# Cutting off inches of arrow, the effect on spine?



## rattus58 (Jul 9, 2007)

rembrandt said:


> I will be cutting off around 2 inches of my new arrows when I get my Excel set up and ready to go. I am sure the effect to the spine will vary from one arrow make to another but having said that will the stiffening of the spine be all that much? Will it have to be taken into account before obtaining the arrows? In my PURE I shoot 28" arrows and with this new SAGE bow I'm shooting 31" arrows. I have too much in front of the riser to suit me. But, I'm open to info on what is best when I get the Excel set up. It will be strictly a target bow and I want to cut back on arrow weight........BTW, I have a 29" DL...


 Reducing the length of the arrow will stiffen the dynamic spine of the arrow... well arrows over 26" anyway... how much depends on the arrow. I'm a woody guy and I've used aluminum in the past but most of the aluminum will change 2-3 pounds per inch I think. Carbon and composites might be different. It's only going to make a difference if you're on the edge spinewise anyways... and it's easy to "fix" with a little weight up front.

Much Aloha... :beer:


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## rembrandt (Jan 17, 2004)

Thats good to know cause I'm gonna shorten my arrows with this new Excel bow. I feel like to get the speed and flatness I need for 3-D, I'm gonna need a lighter and shorter arrow.....


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## Viper1 (Aug 21, 2003)

Dave - 

2" can give you as much as 10# off in dynamic spine (make them as much as 10# stiffer). Before you cut anything, use the arrows the way they are. With the lighter weight, your draw length might increase a little more as well. Also remember, that if you go with a plunger on the Excel, you can adjust the dynamic spine at will. (Chapter 7  ). 

Viper1 out.


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## grantmac (May 31, 2007)

rembrandt said:


> Thats good to know cause I'm gonna shorten my arrows with this new Excel bow. I feel like to get the speed and flatness I need for 3-D, I'm gonna need a lighter and shorter arrow.....


Unless you are shooting 700-800 spine arrows then you will actually build a heavier arrow if you cut them, because you will have to add point-weight to tune them. Plus you will end-up with a longer point-on distance which is not a benefit for 3D. Most good 3D shooters who shoot categories which require a fixed anchor point are shooting as long arrows as possible, I've got a 28.5" draw and I shoot 32" arrows. If I could find some light 500-600 spine 34" long, I'd be in heaven.

-Grant


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## JParanee (Oct 13, 2009)

Start with full length bare shafts in a spine that should work cut a 1/4 inch at a time from the shaft till you get good flight . I like to stop a tad on the soft side . If you get down to an arrow that is to short for your draw then start again with a stiffer spine 

Like I said I like to stop on the tad soft side but I have been tuning this way for many years and as long as I do this I get excellent broadhead flight


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## Kayo (Mar 15, 2010)

I have a 27.5 " draw length with a excel 40# TT carbon/wood blackmax limbs. I cut my arrows to 28" to 29" depending on the weight of of the arrows ( 6.4 to 10gr/inch). Take a look at the Easton shaft calculator and play with it at different lengths/weight per inch arrows and tip weights. I can shoot 0.600 and 0.500 arrows depending on arrow/length/weight and tip weight.


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## rembrandt (Jan 17, 2004)

Well, it lookls like I have some work to do.....


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## AKRuss (Jan 10, 2003)

The old rule of thumb is for every inch you increase shaft length or every 35 grains you add to the point, you decrease dynamic spine by 5 pounds of draw weight. Adding weight to the rear of the shaft increases dynamic spine. Rules of thumb are truisms and generally correct. Bare shafting is the acid test.


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## Jake T (May 31, 2008)

AKRuss said:


> The old rule of thumb is for every inch you increase shaft length or every 35 grains you add to the point, you decrease dynamic spine by 5 pounds of draw weight. Adding weight to the rear of the shaft increases dynamic spine. Rules of thumb are truisms and generally correct. Bare shafting is the acid test.


is that true for carbon and aluminum too or just wood?


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## trapperDave (Mar 12, 2005)

carbons dont act like aluminum or wood when it comes to cuttin. start long, remove a quarter inch at a time


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