Archery Talk Forum banner

1 - 4 of 4 Posts

·
Registered
Joined
·
1,832 Posts
Discussion Starter #1
Can someone explain spine deflection to me, is better to have a .500 spine deflection, or a .340? Basically a smaller or larger number spine deflection.
 

·
(aka lug nut)
Joined
·
49,655 Posts
Can someone explain spine deflection to me, is better to have a .500 spine deflection, or a .340? Basically a smaller or larger number spine deflection.


Gotta match the total arrow stiffness
to the total energy produced by your bow.



Kinda like asking is it better to have 1000 horsepower
or is it better to have 5 horsepower?


Well, it depends.

If we are talking your gasoline lawnmower,
then 1000 horsepower is probably not a good idea.


If we are talking a jet engine for a 747,
then 5 horsepower is also not a good idea.



The stiffness rating of the arrow alone is not enough information.



If we are talking about a 70 lb draw weight bow,
if we are talking about a 29-inch draw length
if we are talking about a 100 grain field point or broadhead
if we are talking about a 30-inch or 29-inch arrow....

then the 0.340 stiffness rating arrow is probably a good choice.


Ideally,
need to know the cam system.

Is this a wheel cam system...
is this a binary cam system...
is this the Hoyt Spiral cam system...
is this a Mathews single cam system...


the cam system makes a difference
because each cam system style produces a different amount of energy.



So,
need to know what bow, and what cam system.


Need to know the draw weight of the bow.


Need to know the draw length setting of the bow.


Need to know if we are talking target point
or broadheads....broadheads are VERY picky about the correct
total stiffness of the arrow.


Need to know the weight of the target point
or
the weight of the broadhead.



Need to know the size and brand of vanes.
YUP.

Longer vanes weigh more.
More weight on the back end of the arrow makes the arrow
BEHAVE stiffer.


4-inch vanes will make an arrow BEHAVE stiffer.
2-inch Blazers will make an arrow BEHAVE a bit weaker.


So,
do you want the 1000 horsepower motor
or would you like the 5 horsepower motor?


Need to know a little bit more info.
 

·
Cato
Joined
·
4,093 Posts
Spine and deflection are different ways of measuring the same thing; stiffness of the shaft, or lack thereof.

In the old days, wood arrows were put on a spine tester, which suspended the shafts on a 26" distance, and hung a weight in the middle. The shafts were then grouped according to how far the shaft bent. Generally, the spine tester was set to indicate the poundage of bow appropriate for the amount of bend. For example, a 50 to 55 spine, theoretically would shoot out of a 50# to 55# bow, if the shafts were cut slightly over 26". Of course adjustments had to be made for longer shafts. And then when high tech bows came along, the class no longer was an indication of what would shoot out of your bow, you just had to experiment with your draw length, type of bow, string material, head weight, etc.

Deflection basically measures the same thing. The deflection # is the amount, in inches I believe, that a shaft bends when put on a spine tester suspended at 28" apart. So the higher the number, the more the shaft is bending, and therefore the weaker the shaft is. A 300 deflection is stiffer than a 400 etc.

HOpe that helps.

Cato
 
1 - 4 of 4 Posts
Top