point weight/arrow spine
09-25-2002, 09:09 PM
#2
Nontypical Buck
Join Date: Feb 2003
Location: Oh USA
Posts: 1,584
RE: point weight/arrow spine
Increasing point weight will weaken spine. I don't think decreasing point weight will compensate for an arrow that's underspined. If you're talking broadheads, too little FOC will cause problems. I haven't seen too much problem with low FOC with field points, at normal 3D distances. Longer range shooting, which I don't do, may present problems.
Phil.
Phil.
09-26-2002, 06:20 AM
#3
Join Date: Feb 2003
Location: Fort Hood Texas USA
Posts: 529
RE: point weight/arrow spine
an arrow leaving the rest has to PUSH the tip (weather it is a FP or BH). Pushing a 75 gr point to 250 fps requires less force than pushing a 125 gr point to 250 fps. When the arrow is slung forward it bends, a heavy point on the front will make it bend bore than a lighter point. So if you have an arrow that has a weak spine, to some degree, you can compensate by going to a lighter point.
AH
AH
09-26-2002, 07:00 AM
#4
Join Date: Feb 2003
Location: Florence AL USA
Posts: 53
RE: point weight/arrow spine
A good rule of thumb is that every 20 grains of point weight equals 3 to 4 pounds of spine. By that, I mean that if an arrow is properly spined at 64 pounds with a 100 grain tip, if you change to a 125 tip the bow will need to be turned down to around 60 pounds for the arrow to regain the same stiffness. That's a pretty significant change in spine.
On the other hand, it's interesting to note that a point weight change of 25 grains means VERY LITTLE in terms of the overall weight of the arrow. For a 400 grain total arrow weight, 20 grains represents only about 5% of the total, which dictates Kinetic Energy. What does this mean? Point weight adjustments are mainly intended to help achieve proper arrow spine, NOT to increase the "hitting power" or penetration of the arrow.
On the other hand, it's interesting to note that a point weight change of 25 grains means VERY LITTLE in terms of the overall weight of the arrow. For a 400 grain total arrow weight, 20 grains represents only about 5% of the total, which dictates Kinetic Energy. What does this mean? Point weight adjustments are mainly intended to help achieve proper arrow spine, NOT to increase the "hitting power" or penetration of the arrow.
09-26-2002, 02:54 PM
#6
Join Date: Feb 2003
Location: Florence AL USA
Posts: 53
RE: point weight/arrow spine
Now that I think about it, I guess it would change dependent upon ARROW properties. The number I used was derived from an Easton chart a few years ago (you just look at the draw weights in the 100 grain column and compare to the 125 column right beside it.) I just looked at their latest and greatest selection chart in the 2002-2003 Bowhunting Guide, and it simply says "Add 3 lbs for point weights over 100 grains".
I could see where an arrow of stiff carbon construction wouldn't be as sensitive to point weight change as compared to a small aluminum.
So, my "rule of thumb" depends on the thumb, I guess...
I could see where an arrow of stiff carbon construction wouldn't be as sensitive to point weight change as compared to a small aluminum.
So, my "rule of thumb" depends on the thumb, I guess...
