2007 DeMairni Voodoo BESR 32/29

ID: 362

Phyiscal Metrics









Scale Weight

Scale weight, opposed to stated weight, is the actual weight of the bat. That is, we put the bat on a kitchen scale and weigh it like a bag of rice. Bats almost always weigh more than their stated weight. When hitting a bat, scale weight doesn’t matter much (neither does stated weight). What matters is the swing weight or Mass Moment of Inertia (MOI). Scale weight, as is measured here, is used to calculate MOI. That’s its only value.

Pendulum Period

The Pendulum Period measures the amount of time it takes for a bat to swing from side to side while hanging on a frictionless pivot. Functionally, the number doesn’t mean much. But, it is vital to calcuate the MOI. In fact, the pendulum period is the most important factor in determining, mathmatically, how hard it is to swing a bat.

Balance Point

The balance point is the center of mass of the bat. It is the point along the bat where the bat balances. It is NOT the same as the swing weight but it is used to help calculate it. It is measured as the distance from the knob to the balance point.

Pivot To Knob Distance

To get an accurate measuremenet of a bats swing weight, we must know the distance between the place where the bat was pivoting and the end of the knob. This is the Pivot to knob distance and is used to help measure the swing weight. There is no non-mathmatical value in this number.

Swing Weight at 6 Inches

The industry uses 6 inches from the knob as the Pivot point to measure a bat’s swing weight. During an actual swing, though, it is very unlikely that a bat will rotate around a pivot at 6 inches from the knob. The true pivot is swing dependent, changes throughout the swing and is more than likely off the bat towards the hands. This gives the MOI at 6-inches metric questionable usefulness.

Swing Weight at Pivot

The swing weight measured at the pivot is not a practially useful metric. This is calculated so we can find the MOI (swing weight) at other points, like 6 inches or at the balance point, along the bat.

Swing Weight at Balance Point

The swing weight calcluated at the balance point of the bat also does not have any practical useage. However, it is used to help calculate the swing weight at the 6-inch mark. It is a measurement of how difficult it is to swing a bat around a pivot placed at the bat’s balance point.

Center of Percussion

The Center of Percussion is a location on the bat (measured from the knob) where vibrations meet in some sort of synergistic fashion such that the vibrations are cancelled out. Some consider this to be the sweet spot, as the bat feels and often sounds the best when hit there. However, it is most definitley not always also the sweet spot as sound and vibrational feel of bat are required to be placed where the bat’s material also happens to have the greatest trampoline effect.

Between Balance and Pivot

The distnace between the balance point and pivot point of a bat are used to help calculate the swing weight. The number has no non-mathmatical practical value.