the illusive and invisible sweetspot plane

[YodasLuke]

This is in the lab for a reason. If you find it "harder to read than TGM", don't read it.

For anyone that still doesn't see the center of mass or "center of gravity" of an object (Cg(m)), here's an example:

Imagine a baseball bat being carved on a lathe. The finished bat is symmetrical in cross section. It would be very easy to cut the bat in half at any circumference and find the longitudinal centerline of the bat or the center for that circle. When a bat is finished, you could crank the lathe up to 1000 mph, and the bat would not waiver. But, since the bat is heavier on one end, you could balance it on a balance beam to help find the bat's Cg(m). One laser fires longitudinally through the center line of the bat and one fires through the balance point established by the balance beam. The intersection of those beams would be the Cg(m).

A golf club on the other hand is asymmetrical in cross section in addition to being heavier on one end. The longitudinal centerline for the bat is the same as this example in a golf club: "The spot on the Clubface through which a plumb-bob line would pass if suspended from the Grip area." As a result, the Cg(m) doesn't reside in the mass of the club. If this invisible, longitudinal centerline of the golf club was arranged on the lathe as was the center of the bat, you could crank up the speed of the lathe again. But, if the longitudinal centerline was the shaft, I'd suggest you go in another room when the lathe gets cranked up. Something's going to break loose, because the clubhead will wobble.

Additionally, the Cg(m) being mid body for a human has nothing to do with a pivot center. It's just a regurgitation of an intelligent sounding phrase: "center of gravity". Once the concept of Cg(m) is understood, its application to moment of inertia is important. Moment of inertia should always be discussed relative to an axis of rotation. This axis might run through the Cg(m) or it might not. The pivot axis does not go through the human Cg(m), making MOI and axis important in this case as well. In the golf club case, the MOI is usually discussed about the club shaft axis, since we have our hands attached to it. The clubshaft MUST leave the plane.

Yoda likes to use the analogy of someone throwing a hatchet at a wall. It's another example of something that doesn't rotate around it's shaft.

If you don't see the analogies above, shank you anyway for your time,
Ted Fort

P.S. Thank you, Thinkingplus, for the validation and suggestions. For anyone that doesn't know, she's the queen of physics.

[ThinkingPlus]

Ted,

My pleasure, however, so that everyone knows, I have a degree or two in physics, but do not consider myself a physicist. That title is reserved for those that Pile'it Higher & Deeper. I have not done much physics in many years allowing for the distinct possibility for mistakes. Caveat Emptor!

[alex_chung]

Ted,

My pleasure, however, so that everyone knows, I have a degree or two in physics, but do not consider myself a physicist. That title is reserved for those that Pile'it Higher & Deeper. I have not done much physics in many years allowing for the distinct possibility for mistakes. Caveat Emptor!

Piled Higher and Deeper..great online comic strip
As for being a Physicists, I did 4 years at University and that was enough for my poor head......
Interesting post you have there Ted.
Alex

[Thom]

When we are setting up with the right forearm onplane, it should actually look a tiny bit (a couple of degrees) under the shaft plane from the down the line perspective?

Or is that being a little too scrupulous ( eh found that word in the dictionary - remember, english is only my second language)

[EdZ]

Yoda likes to use the analogy of someone throwing a hatchet at a wall. It's another example of something that doesn't rotate around it's shaft.

Yes, but it does rotate (balance) around its center of Mass.

[Martee]

YodasLuke wrote in my Ah-Ha 0002-2006 thread...
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I just started a new thread in The Lab, "the illusive and invisible sweetspot plane". It's in there because it might be a little over the top for those that live by the K.I.S.S. mantra.

Let me first apologize if my High Level of Frustration comes out, it is really intended to anyone, it is I am just frustrated. I ask questions, get quoted reference from the book which I have already referenced in my question. I can't get an answer other than what comes across is 'just accept it, believe it, etc.'.

Now I am not in anyway trying to disprove TGM, in fact what I am trying to do is get some clarification so it more understandable. I really don't understand, am I just as dumb as a box of rocks?

1. I have never said that the Sweet Spot Plane and Angle doesn't exist. In fact in part in my journey it is clear that the concept of the Sweet Spot Plane and Angle is what IMO bridges the gap between mechanics and feel.

