Author Topic: Spine wt. on arrows (Read 5233 times)

Ranger B · « **on:** December 10, 2008, 03:30:51 pm »

If you buy shafts and they say they have the spin on them I assume that the spine wt. is based on the 31" arrow I'm buying so if I cut them to 28" I just increased the spine wt. Is there a rule of thumb for how many #s you gain in spine wt. for an inch cut off an arrow?

Pat B · « **Reply #1 on:** December 10, 2008, 03:36:20 pm »

Jimmy, I believe the spine weight is based on a 28" arrow. For each inch over that subtract 5# and for each under that add 5#. Pat

TRACY · « **Reply #2 on:** December 10, 2008, 10:00:32 pm »

Exactly what Pat said.

Pappy · « **Reply #3 on:** December 11, 2008, 11:35:19 am »

What Pat and Tracy said.

Pappy

Mechslasher · « **Reply #4 on:** December 11, 2008, 11:47:38 am »

to further confuse you, the spine is actually measured at 26" for a 28" arrow. pat's right on with the length/spine calulation. you then have to take into account what type of bow you shoot as well as point weight to come up with the "right" spine for your setup.

Pappy · « **Reply #5 on:** December 12, 2008, 07:22:39 am »

Mechslasher,I have always been confused on that.My spine tester is 26 between the supports
so if I spind them it is at 26 but for a 28in. arrow,Right. If the arrow was actually 26 it would be about 10 lbs. heaver than the spine tester says and if it was 30 it would be about 10 lbs. lighter.
That is the way I have always done it but a little confussing.Then to make things more interesting if you have a regular wood arrow that flies good at a certain spine then go to shoots or Cain that all goes out the window,you can go much heaver on them.At least 10 or 15 lbs.it seems to me.

Pappy

TRACY · « **Reply #6 on:** December 12, 2008, 10:54:44 am »

Clear as mud isn't Pappy

Tracy

Mechslasher · « **Reply #7 on:** December 12, 2008, 11:21:47 am »

pappy, i'm guessing that when arrow maker's first set up a spine tester standard, 26" is what they went with. don't know why. any two pound weight will test the spine of an arrow. 1/2" of deflection equals 52# spine, or is it 51#.

here's my formula for guessing what spine arrow to start with:
-add 5# for every inch over 28" and subtract 5# for every inch under 28".
-subtract 5# for every 1/4" the bow is away from center cut.
-add 5# for every 25gr. over 125gr. for point weight, subtract 5# for every 25gr. under 125gr.

cane and shoots arrows are tapered, so the spine is calculated different for them. for tapered shoot or cane arrows, i subtract 5-10# spine. depending on how much taper they have. the taper is what makes cane arrows so forgiving because when the arrow leaves the string, it's closer to center than at full draw. this makes them much less critical of spine and release.

Pappy · « **Reply #8 on:** December 12, 2008, 12:18:45 pm »

Thanks that helps a lot,been doing it for years but still wasn't sure I was right,guess I was pretty close.That is about the way I have figured it except for the points.I knew heaver made them weaker just no guess how much.Thanks.

Pappy

markinengland · « **Reply #9 on:** December 20, 2008, 04:43:51 am »

If you do a search for the actual AMO standard for the spine rating of shafts this explained quite well.
This link should give you that information
http://www.archerysearch.com/publications/AmoStandards.pdf
The spine ratings given are for a standard arrow and bow set up comon at the time the standard was written. Obviously not evryone shoots a standard set up. Once you find out what spine rating works for your bow/string/arrow/loose then you know what spine to aim for in the future.
Mark in England

roofus · « **Reply #10 on:** December 21, 2008, 02:13:28 am »

I just found an arrow that works right with my bow than spine tested it and spine my shafts to that.
Here is a picture of my tester. It is ugly, very ugly but very simple and it works.
I shoot 28" arrows so I built it on the 26" span rule with a 2# weight.

[attachment deleted by admin]

George Tsoukalas · « **Reply #11 on:** December 21, 2008, 12:12:59 pm »

The supports are 26" but the readings are translated automatically for you for 28 inches back of point so that's really 28.75ish inches. It is confusing but it shouldn't be to us primitive types. Not because we have superior intellects but because most of us make our own shafts and a little judicious sanding in the middle can do wonders for arrow tuning.

Jawge

Shooter_G22 · « **Reply #12 on:** December 31, 2008, 02:07:26 am »

ok people,

i have yet to make an arrow spine tester and i have every intintion to make one soon, soo with that being said i know im going to have a boot full of questions later... but for know i jsut wanted to ask this one..

if im making arrows out of pine wood drilled through a dowel cutter and then compressed through a heat compression block... would i then start to cut to the desired lenght and then start to spine??? AND separate by wieght??? ok?? here is my real question... once i get my jigs and sytem all set up i know im going to want to do up some real nice arrow sets... but if im crest dipping and lacquer coating wouldnt this effect the spine also.. lets say i do the common 3 dips of lacquer would i have to re check the spine again after the lacquer dries up or will the spine test not be affected by the clear coat...

and if it is when would you spine and separtate??? after the coats of clear i would want to waste clear coats especially if im going to be sanding in the middle to get the arrows even???
any help or experaince here?

?

thanks...

Primitive Archer