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 can understand the concept of using PP#3 to aim the sweetspot of the clubhead at the base of the inclined plane as one traces a SPL.
However, I have a hard time understanding how the hosel rotates around the sweetspot-to-grip axis - especially with respect to the Robot-Fit golf club testing machine. I would like to read your explanation of how the clubface passively rotates to square by impact in that machine.
...However, I have a hard time understanding how the hosel rotates around the sweetspot-to-grip axis - especially with respect to the Robot-Fit golf club testing machine.
Firstly, if the toe of the club is traveling counter-clockwise (closing Clubface) and the Sweet Spot is the COG of the club, it would follow that the hosel would be traveling counter-clockwise around the same axis.
An analogy that I use is painting a line with a wide paintbrush. Start painting a thin line with the wide brush. As you continue the line, start twisting the brush so that the line becomes wider. Finish the line with the line becoming thinner. The center of the brush (the Sweet Spot) traveled on the same line. The top and bottom of the brush (the toe and heel) rotated around the center, and they travel from on-to-off-to-on the line.
Secondly, as far as the robot goes, it's been so long since I've given a robot a lesson that I can't remember what it does. All kidding aside, I made a phone call to a friend that works for a company that has one. I'll ask him about it as soon as he calls me back.
I can understand what you state about the hosel rotating counterclockwise around the sweetspot axis when the clubface closes - from a conceptual perspective. However, it doesn't "feel" like the hosel is rotating around counterclockwise when I swing through impact - even though I can understand the concept.
I can easily understand the painting brush analogy because the handle is in the center of the brush, and the brush ends are rotating around the sweetspot which is inline with the handle - because in that situation the handle stays centralised while the brush twists. I find it harder to mentally picture the situation if the handle is at one end of the brush and there is a straight line relationship between the grip end of the handle and the one endpoint where the handle attaches to the extreme end of the brush - because the handle will have to twist with that end of the brush.
I can understand what you state about the hosel rotating counterclockwise around the sweetspot axis when the clubface closes - from a conceptual perspective. However, it doesn't "feel" like the hosel is rotating around counterclockwise when I swing through impact - even though I can understand the concept.
I can easily understand the painting brush analogy because the handle is in the center of the brush, and the brush ends are rotating around the sweetspot which is inline with the handle - because in that situation the handle stays centralised while the brush twists. I find it harder to mentally picture the situation if the handle is at one end of the brush and there is a straight line relationship between the grip end of the handle and the one endpoint where the handle attaches to the extreme end of the brush - because the handle will have to twist with that end of the brush.
Jeff.
Then, use a paint roller. Slide the roller, twist it until it rolls, then keep twisting until it slides. It's the same analogy, with an imaginary COG.
Have you seen a lathe in action, and do you get that analogy?
The CG of the club (any club) is not on the sweet spot ... its at a point in space. But the club face sweet spot is connected to the hands via the hossel and shaft not some imaginary line connecting it. If it were not constrained by hands gripping the shaft connected to the hossel, the face would want to open (not close) on the downswing as the inertia caused it to want to line up with hossel on the plane.
The CG of the club (any club) is not on the sweet spot ... its at a point in space. But the club face sweet spot is connected to the hands via the hossel and shaft not some imaginary line connecting it. If it were not constrained by hands gripping the shaft connected to the hossel, the face would want to open (not close) on the downswing as the inertia caused it to want to line up with hossel on the plane.
Since I'm the only alcohol virgin on this website, I may be the only one that remembers this trick. They don't call me the lifetime designated driver for nothing. I remember things that happen in bars.
The COG of the fork and spoon is not inside the fork or spoon. But, we can identify that the Z axis of the COG runs through the edge of the glass, where the toothpick rests. I'm sure that this is the point that you're making. But, it's a nice trick to leave the waitress. It's a real head scratcher.
There can be a rotational center that runs through the COG, and this is what we're seeking. We're looking on the Z axis, as a center of rotation could be found on other axes. The Clubshaft cannot be a center of rotation, since there is nothing on the underside of the hosel to counterbalance the Clubhead.
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).
All kidding aside, I made a phone call to a friend that works for a company that has one. I'll ask him about it as soon as he calls me back.
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