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Putter Weighting and Topspin

March 7 2004 at 5:07 PM
JPVegas  (Login JPVegas)
from IP address 81.129.39.29

 
Geoff:

Has any research been done on the optimal placement of the center of gravity (COG) to enable the golfer to most easily impart topspin to the ball? Ping and other putter manufacturers have low COG putters and clain that because of the gear effect, this most effectively enables topspin. Recently I have read other manufacturers, (Yes/Big Oak), claims that putting the COG close to the top edge of the putter enables topspin. Any thoughts or ideas on this?

 
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Geoff Mangum
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172.131.126.228

Path of COG - not Height - is Probably Key

March 9 2004, 6:02 PM 

Boy, did you ever put your finger on the heart of the matter! There are two big issues in putter design right now -- location of the COG in 3 dimensions and how to hosel. The COG issue is being handled in diametrically opposite ways by three camps among putter manufacturers (low, high, level), each backed up by "true roll" studies, and neither really communicating or debating the issue directly. I'm not sure how this will all finally sort itself out, but clearly there must be some basic uncertainties in the definitions or understandings about the underlying physics. perhaps it is only a matter of the "relevant" physics, and the real choices are occuring in how the golfer actually uses one type versus another.

The three dimension of COG location in the putter head can be related to the X, Y, and Z axes of a standard Cartesian coordinate system with its origin (intersection of axes) located in the ball's COG. The X axis is the same as the direction of the putt or left-right from the golfer's point of view, the Z axis is up-down, and the Y axis if front-back or near-far. The choices are 1) centered heel-toe in the Y axis, 2) high or low in the Z axis in relation to the ball's COG at impact, and 3) close to the putter face or farther back in the putter head in the X axis. The one dimension addressed by your question is the Z axis (2).

The Golfer stands where the upright blue arrow is located. The ball is located in the center of the axes.



The Center of Gravity (COG) of the ball is located in the center of the sphere, unless the ball is out of balance or out of round.



Let's leave aside for the moment the fundamental question of whether topspin is desireable, and if so, why and how desireable is it -- or the correlated question of whether backspin is undesireable, and if so, why and how undesireable is it -- questions that seems to be somewhat unexamined in detail, and certainly deserving of greater scrutiny and scientific investigation.

Camp 1 - LOW COG FOR "GEAR EFFECT"

Those who make a low COG putter include C-Groove / Yes!, Scotty Cameron, Ping Craz-E, Q-Roll, the Resso, and many others. And there are different approaches to accomplishing the same thing.

Typically, the putter design simply has a concentration of mass low on the back flange, as does the C-Groove Amy model:



Ontic, for example, in effect has a "heel-toe" scheme in the vertical dimension, with low sole plates on the heel and toe, and a raised sole in the center. This effectively lowers the putter COG.



The person who seems to have the best studies supporting a low COG putter design is Norman Lindsay at his website Lindsay Putters. He combines a number of design features into his "All Topspin (All-TS)" putters, including a low COG. His site illustrates the high-speed camera studies he's done, and explains the "gear effect" producing topspin by a low COG combined with certain lofting features and certain impact dynamics resulting from the way the golfer presents the putter face to the back of the ball.



Lindsay writes:

The facts are:

* All conventional putters impart backspin.
* Some can also generate a little topspin.
* The amount and direction of spin depends on where the ball impacts the striking face.
* With any golf club (from putter through to driver), the higher the point of impact on the clubface, the less the backspin.
* With a putter – if the design is right – the spin becomes topspin for impacts near the top of the face.
* A badly designed putter can give so much backspin that the ball loses 35% or more of its initial energy through skidding before it gets rolling. (High topspin putters can reduce this to 20% or less.)

Lindsay putters impart high topspin over the entire striking face, providing modern-age performance that would enthral bygone masters such as Bobby Locke. This unique achievement is the result of expertly combining the only two mechanisms that genuinely put spin on a golf ball, namely;

* Gear-effect, which relies on the putter-head weight distribution, but is also critically dependent on the way the shaft attaches to the head.
* Oblique impact - the workhorse of golf shots. This shapes flight trajectory and puts backspin on the ball. Backspin is essential for distance in long shots and control in approach shots. In putters, it can be used ‘in reverse’ to give topspin.


