Arrow Spine

Choctaw-Brave · 01-20-2005, 05:33 AM

Can Someone Explain What Arrow Spine Is?

Sniper151 · 01-20-2005, 07:05 AM

Choctaw, Arrow spine is the amount of flex or bend in an arrow at the center point of the shaft. This is usually calculated using a 28" arrow. The arrow is supported on each end and then pressure or a weight is applied to the center. The amount the arrow sags or bends in the center is considered the spine. Using the same amount of weight or pressure on the center point the more the arrow sags the weaker the arrow spine and the less flex the stiffer the spine. This gives you a basic idea on the flex of the arrow with all the components added. You can reduce the spine of an arrow by changing components. A heavier tip or broadhead will weaken the spine. Installation of extended nocks like the Beiter will stiffen the spine. This is why an arrow selection chart will ask many questions as type of cam, draw weight and length of draw. Each of these items have an impact on the static weight and excelleration of the arrow when released. The harder the cams, length or tip weight will determine how much flex there will be at the center of the arrow upon release.

BobCo19-65 · 01-20-2005, 07:36 AM

These days the term arrow spine refers to deflection of the arrow as is calcualted as above. However, the spine of the arrow is actually the weakest part of the arrow as compared to its deflextion as it is spun on its axis. Finding the arrows spine especially when using cedar arrows on stick bows is very important. Keeping the spine aligned with the cock feather is very important on stick bows. Even with my compound, I mark and align the spine of the arrow, so that they come off the bow consistant. You will find that aluminums have the most consistant spine and wooden arrow the least. Carbon would be somewhere in the middle.

Choctaw-Brave · 01-21-2005, 07:17 AM

How Do You Go About Finding And Marking The Spine? Do You Find The Weakest Spot By Rotating Arrrow While Applying Pressure? Then Set Your Cock Feather In Line With That Point? Please Elaborate. Thanks

BobCo19-65 · 01-21-2005, 09:24 AM

Wood arrows are about the easiest because you can just float them. Some people also cork and floats aluminums and carbons. Some people use three roller bearings, one on each end of the arrow and one in the exact middle, then push down in the center bearing, this takes practice, but will get you close. I use spine tester, which is about the most accurate. But remember that on aluminums, you are basically spliting hairs.