Posted by: ray porco (rporco@verizon.net) on Wed Jul 27 20:03:38 2005

The first word in this thread title is “Confusion”, with which I agree wholeheartedly.
I have numerous disputes and questions for Jack and Dr. Kettering. Like it or not, I will list them numerically if either of you care to address them.

1. Jack says, “…, I have read test results from a number of bat companies that have changed my mind. These tests prove that forces applied by the hands to the bat handle at contact have no effect on how hard a ball is hit.”

The tests may have changed your mind, but I (maybe we) would like to determine for myself/ourselves. Could you please provide references, and share your proof?

Second, if you truly believe “…that forces applied by the hands to the bat handle at contact have no effect…” then why is most of your hitting theory based on what you term, “hand torque”?

2. Jack, you are not comparing apples to oranges when you compare “forces applied by the hands” with “how tightly you grip the bat”. I can apply force to a bat with a tight or loose grip, and I can grip a bat tightly or loosely without applying force (driving force, which is what I believe you were referring to). What is your point about, how much force you can apply to the bat with your hands or how loose or tight you grip the bat?

3. The first sentence (question) , first paragraph at the link Jack provided to one of Dr. Kettering’s webpages, asks, “Should you grip the bat handle as hard as you can, or loosely as you swing?”

Before I would answer that, I would ask, at what point in the swing? Meaning, does my grip pressure have to be constant throughout the swing?

4. The second question is, “Does gripping the bat harder make the ball come off the bat faster?”

And before I would answer that , I would ask, while swinging the bat at a pitched ball or holding the bat still while a ball is pitched at the bat?

5. Evidence #1: ball rebound speed from free and clamped bats. Kettering against.
Kettering’s quote, “After impact from the ball the bat is completely free to translate (swing away) and rotate about its center-of-mass (or a compromise between the CM and the pivot point). This "recoil" of the bat is significant because conservation of momentum says that any post-impact velocity of the bat changes the post-impact velocity of the ball. For the clamped bat, the entire handle of the bat was rigidly clamped in a vise so that the bat could flex or bend, but could not rotate or recoil after impact. It is my belief that this is an unrealistic boundary condition,…”

Question: In Evidence #4 Kettering agrees with Dr. Nathan’s findings that “…the collision between bat and ball is over before any information about the handle end of the bat is available to the ball.” If that is the case, then what possible effect could “recoil” of the bat (post-impact) have on ball exit speed?

6. Evidence # 2. What were Brody’s experimental conditions for demonstrating hand-held tight and loose hand grip?

7. Evidence #5. Not fair. In two conditions (pivot and free-free) the ball is moving (pitched) at a stationary bat. In the third condition (swing-hit) the ball is stationary and the bat is moving.

Why not be fair and use three grip conditions with ALL bats stationary ? As in the experiment, fire balls from an air compression cannon towards ALL stationary bats. The three grip conditions:
a) Pivot (clamped pivot free to rotate about an axis point at the handle)
b) Free-free (bat balancing on two small posts)
c) Vise grip (clamped at handle and not permitted to rotate)

Measure ball exit speed of each. My money would be on “c”.




So, what have we learned?

What I do know is that the baseball swing in competition, starts with a loose grip and tightens progressively along the bat path to the ball with max grip power applied at contact or the batter will most likely release his bat either into the dugout or field seats.