So Lindsay says reducing backspin / increasing topspin comes ONLY from the gear effect and certain dynamic loft thru impact, which he terms "oblique impact."

Lindsay elaborates about these two sources:

WHAT GIVES TOPSPIN?

* Vertical gear effect
It’s well known that hitting the ball off the heel or toe of a driver puts sidespin on the ball, even if the clubface is square at impact. The same happens with a putter. What’s less well known is that vertical spin changes with impacts above or below the sweet spot. Hits above the sweet spot (on a putter) give topspin. Hits below the sweet spot give backspin.

* Low centre of gravity
The sweet spot must be low to ensure vertical gear effect works to give topspin. In most putters the CG is not low enough to place the sweet spot below the centre of the striking face. Lindsay putter-heads have exceptionally low CG with the sweet spot well below centre. For hits at or near the centre, topspin compensates for linear ball velocity changes, giving superb putt length consistency. [This is the Z-axis.]

* Deep centre of gravity
Gear effect is proportional to the depth of the CG behind the putter face. For good topspin you need the putter-head CG positioned from half to two inches behind the face. [This is the X-axis.]

* Low minimum inertia
Low minimum inertia (front-back weighting) assists vertical gear effect, giving higher topspin. At the same time it’s important to have high heel-toe weighting (i.e. high maximum inertia).

* Variable face loft
Gradual loft reduction (face roll) can be used on the bottom of the putter-face to introduce a small amount of negative loft. This generates topspin by oblique impact, even though the ball is hit on the upswing on this part of the putter-face. This arrangement is especially beneficial for length control on long putts.

* Centred shaft axis
Lindsay’s recent pioneering research into putter impact has revealed a major problem - the position of the shaft axis is critical for vertical gear effect. Aligning the shaft axis with the putter-head CG ensures the best performance for topspin and feel. [This refers to centering on the Y-axis heel-toe.]


Apparently, the "gear effect" adds topspin when the point of impact on the putter face is centered in the Y-axis, the putter COG is lower than the point of impact on the back of the ball in the Z-axis. Lindsay considers locating the COG back along the X-axis, plus hoseling the shaft in the center of the Y-axis, plus minimum front-back weighting, plus the radiusing of the face in the lower half of the face to help out when the point of impact on the ball is too low, plus minimal lofting or even negative lofting in the radiusing low on the face, all as promoting topspin in some supplemental or complementary way. But I gather that the real fundamental is the "gear effect." So the "gear effect" is pretty much a low COG in the putter face, impact high on the face, impact on the equator of the ball, and the putter COG lower than the ball COG at impact.

Camp 2 - HIGH COG AND THE CUE-BALL LEVEL BLOW THRU THE TOP QUADRANT

The second approach is to locate the putter COG high on the face (Z-axis) and replicate what happens when a cue stick imparts top spin to a cue ball in billiards. Daish in his book The Physics of Ball Games describes how a level blow of the cue stick thru the top quadrant of the cue ball at a height 5/7th the way up from the bottom of the ball perfectly matches the forward translational force with the rotational top-over rolling of the ball to eliminate skid entirely. In effect, the pointed stick delivers the stick's COG level thru the top quadrant of the ball higher than the ball's COG. Putters that take this design approach include the Tear Drop, the Breeds Confidence, the Big Oak, the Aserta, and others.



But since the putter face COG is above the ball COG with the face moving level or rising thru impact, doesn't this present a "gear effect" scenario in reverse -- one in which the putter face tilts bottom-back-up so that the face ought to wheel down counterclockwise on the back of the ball, imparting back spin (which would be slice spin for the driver)? In this case, it is probable that the vertical hosel has less tendency to oppose the counterclockwise action of the putter face than it does in the case of a clockwise gear effect. So a high-COG putter ought to impart back spin the same as or perhaps more than a low-COG putter ought to impart top spin by virtue of the "gear effect."

