Jeff.
Thanks for the links. Not universal joint though. It looks like synchronized shaft rotation with uncocking action through gears. Wish I could have similar arrangement on my wrists.
I talked to Paul Wilson of Swing Machine Golf who has seen up close (and met the designer of) Iron Byron and he says it too has gears to close the club face 90deg in the downswing. They did because its part of the deceleration mechanism (shafts were breaking post impact without gears controlling the decel) and because Bryon Nelson did it. He said they all do (swing machines) so I guess *(and it looks like in the video it must)* pingman does as well.
I see no reason why the club face would open/close on its own as a result of interial forces.
I see no reason why the club face would open/close on its own as a result of interial forces.
The club is on a tilted plane, and thus has the 'out' of down, out and forward built into the physics of the machine and the design of the club.
IF
the machine is perfectly on plane - the line of pull.
The design of the club will pull the toe 'out' for proper impact. Try swinging a hockey stick, or any number of aids that exagerate the 'toe' of a club, they force that shaft to turn around the COG - sweetspot.
A perfectly on plane swinger, or machine, doesn't need to cause the out. Realistically, nobody is that perfect, so the release is often 'caused' by the golfer (release swivel).
the design of the club, and the physics of the COG plane, require that the shaft rotate around the sweetspot (per Ted's baseball bat example).
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Take a dowel rod... that represents the shaft. Take a push-pin or nail and put it in the end. Find a hex nut and tie it on a string then tie the other end to the nail or push pin on the dowel. The nut is the COG of your "club head. Take it out side and swing it every which way...up, down inclined... it doesn't matter. The Nut will never move off the plane of the swing (as defined by the dowel). The nut dutifully follows the shaft (unless/until it "releases" in the plane of the swing not perpendicular to it). There is no physical force/torque which causes the club face to open and close besides that which is supplied by the golfer's hand. Golfing machines use gears to achieve what the golfer's hands do naturally.
The club is on a tilted plane, and thus has the 'out' of down, out and forward built into the physics of the machine and the design of the club.
IF
the machine is perfectly on plane - the line of pull.
The design of the club will pull the toe 'out' for proper impact. Try swinging a hockey stick, or any number of aids that exagerate the 'toe' of a club, they force that shaft to turn around the COG - sweetspot.
A perfectly on plane swinger, or machine, doesn't need to cause the out. Realistically, nobody is that perfect, so the release is often 'caused' by the golfer (release swivel).
the design of the club, and the physics of the COG plane, require that the shaft rotate around the sweetspot (per Ted's baseball bat example).
Could you please expand on your belief that the clubshaft rotates about the COG of the clubhead?
When I swing a golf club or a hockey stick across the front of my torso, I can see the clubface closing so that the toe of the club eventually passes the heel. I can also see that the clubshaft hosel has a rounded arc motion. However, I cannot see the clubshaft rotating around the COG of the clubhead. Where should I be looking to see that phenomenon happening?
Could you please expand on your belief that the clubshaft rotates about the COG of the clubhead?
When I swing a golf club or a hockey stick across the front of my torso, I can see the clubface closing so that the toe of the club eventually passes the heel. I can also see that the clubshaft hosel has a rounded arc motion. However, I cannot see the clubshaft rotating around the COG of the clubhead. Where should I be looking to see that phenomenon happening?
Jeff.
Suspend an iron vertically waist high holding the grip end gently with two fingers ( thumb and index). Spin the grip around with your wrist and fingers.
Watch the shaft rotate around the sweetspot.
I cannot clearly understand your experiment. Do you have a small flexible piece of string of finite length (eg. 3") between the nut and the peripheral end of the dowels stick? If yes - then I can imagine the string following the plane of clubshaft movement with the hex nut dragging behind in the same plane. However, what happens if you attach the hex nut to the peripheral end of the dowel stick with a piece of rigid metal about 3" in length and then move the dowel stick in a rounded arc - as if you were swinging it like a golf club across the front of the body?
