Why is the Balance Point important and how to find it2020-06-23T17:59:13-05:00

This is the second step in what I call “the arrow maker’s conundrum,.

You may recall that I believe there are for (sometimes competing factors within a set of 12 arrows which must be found to harmonize with each other and fall within a certain range to find the “sweet spot”.  Now that we have briefly discussed arrow length, it is time to see how this naturally leads us to finding the balance point of an arrow and learning why this is important for a traditional archer.

Arrow Length

Arrow Weight

Static Spine

Arrow Balance

THE EQUATION FOR CALCULATING THE BALANCE POINT OF AN ARROW.

WHEN WE KNOW THE TRUE LENGTH OF AN ARROW, WE CAN FIND THE BALANCE POINT.

The balance point of an arrow, sometimes simply referred to as F.O.C. (forward of center) is another of the four important factors we need to match to find out “sweet spot” come from this.  That is why it is an important step.

When we know the length, we can find the center of the arrow’s length.  In this case, we have an arrow exactly 32 inches long.  This means our “arrow center” is 16 inches from the crotch of the nock.

Now we can place this arrow on a straight edge and mark the balance point of the arrow.  I use a sharpie because the mark is easily removed with finger nail polish remover.  As you can see in the top photo to the right, the balance point of this arrow occurs at 19.875 inches from the crotch of the nock.

Once we know both of these points, we can calculate the F O C (forward of center) of the arrow.  These F.O.C. balance points don’t have to match each other exactly for bamboo arrows. but they do need to fall within a certain range.  For my quiver, if the arrow is heavier a bit heavier, the balance point should be about 14% – 17% forward of the center of the arrow (F.O.C.)  If the arrow is a bit lighter, it can be a lower balance point to be 14% – 15% F.O.C.

There is a simple calculation for finding the F.O.C. of the arrow when we know both the balance point of the arrow, and the center of the arrow’s length.  In this example, it will look something like this:

  • The balance point of this arrow (19.875 inches) minus the center of the arrow (16 inches) = 3.875 inches.
  • If we take this difference (3.875 inches) and divide it by the arrow length (32 inches) this number is .12109.
  • If we multiply this number by 100 (.12109 X 100) we then have our F.O.C. for THIS arrow.
  • It is slightly over 12%.

Hmmmmm  that is a bit lighter than I would like.  I already suspect that this is an arrow which will need a slightly heavier head.  Since most bamboo arrows usually shoot well with a 125 grain head or a 145 grain head.  I already know that I will put a 145 grain head on this arrow…..MAYBE.  Remember, there are 4 competing factors in that sweet spot!  We have other information to gather first.

WHEN WE KNOW THE TRUE LENGTH OF AN ARROW, WE CAN FIND THE BALANCE POINT.

The balance point is one of the 4 important steps to having highly dependable arrows which group into that teacup if our form is good.  These 4 steps (which might possibly conflict with each other) do require some judgement.  After all, anyone can make an arrow which will hit the bull’s eye.  But it takes skill to make a matching set of 12 wooden arrow which will fit into a teacup at 20 yards.

Balance point and length are a function of each other, and thus have to be considered jointly.  For instance, If this arrow were shortened by just 1 inch, the balance point will shift as well as the center of the arrow.  In this case, if the balance point of the arrow is now 20.375, but the arrow is now 31 inches long, the new FOC becomes very nearly 15.75%.

Imagine adding a heavier head to this shortened arrow.  This will push the FOC up even more.  To have a high FOC is not necessarily good or bad.  The same is true for a low FOC.  I personally find that arrows above 17% and those below 13% FOC do not group as tightly as those that are in the 15% – 16% FOC range for my arrows shot from my bow.  Possibly your experience may be different.

Lastly, when you buy a set of arrow and the FOC values vary beyond 2% within the group, there may be a problem…DEPENDING.  Depending on whether the spines and weights are closely aligned or not.  I match the arrows in my quiver to be within 1 pound of static spine within all 12 arrows.  I also match them to weigh within 20 grains from the heaviest arrow to the lightest arrow within the set of 12 arrows.  Heavier arrows fly “stiffer” than lighter arrows.  The dynamic spine is stronger.  AS AN ARROW MAKER, MY TWO GOALS ARE NOW…AND ALWAYS WILL BE TO MAKE AN EXTREMELY TOUGH SET OF ARROWS WHICH WILL GROUP INTO A TEACUP AT 20 YARDS BECAUSE THEY MATCH AND ARE PREDICTABLE IN FLIGHT.

If I do this, a set of matching arrows with a 13% FOC is just as dependable as a set of arrows with a 16% FOC…FOR GROUPING TIGHTLY.  However you may have other priorities in mind.  I can make them any way you want, but just so you know…they will ALWAYS be within 1% – 2% FOC if I make them unless you request otherwise.

Balance point and length are a function of each other, and thus have to be considered jointly.  For instance, If this arrow were shortened by just 1 inch, the balance point will shift as well as the center of the arrow.  In this case, if the balance point of the arrow is now 20.375, but the arrow is now 31 inches long, the new FOC becomes very nearly 15.75%.

Imagine adding a heavier head to this shortened arrow.  This will push the FOC up even more.  To have a high FOC is not necessarily good or bad.  The same is true for a low FOC.  I personally find that arrows above 17% and those below 13% FOC do not group as tightly as those that are in the 15% – 16% FOC range for my arrows shot from my bow.  Possibly your experience may be different.

Lastly, when you buy a set of arrow and the FOC values vary beyond 2% within the group, there may be a problem…DEPENDING.  Depending on whether the spines and weights are closely aligned or not.  I match the arrows in my quiver to be within 1 pound of static spine within all 12 arrows.  I also match them to weigh within 20 grains from the heaviest arrow to the lightest arrow within the set of 12 arrows.  Heavier arrows fly “stiffer” than lighter arrows.  The dynamic spine is stronger.  AS AN ARROW MAKER, MY TWO GOALS ARE NOW…AND ALWAYS WILL BE TO MAKE AN EXTREMELY TOUGH SET OF ARROWS WHICH WILL GROUP INTO A TEACUP AT 20 YARDS BECAUSE THEY MATCH AND ARE PREDICTABLE IN FLIGHT.

If I do this, a set of matching arrows with a 13% FOC is just as dependable as a set of arrows with a 16% FOC…FOR GROUPING TIGHTLY.  However you may have other priorities in mind.  I can make them any way you want, but just so you know…they will ALWAYS be within 1% – 2% FOC if I make them unless you request otherwise.