Pivot center

[Yoda]

In another thread, Yoda stated that a golfer needs a i) pivot center and that the pivot center needs to be centralised between the feet.

Of all HKs' ideas I have never understood why there needs to be a pivot center for the swinging arms/clubshaft.

To maintain the Point of Compression (2-C-0) through Impact and for consistent Directional Control (2-D-0), there must be a Centered Arc. Or, a "compensating manipulation". In turn, a Centered Arc requires that both the Pivot and the Arm/Clubshaft Swing be Centered. In other words, the Pivot has its Center, and the Primary Lever Assembly (Left Arm and Club) has its Center. They are not the same.

I can understand a grandfather clock having a pivot center located at the fulcrum of the pendulum because i) the length/radius of the pendulum arm is constant and ii) the low point of the pendular arc is constant.

Yes, this is the mechanical ideal. A centered arc with a constant radius and a low point directly opposite the hinge pin.

However, golfers don't have a consistent ball position and/or a consistent low point - relative to the center of their stance.

A Centered Arc is indifferent to Ball Location and Stance. Hence, Low Point also is indifferent.

Also, the length (radius) of the left arm/clubshaft swinging structure varies continuously during the downswing.

Ideally, the Left Arm remains fully-extended from Start Up to the end of the Follow-Through (6-A-4). The Left Wristcock shortens the Radius (Left Arm and Club) to produce Power through mechanical advantage (2-P; The Glossary / Lever Assemblies and Wristcock).

Also, the fulcrum (left shoulder socket) of the left arm/clubshaft structure moves in space continuously and has a variable distance from the required low point (a set number of inches ahead of the ball).

Indeed, the Left Shoulder ideally is moving in a circle. This requires its own Center (either the Head or the 'Point between the Shoulders'). Otherwise, the Clubhead Arc becomes Uncentered (2-H).

Also, although the low point of the swing is roughly opposite the left shoulder socket area, the left arm/clubshaft length/radius is not necessarily at its greatest value at that time point. The left arm/clubshaft's length/radius is at its greatest value when the left arm is maximally straight and the clubshaft is maximally straight-in-line with the left arm, and that occurs at the end of the followthrough.

Actually, the Left Arm and Clubshaft Radius is at Full Extension within one inch past Impact (2-D-0 / 7th edition). It is this "Right" Timing (6-F-1) that produces Maximum Compression "near -- but prior to -- Full Extension". This Full Extension is independent of the Follow-Through, which by definition (8-11) requires that the Right Arm also be straight (6-A-4).

Maybe that is why HK didn't state that a stationary head is an imperative, but more imprecisely classified it as an essential requirement. Rhythm and balance are also imprecise concepts that are classified as essential requirements.

There is nothing imprecise in Mr. Kelley's terminology, classifications or concepts. The nearest dictionary will provide the necessary "standard of precision" (1-H) for the chosen terminology and classifications. Deliberately using that 'dictionary English' (Preface) -- as opposed to scientific or engineering jargon -- the book itself defines the concepts of Stationary Head, Balance and Rhythm. Its intentional brevity demands that the complete definition of any concept be the sum of all the available references (1-H). Nevertheless, an adequate definition for each is given in The Glossary.

To make any further discussion interesting/informative, I am including a series of photos showing the pivot center of different golfers. I drew red lines through the pivot center (defined as a point midway between the shoulders) at address. I then left the red line constant, and captured two additional images - at the end-backswing and at impact.

From this swing video -

Gary Player



Arnold Palmer



Jack Nicklaus



Mike Souchak



Here is another swing video that is pertinent to this discussion

From this Natalie Gulbis/Paula Creamer swing video -

Natalie Gulbis



Paula Creamer

Regarding the males, perhaps there is a mechanical reason why Mr. Souchak, as good as he was, never won a major championship. Regarding the females, well, let's just say that their actions are "less than ideal" and require a good deal of "compensating manipulation" (see 1-K and my first answer above).

If I were considering essential requirements (and not imperatives) for a golf swing, I would consider removing "stationary head" and inserting "set distance of the left shoulder socket from the ball at impact".

Mr. Kelley understood that the Left Shoulder is higher at Impact (7-8 ) than in the normal Adjusted Address position (8-3). Further, he gave us a comprehensive three-step routine for accomplishing that specific objective with unprecedented precision (2-J-1). Fortunately, he understood that these adjustments were a means to an end -- creating a uniform Arc -- and not the end in themselves.

[Mike O]

Actually, the Left Arm and Clubshaft Radius is at Full Extension within one inch past Impact (2-D-0 / 7th edition).

Here is the exact quote:
"The Lever Assembly is seldom more then an inch from Full Extension at Impact".

[Yoda]

Here is the exact quote:
"The Lever Assembly is seldom more then an inch from Full Extension at Impact".

Agreed, Mike: There is a difference between my conclusion (point of Full Extension past Impact) and the "exact [Kelley] quote" (degree of Extension at Impact). For practical purposes, I believe that my conclusion is valid.

Remember, the Left Wrist doesn't go from Cocked to Level -- then hang around a while -- and later proceed to its Uncocked condition. No sir, the Left Wrist is rapidly Uncocking -- perpendicular Wrist MOTION (4-0 / 4-B) -- and it is Releasing in one unbroken thrust. Even with the Swinger's Sequenced Release (4-D-0), there is an overlapping of the #3 Accumulator Wrist Roll and completion of the #2 Accumulator Wrist Uncocking.