The Aserta company has comparisons of skid distances of the Aserta putter versus other putters, based on robotic putting tests performed with the Swing Dynamics Putting Track Monitor. The description of the testing procedure does not make clear the trajectory of the putter COG in relation to the ball's COG. Even so, the data shows a forward spin on the Aserta putts in excess of 100 revolutions per minute (about 1.7 revolutions per second) versus back spins of the order of 35 to 60 revolutions per minute (about 0.5 to 1.0 revolutions per second) back spin. See Aserta Inverted Mass Technology. This data just deepens the mystery.

Camp 3 -- COG-to-COG Level

The T-Roll Putter from perry Golf has a design in which the putter COG is the same height as the ball COG. The ball COG is one-half the diameter of the ball up, or in the center, 0.84 inches above the bottom of the ball. The idea is to promote "solid" impact and solid "feel."



The relative positions of the COGs is described for the T-Roll versus the conventional design:





The T-Roll company has a fairly clear explanation of the theory;

Most golf putter heads are heel and toe weighted to create a larger 'horizontal' sweet spot. They have very little mass at the center and top of the putter head. Most of the weight is at the bottom or sole of the putter head. The 'Sweet Spot' is positioned below the center of mass of the golf ball. Since the 'sweet spot' is located below the center of mass of the golf ball, the putter upon contact with the golf ball does not have a very solid feel. Also, most putters are designed with the shaft connected at the heel, inside the center of mass. Upon contact with the golf ball, the putter head tends to twist and rotate on a horizontal plane.

The T-Roll® golf putter is designed with most of the weight located away from the center of mass, creating a very high moment of inertia. (The T-Roll® Defiant with Brass plug inserts is 4699 gm*cm^2.  The T-Roll® Defiant with Tungsten plug inserts is 6431 gm*cm^2.)  Also, the 'T' shaped mass on the The T-Roll® golf putter shifts the center of mass towards the top of the putter head, aligning itself horizontally with the center of mass of the golf ball. By aligning the 'Sweet Spot' on the putter head perfectly with the center of mass of the golf ball, this creates the most solid feeling putter possible. The shaft is connected to the 'T' shaped mass near the sightline. The putter head does not twist or rotate upon contact with the golf ball. Due to its high moment of inertia, even off-center hits cause minimal twisting or rotation of the putter head.


This analysis leaves out, however, the PATH of the putter COG relative to the ball COG thru the ball / impact zone. I suspect that in practical use the T-Roll's "level with the ball" COG merely functions to ensure that the path of the T-Roll COG stays above the ball''s COG. Afterall, a truly level COG-to-COG blow thru the ball would result in all skid. I would not think the 3-degree lofting of this putter would help reduce skid, as this makes the ball rise on the putter face so the ball COG is higher than the putter COG. However, if this effect is overcome by the putter rising into the back of the ball on a high trajectory, then the face loft effect is neutralized and overcome.

SORTING THIS OUT AS BEST WE CAN

Let's get a drink of water, and then go back to the basic idea of "gear effect."

GEAR EFFECT & PUTTING

In a driver, the "gear effect" imparts some hook spin on a ball hit near the toe, or slice spin on a ball hit near the heel, with the driver COG centered on the Y-axis heel-toe. Placing the COG back in the driver from the face on the X-axis increases the gear effect. According to Cochran and Stobbs, Search for the Perfect swing, pages 117-119 (and especially Fig. 19-10), the toe gear effect has the club COG moving along a line not thru the ball COG but inside it, so the toe hits the back of the ball and not the center of the club and COG hitting the back of the ball. This sort of impact knocks the face of the club open. The ball and club face act as if in contact like two enmeshed gears. The backward opening of the face (clockwise for a right-hander looking down at the top of the club) spins the ball the opposite way, counterclockwise, which is a hook spin. The opposite tendencies at work are an open face imparting some slice spin and starting angle off to the right, versus the gear effect imparting hook spin. The trick is for the gear effect to be designed in just right to overcome the slice spin so the ball starts right but then curves hookish back to the center of the fairway.

The "bulge" of a driver face is a curvature of the face along the Y-axis horizontally. This toe curve increases the slice spin and the start angle to the right. Most golfers probably think the bulge increases the gear effect, but this is not correct. A FLAT driver face basically has too much gear effect designed in, and the bulging removes some of the gear effect to get the balance adjusted between slice and hook spin. Too much bulge and the balls just slice.