I have no problem seeing the clubshaft hosel rotate around the sweetspot in your example - where the grip end (fulcrum point) remains stationary and the clubshaft hangs vertically, and the sweetspot remains in the same spot in space while the club is being twirled.
However, the clubshaft's grip end is moving continuously in space along a rounded arc of motion during the golf swing, and while it is moving the clubshaft's grip end is also rotating in direct proportion to the degree of rotation of the flat left wrist/hand. While this is happening, I cannot see the clubshaft hosel rotating around the sweetspot. Can you?
I have no problem seeing the clubshaft hosel rotate around the sweetspot in your example - where the grip end (fulcrum point) remains stationary and the clubshaft hangs vertically, and the sweetspot remains in the same spot in space while the club is being twirled.
However, the clubshaft's grip end is moving continuously in space along a rounded arc of motion during the golf swing, and while it is moving the clubshaft's grip end is also rotating in direct proportion to the degree of rotation of the flat left wrist/hand. While this is happening, I cannot see the clubshaft hosel rotating around the sweetspot. Can you?
Jeff.
I cannot see the fingers of the pianist playing Mozart that misses a key, but I can hear it. Must everything been seen to know?
if you took a strip of sheet metal say 1 inch wide by 6 inch long and wrapped it around the end of the dowel and attached it to a weight, it's stiffness would prevent it from "releasing" in the plane of the golfswing while still allowing to rotate out of the plane of the swing (provided it doesn't bind up) if indeed it were subjected to a force that caused it to want to rotate out of the plane of the swing. I submit there is no force that causes it to want to rotate out of the plane of the swing.
Generally speaking..
Any object (a shaft for instance) will naturally want to rotate about an axis defined by its angular momentum vector. But all real objects are constrained to rotate about random axis which due to manufacturing tolerances is never aligned with the angular momentum. This unavoidable misalignment between angular momentum vector and axis of rotation causes imbalance forces. (Lathe imbalance for instance). But this has nothing to do with the face of a golf club opening and closing.
What we have with a golf club is the CG of each element of its contruction (head and shaft) wanting to find their way ONTO the plane of rotation (not off of) the plane of rotation. But... the club head being attached to the hossel is forced to rotate off plane (against its natural inclination) as the golfer's hands cause the shaft to rotate about its longitudinal axis.
Originally Posted by Jeff
nm golfer
I cannot clearly understand your experiment. Do you have a small flexible piece of string of finite length (eg. 3") between the nut and the peripheral end of the dowels stick? If yes - then I can imagine the string following the plane of clubshaft movement with the hex nut dragging behind in the same plane. However, what happens if you attach the hex nut to the peripheral end of the dowel stick with a piece of rigid metal about 3" in length and then move the dowel stick in a rounded arc - as if you were swinging it like a golf club across the front of the body?
You wrote-: "f you took a strip of sheet metal say 1 inch wide by 6 inch long and wrapped it around the end of the dowel and attached it to a weight, it's stiffness would prevent it from "releasing" in the plane of the golfswing while still allowing to rotate out of the plane of the swing (provided it doesn't bind up) if indeed it were subjected to a force that caused it to want to rotate out of the plane of the swing. I submit there is no force that causes it to want to rotate out of the plane of the swing."
You state that there is no force that would cause the clubhead to rotate out of the plane of the swing. That would be true if the hands propelling the dowel stick didn't rotate the dowel stick about its own axis while the dowel stick is being moved in a rounded arc. However, the left hand holding the dowelstick may swivel counterclockwise while the left hand is moving the dowel stick in a rounded arc. Wouldn't that cause the clubhead to change its position relative to the clubshaft, and wouldn't that change in position of the COG of the clubhead cause it to rotate even more - because the COG of the clubhead has shifted in space relative to the overall orbit of the dowel stick's hosel?
I am thinking of a similar argument to your argument about the release phenomenon - where the club acquires angular velocity because the hand directional pull is not in-line with the COG of the club.
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