2. My questions still go unanswered. Is there anyone who can just answer each question directly and not write a dissertation of generalities?

I would hope this doesn't go unresponded too but I believe in my other thread if you look at the questions, view the references, maybe you can show the error of my ways.

My quest started to just better understand analyzing videos/photos and understanding general golf terms applied to TGM to communicate clearly. Also I challenged the use of Plane Board, both in TGM and as a valid training aid and again, even in the initial post here validates my position that it is not validate if I am to accept the that there is no difference between the 'Feel' and 'Mechanics' in the swing.

If anyone wants I can repeat the questions and references in this thread.

[YodasLuke]

Let me first apologize if my High Level of Frustration comes out, it is really intended to anyone, it is I am just frustrated. I ask questions, get quoted reference from the book which I have already referenced in my question. I can't get an answer other than what comes across is 'just accept it, believe it, etc.'.

Now I am not in anyway trying to disprove TGM, in fact what I am trying to do is get some clarification so it more understandable. I really don't understand, am I just as dumb as a box of rocks?

1. I have never said that the Sweet Spot Plane and Angle doesn't exist. In fact in part in my journey it is clear that the concept of the Sweet Spot Plane and Angle is what IMO bridges the gap between mechanics and feel.

2. My questions still go unanswered. Is there anyone who can just answer each question directly and not write a dissertation of generalities?

I would hope this doesn't go unresponded too but I believe in my other thread if you look at the questions, view the references, maybe you can show the error of my ways.

My quest started to just better understand analyzing videos/photos and understanding general golf terms applied to TGM to communicate clearly. Also I challenged the use of Plane Board, both in TGM and as a valid training aid and again, even in the initial post here validates my position that it is not validate if I am to accept the that there is no difference between the 'Feel' and 'Mechanics' in the swing.

If anyone wants I can repeat the questions and references in this thread.

I understand completely, Martee. And, I also understand that it's very easy to get frustrated, when we find words in TGM that say "unless otherwise noted." My post above was not directed at anyone either, but it's one of the many ways that I try to explain away the sweetspot rotating around the shaft. You understand that there are millions that don't nor will they ever see that simple concept.

Do you want me to go back to the thread and bring the questions in here? Or, would you like to put the discrepancies in a "x" versus "y" scenario? Also, I'm certainly not an omnipotent and omniscient immortal that lives here on Earth. I am on the same quest as you, and I learn something new everyday. But, I'd be glad to share whatever knowledge I'm able to give to you or to anyone else.

By the way, I'm in agreement with you about the use of Plane boards or the use of the big pvc circles, etc.

[Martee]

Sorry Ted, it is just that, well I am Frustrated cause some comments made are without the correct qualifiers IMO and this is base on going through TGM, all the forums, etc. If I have one word doc on Planes,Lines and Angles, I have two dozen. I keep starting all over. Plane Boards, lines on photos, etc. all just drive me up the wall when I apply my obviously limited understanding of TGM.

I am not a good writer and more often than not don't express myself well, I keep at it but that damn wall is starting to hurt this head of mine....

I will open another thread up, try and keep it to a single point, though I am really trying to figure out this thing called a Target Line wrt to Plane Line and Line of Flight.

Thanks for you consideration...Off to a new thread...

[Martee]

YodasLuke wrote ..
Moment of inertia should always be discussed relative to an axis of rotation. This axis might run through the Cg(m) or it might not. The pivot axis does not go through the human Cg(m), making MOI and axis important in this case as well. In the golf club case, the MOI is usually discussed about the club shaft axis, since we have our hands attached to it. The clubshaft MUST leave the plane

An accurate description but the conclusion is not an absolute. This makes several assumptions IMO:
1. That the shaft is being rotate external to the source of force.
2. That the center line must oriented to point or have a relationship on a tangential straight line from its initial reference at all times.

I need to think some more on this. I know where you are going with this but I am not sure you can establish this as an absolute. The hatchet, it goes end over end more like in an elliptical orbit as it goes forward, not quite what I would equate to the golf club.

For anyone who doesn't believe that the this invisible line doesn't exist, probably doesn't believe that gravity exist.JMO.