Applying all this to a VERTICAL gear effect and considering the difference between driver and putter impacts with a ball and the difference in the heel hoseling of drivers that is essentially like a stick entering the driver head horizontally at the heel versus a putter hosel that is a stick entering the head vertically and the difference between balls spinning in the air and balls rolling on the ground, it is fairly evident that the driver "gear effect" horizontally and the putter "gear effect" vertically may not have all that much in common in their physics.

SKID, ROLL, and SPIN

Let's get another drink of water and go back even further, this time to the physics of imparting roll or spin to a ball.

When a putter impacts the equator of a ball moving level thru the back of the ball, and with the putter COG level with the ball COG, the blow imparts all skid and no roll. The roll that eventually shows up is all due to the friction of the grass on the bottom of the sliding ball, making it roll top-forward-down / bottom-back-up. This is not the sort of phenomenon we are looking for, as the "gear effect" imparts spin to the ball solely from the impact dynamics of the relative face and ball COGs in motion and the reaction of the face and ball. For a blow to impart spin of some sort (not resulting from skid), the blow needs to be such that the COG of the instrument moves not thru the center of the ball but above or below the center.

A blow of sweetspot-thru-sweetspot level with no loft produces all skid and no roll. Any roll that eventually shows up comes solely from friction of the grass on the bottom of the ball causing the ball to roll more and more until the rolling speed matches the translational speed, and then there is no more skid. For the blow itself to impart some "early" roll not dervived from the grass "sliding friction," the blow has to "torque" the sphere of the ball. This means a blow directed above or below the ball's COG.





The relevant physics is explained in detail in the great little site named The Physics of Pool.

Once the ball is struck, there is an initial period in the roll of pure acceleration up to a velocity of the ball away from the face. Then, the ball is ordinarily sliding across the ground as the "sliding friction" makes the ball start rolling top-forward. Once the rotational speed of the ball increasaes sufficiently to match the translational speed of the ball's COG horizontally across the green, there is no more "sliding friction" and no more "skid" - the ball is only rolling subject to "rolling friction." Rolling friction is somewhere around 1/10th as much as "sliding friction," but it is enough eventually to bring the ball to a gradual stop (on level ground, where gravity is not adding or subtracting forces).

This chart from the Oxford Croquet website shows the three phases of acceleration (very short), skidding-to-rolling, and only rolling.



In fact, there is a final phase called the "decay" phase where the ball's rolling slows to a point that allows the ball to sink back into the grass a little. This increases the rolling friction, and brings the ball to a halt a little quicker. Slow greens have more "decay rolling friction" than fast green. Indeed, slow greens have more "sliding friction" and more "rolling friction" in general, so putts on slow greens have a quicker skid phase, not as long a rolling phase, and a more abrupt decay phase.

This chart shows the "knee" where the decay phase onset occurs for various green speeds:



The "knee" is around 9-10 feet out in this 11-foot putt.

The function of back spin and top spin in all of this is to shorten or even prolong the skid phase. In general, back spin makes the skid phase last longer, while top spin makes the skid phase end sooner. Altering the ball-green friction at the outset of the roll can also affect the length of the skid phase.

When the putter COG is low, does the higher ball COG knock the putter face top-back? It seems that the shafting and hoseling would likely resist this pretty good, as if the driver had the shaft inserted horizontally into the toe-end of the driver face. That is, the fact that the hosel is attached to the putter face in the VERTICAL plane would seem to cancel or greatly reduce any tendency of the putter face to get knocked top-back. This would seem to be the case even if the putter head COG is recessed back from the face (on the X-axis). If the putter face is not "opening" vertically top-back, there would seem to be no "gear effect" at all. Perhaps I am wrong about the flexibility of the shaft-hosel-putter head assembly. If so, then putter shaft flex should be a great big issue.

