I want to add a backswing point not too clear to the discussion:
On the dowswing, centrifugal force mantains the longitudinal mass gravity centre of the lever assembly (left arm, club), which is the sweetspot, on the same 2 dimensional (flat) circular trajectory. Especially in release, we can see the sweet spot staying on The Plane, or just staying moving in the same flat circular motion, while the lighter hands come closer to the body and near to the ground when rolling the wrists (with uncocked wrists, but plenty nº3 accumulator).
In the backswing(from address to end/top) rotating the shaft around the sweetspot and not viceversa is very difficult, and having the sweetpot as a "fixed or rotation fixed point/centre" reference point is very difficult. Here little centrifugal force can be generated. So when a turn in the left wrist is made, the club (shaft and club head) moves around the hands.
So when Homer Kelley was talking about "rotating the shaft around the sweetspot and not viceversa" maybe he is only adding this to the dowswing.
Because in the backswing it is better I think to have as reference point the hands moving with the same thrust' direction on the same plane and controlling the hands (rotating the clubhead/shaft around the hands). Because when you attempt to rotate your hands around the clubhead(club's sweetspot), rotate the hands (by turning action of the wrists) around a "sweetspot moving in a 2 dimensional angular motion(on the plane)", the club's sweetspot will be throwed out of plane (becomes 3 dimensional sweetspot's path) by not on plane forces that don't move in the same direction along the plane or flat circular trajectory. Not on plane forces such as cocking(when the left wrist cocking action is not on plane, i.e. when the left back of the hand is not facing/resting on the sweetspot plane), also turning/rolling with non zero nº3 accumulator is not an on plane force with the plane the sweetspot had previous to starting the turn/roll.
An experiment to illustrate this, hold a very light dowel and get with zero pivot on a position in the downswing when the right forearm is level to the ground. Point the dowel to your intended line of flight(to the ball), and then swing to impact very very very slowly. In the way down roll fast, snap rolling your wrist (but keep the hand's slow but even thrust) so at impact the imaginary clubface will be vertical to the intended line of flight. There you can see that the dowel rotated around the hands, the hands kept the same direction of motion (or in the same path), while the extreme of the dowel that would be the clubhead moved outward far beyond the line of flight, and the dowel missed the ball because the dowel moved away, and the hands mantained its position.
Incrementing the experiment's downswing velocity increases the centriugal force, and the effect "sweetspot/dowel impact zone becoming out of 2 dimensional plane, flat surface" is minimized. The backswing velocity is smaller in comparison to the velocity we can see at release.
Can you TGM's confirm if at the backswing you follow the sentence "rotate around the sweetspot", or do you turn the left wrist and move/rotate the clubhead around the hands, mantaining the hands in an ideal flat surface/plane and then when that is done, a little later you put the sweetspot on that same plane the hands are moving in.
Glue or tape a string to the sweetspot of the clubface and attach the other end to the grip. The sweetspot plane runs from pp3 at the grip to the center of the clubface. With this string attached, watch the shaft rotate around it on both the Take-Away and the Down Stroke. A thing of beauty.
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