http://onemississipp.googlepages.com/spineweight.htm

I was building a spread sheet that one just "plugs" the length of a shaft into and it will do the math to give you spine weight at given deflections.

Well it confused me, I thought the longer you shaft was the weaker the spine would be at a given deflection.

Anyway here is what happened:

26" shaft at 0.515" deflection would be 50.49lbs
27" shaft at 0.515" deflection would be 52.43lbs
28" shaft at 0.515" deflection would be 54.37lbs
29" shaft at 0.515" deflection would be 56.31lbs
30" shaft at 0.515" deflection would be 58.25lbs
31" shaft at 0.515" deflection would be 60.19lbs

The Math is correct at shaft length divided by deflection = spine weight.

Where did I mess up?

[onemississipp]

I just figured it out....the 2lbs pushing in the deflection would push it further if the shaft being equal size but longer in length...

Sorry guys

I'll beat myself later!!!

[onemississipp]

Here it is in PDF it has arrow lengths from 26" to 31.5" and deflections from 0.100 increasing by 0.005 to 1.475.

 http://onemississipp.googlepages.com/spineweight.pdf

[Killdeer]

You have obviously been gifted with far more time than I.  :eek:

[onemississipp]

If anyone would like different lengths just let me know...OR a copy of the excel sheet where all you have to do is put in your shaft length and it will do the math again just let me know....

[onemississipp]

There is a link to the chart where you can adjust it to any length shaft, just change the shaft length number to whatever you like...26.75, 32.25, ect.......

    http://onemississipp.googlepages.com/spineweight.htm  

This way you can make a spine tester the length of the shafts you shoot.

[joebuck]

Dustin, thats impressive...I have an old Nickerson Dial Spine tester ( IMO best ever made). My bow loves a 230 deflection. or 110#-115# woodie which is close to your chart. Good work...thanks for the chart...Now if your good, how does this chart relate to parallel, single taper or barrel taper?

[onemississipp]

Good lord Joebuck!!!!!!

You just blew my mind with that "Now if your good, how does this chart relate to parallel, singer taper or barrel taper?"

I'm sad to say I don't know. I'm just beginning in the art of arrow making..

Not even sure how one would calculate that..

On a side note my last name is Nickerson....

[onemississipp]

Got any pics of your spine tester??

I'm thinking of making a spine tester that can be adjusted from 26" out to about 31"....some day even electronic, so you place the shaft press a button and watch the spine weight appear.

[stringstretcher]

I must be missing something, the chart will not show up for me

[joebuck]

Cetainly...it's in rough shape since my Alaskan Bowhunting friend used it for his Grizzly Stick protypes    

One thing to add about deflection.. Most arrow spine testers work off 26" with a 2#. So most( probably all) wood arrow manufactures spine or "spline " their arrows that way. One only needs to know what his Deflection is at 26"...then add #10 for every inch of finished arrow..Now..  :D  .thats my little rule of thumb...In short I think your 26" page is all one would need...Some people add another #10 for Fast flight, or #5 for fingers or #5 for radical limbs and sorts...  this is my Nickerson Chart...
.870-.999       25#
.745-.870       30#
.650-.745       35#
.580-.650       40#
.520-.580       45#
.470-.520       50#
.430-.470       55#
.395-.430       60#
.370-.395       65#
.353-.370       70#
.340-.353       75#
.330-.340       80#
.330-.340       85#
.323-.330       90#
.310-.316       95#

[joebuck]

If you are ever in Oxford, drop by..I been know to have some Tradgang people drop by and put me to work on their equipment!!!!

The parallel, single or barrel( double) taper is sort of tricky but look at it this way.. If you take weight off the nock or point then your barrel will be stiffer...you could use less spline...or more for barrel....How much more...it varies.. a matched set of barrel taper woddies to 2# and 5 grains is a work of beauty...........damn I miss those Supeceders..or Sam Salem at Mohawk Arrows

[onemississipp]

Opps sorry strinstretcher, you may have been after the pdf file, I was able you place the chart online, so you could change the length yourself.

I'll put the pdf back up.

[onemississipp]

Thanks for your offer, I may just stop by sometime.

I'm just beginning my addiction in traditional archery.

So far I have made 2 self bows and one river cane arrow. I have bought a couple dozen arrows but feel the need to make my own.

You will probably see more of me and my post, as I'm almost finished with a spine tester and plan on doing a "how to" for it.

[joebuck]

When I shot woodies, I always would give the vendor my prefered deflection @ 26" and lenght of BOP...To create a deflection chart past 26" would be non standard...IMO>>...Your chart compared to the Nickerson suggests a little heavier shaft in #'s...But I rather have a heavier shaft because I can always increase my BH weight.

[joebuck]

A spine tester would be real easy to make based off a dial caliber..basically you are just dropping a 2# weight on middle of shaft and reading how far it pushes the needle of the caliber down in 1000th of inches.....what would be cool is to have an electronic scale that measured in 1000/inches and place on a table  then place center of arrow on top..ooooopppps  I better quit...this sounds like an invention

[onemississipp]

According to what I have the nickerson chart you have uses a 30" shaft for the 95# mark....


My chart may need some work...I'll start comparing charts and see what happens

[onemississipp]

That's along the same lines as what I was thinking, only you dont see the measurments and all just the spine weight..

[joebuck]

It's 26"..

[onemississipp]

Thanks Joe for posting your numbers on your chart, I'll start gathering more data and hopefully improve my chart.