In any event, the Left Wrist ideally is Level at Impact and then immediately proceeds down approximately one inch to fully-Uncocked through the Impact interval. No way does this complete Uncocking take until the end of the Follow-Through (which was Jeff's point).

Mike . . .

I don't want to get too far from the subject of this thread, but since you've raised the question . . .

If at Impact, the Primary Lever has only one inch to go until it reaches Full Extension, and if the Left Wrist is Releasing freely, then what is your best guess as to when Full Extension occurs, i.e., how far past Impact?

[Mike O]

Mike . . .

I don't want to get too far from the subject of this thread, but since you've raised the question . . .

If at Impact, the Primary Lever has only one inch to go until it reaches Full Extension, and if the Left Wrist is Releasing freely, then what is your best guess as to when Full Extension occurs, i.e., how far past Impact?

Whenever the #3 accumulator becomes the smallest.

[Yoda]

Whenever the #3 accumulator becomes the smallest.

Agreed.

In Homer-speak, that would be zero.

[Mike O]

Agreed.

In Homer-speak, that would be zero.

If you started with a small enough number 3 accumulator where you could make it to zero, via the uncocking motion. Otherwise, based on the grip taken maximum extension would be maximum uncocking regardless of whether you made it to zero #3 or not.

[Yoda]

If you started with a small enough number 3 accumulator where you could make it to zero, via the uncocking motion.

But, Mike O . . .

What if you had the club down well in the fingers, you know, at or below the proximal phalanges http://en.wikipedia.org/wiki/Proximal_phalanges?

Would this be a maximum #3? If so, what does this imply? And what if you were older and couldn't zero it because of an arthritic condition? Would this eliminate the #2 accumulator? How about #3? I see no reason for that because clearly Moe Norman never did either. For example, consider http://perfectgolfswingreview.net/swingplane.htm. It doesn't come close to the breadth of my argument, but you get the idea. Plus, if you'll draw the lines -- I see no need to go to that extreme here since it is obvious and everybody can see it -- you'll see that his head moved at least .0001 of an inch (in front of the ball . . . but that is in a different place than Ben Hogan's or Jack Nicklaus's ball). BTW, is that right? You know, should it be Nicklaus's or should it be just Nicklaus'?

Finally, would any of this affect my ability to pivot Saturday night at Hernando's Hideaway?

Please don't delay your post . . . "I gotsta know."

P.S. Jeff, please don't take offense, you know "I luv ya, man!" And sincerely appreciate all you are doing here. It's just that sometimes . . . it can get to be a bit much. But that's you, and I'm growing fond of your deep-digging. Keep it coming, my friend; just know that there are time constraints on my ability to read your insightful posts, let alone comprehend and respond.

[Jeff]

Here is a simple thought experiment as to whether Tiger's driver clubhead arc should be elliptical or perfectly circular in shape, and whether two consecutive driver swings would have clubhead arcs of exactly the same elliptical shape.

To make the experiment simple, consider that the pivot center (base of the neck at C7) remains fixed in space during the downswing between swing A and swing B. Also accept that the clubhead is in exactly the same identical 3-D position at the start of the downswing in those two swings.

Now consider what factors will affect the position of the clubhead in space at different time points during the downswing. Imagine a very accurate timer that can measure the downswing action in millionths of a second, and let's determine where the clubhead will likely be located after xx/100th of a second into the downswing.

There are six interacting variables that will influence the clubhead position after xx/100th of a second.

1) The speed of rotation of the left shoulder socket around the "fixed" pivot center.

2) The exact angle of rotation of the left shoulder socket around the "fixed" pivot center. For example, in swing A the left shoulder may rotate around the pivot center at a 90 degree angle while in swing B it could be at an 85 degree angle.

3) The speed/timing of left arm rotational movement around its left shoulder socket fulcrum point which depends on the PA#4 release pattern.

4) The angle of the left arm's rotational circle relative to the left shoulder socket - relative to the inclined plane.

5) The precise timing of release of the clubshaft (uncocking of the left wrist) and therefore the precise timing of the lengthening of the left arm-clubshaft radius.

6) The angle of the clubshaft release relative to the back of the left hand. Hopefully, the left wrist will uncock perfectly in plane with the left arm so that the clubshaft will release in the same planar arc of the flat left hand, but there could be a variation of a few degrees from swing-to-swing.

One doesn't have to be a rocket scientist to realize i) that the 3-D clubhead position at xx/100th of a second will not likely be in the same precise 3-D location in swing A compared to swing B; ii) that the total clubhead arc shape will more likely be elliptical in shape rather than perfectly circular in shape; iii) that there is no fixed center of an elliptical arc; iv) that there is no necessary causal reason why the pivot center (base of the neck) should be at the "center" of that elliptical-shaped clubhead arc.

It also doesn't require a rocket scientist to realize that the i) low point of that elliptical clubhead arc may be just inside the left foot, or somewhere else - dependent on the "fixed" position of the pivot center; and that if the low point is just inside the left foot that it doesn't necessarily imply from a causal perspective that the pivot center must be in the center of the stance.

Jeff.

[O.B.Left]

Yoda

This is one heck of a post.

Jeff your persistence does bring out the best from the best. But what is the nature of this mission that you are on?

O.B.

[Mike O]

Yoda

This is one heck of a post.

Jeff your persistence does bring out the best from the best. But what is the nature of this mission that you are on?

O.B.

O.B.,
Since Jeff will give you some story about searching out the truth et.c etc. Let me answer this for you - his mission is to drive people insane- Bucket and I have him on a retainer fee for this exact purpose.