Posted by: phil (philipland@aol.com) on Thu Jul 28 18:55:10 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 key here is at contact. All influential forces will be produced prior to contact. The duration of contact is too short to be affected by any similtaneous force.********
>
> 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”?

******Again, these forces are applied prior to contact.******
>
> 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?

****** The point of the study was to show the effect of a fixed vs free bat handle (hence tight or loose grip)on the deflection of the ball from the bat. Again a study on contact conditions. How the bat got to contact is irrelevent to the study. All the study showed was that at contact, the deflection of the ball from the bat was the same for both conditions. The implication is that in the swing, when contact is initiated, the conditions of the hands on the handle of the bat have no determination on the deflection of the ball. Only conditions prior to contact will effect the deflection.****

>
> 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?
>
******At contact, according to the study, it has no effect. Prior to contact you mat see different results.******

> 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?
>
******Recoil of the bat (post impact) is a result of the energy of the ball being transfered to the bat. Energy can neither be creatednor destroyed, so any enerhy expended to move the bat will be lost from the energy transfered back to the ball's deflection. This loss of energy will result in a loss of "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”.

******I would think so too, but it was not supported by the study. May be due to the inherent flex in the bat.******
>
>
>
>
> 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.

******Grip pressure is necessary to hold on to the bat, but may not be a component in generating the forces of the swing. A loose grip allows the athelete freedom from tension which may inhibit fluidity, and allow for a faster swing speed. To assume the subsequent tightening of the grip is necessary to create speed, just because it happens, may not be true. It's pupose may be just to keep the bat fromflying into the dugout or field seats.******