If the putter face is moving "level" thru the ball, it is worth noting that a "loftless" face presentation to the ball would necessarily impact the ball on the equator. In the vertical look at the profile of the back of the ball, the equator is closest to the putter face of all parts of the ball. In order for a putter face to be lofted but moving level so that the point of impact on the ball was actually above or below the equator, the lofting (positive or negative) would have to be pretty severe, slanting the leading edge of the tilted face sufficiently that the putter face first comes in contact with a point on the back of the ball not as near the face as the equator. In order to hit the back of the ball on a point below the equator, it is necessary as a practical matter to move the putter not level but upwards into the lower back quadrant of the ball. Similarly, in order to hit the back of the ball higher than the equator, it is necessary as a practical matter to move the putter not level but downwards onto the upper back quadrant of the ball.

Let's try something else. Suppose the putter face is NOT moving level thru the ball, but instead is moving on a rising trajectory with the face COG curling up and passing thru the ball's COG. Assume further that the rising trajectory does not add dynamic loft to the face at impact, but the face is vertical and parallel to the line in the ball from top of ball to bottom of ball on a level green. In this case, there would still not be any "gear effect" as in a driver. In a driver, the face of the club runs toe-back and center-out in a clockwise face turning that slides outward across the back of the ball to give hook spin. And the path of the driver COG does not pass thru the ball COG, but inside it. The putter-ball impact here envisioned would seem simply to launch the ball along the rising trajectory of the face COG, but not otherwise impart overspin -- just a dead-ball punch upward off the ground a bit.

So how do we configure a putter face-ball impact in order to give the ball overspin? The first question is why does a normal putter give the ball backspin?

A "normal" putter has about 3 degrees of loft. Assuming the lofted face is moving level thry the ball with face COG level with ball COG, what happens? It seems the point of contact would be on the equator of the ball, but then the ball would start to slide or roll up the face of the putter because of the 3-degree tilt top-back. And from a vertical perspective, back spin is slice spin. So it's fairly easy to see how positive loft creates back spin.

But, as soon as the ball slides up the face, then we have the scenario of the driver "gear effect." So why doesn't loft create "gear effect" hook spin, or does it? The face COG is moving inside, the ball COG is outside, and the face is "open" top-back in a slice (upward) presentation to the ball - just like in a driver "gear effect." So far, we have slice spin (back spin vertically). The "gear effect" giving hook spin comes about only when the face COG moves upward toward the ball COG away from the ground (on the Z-axis). Does it? This is where I think the vertical hosel comes into play to reduce or eliminate this action. By preventing the face from "opening" more top-back, the only way the face COG can move up across the back of the ball is for the whole putter to rebound vertically. This is opposed by the golfer's whole body extending the putter downward to the ball.

Does negative loft reduce backspin or impart top spin? Assuming a level blow with a negative-loft face (top edge of face tilted ballward), the ball could not slide down the face because it is already on the ground and there is no more "down" to go (except punching the ball into the turf). Apparently what happens is that the face initially hits the ball's equator, forces the ball a little into the turf thus lowering the ball COG below the face COG, and redirects the impact dynamics so that the face COG is moving level thru the upper quadrant of the ball. This is something of a glancing blow with a little less energy than a flush face-sweetspot thru ball-sweetspot impact trajectory. But it would seem to reduce back spin and increase top spin.

What role does having the COG recessed back from the face play? This is one of the key features for driver gear effect. But in the putting stroke, I believe that the recessed COG really just means that face impact occurs while the putter COG is in a retarded phase of the putting arc, not yet rising as much as the face. So having the putter COG recessed is just a way to get a lower start up thru the ball than otherwise. If the path of that recessed sweetspot cuts upward thru the ball higher than the ball's COG, perhaps that's all that really matters.

All that said, it seems to me that the only real way to get topspin is to have something of a glancing blow in which the face COG is not moving on a trajectory thru the ball's COG, but is instead moving either up from the lower back quadrant on a path higher than the ball COG or moving from the equator on a path that takes the putter COG higher than the ball's COG or moving thru the top quadrant of the ball on a path higher than the ball's COG. It's all about the path of the face COG staying above the ball's COG.

This explains to me why Harold Swash teaches a hands-ahead rising blow thru the ball that presents the face "tangentially." On any point on the surface of a sphere like a golf ball, there is a direction aimed at the center of the ball (it's COG), and a "plane" that rests on the outter surface of the ball at this point is a "tangent" plane when the plane is perpendicular to the radial line aimed at the center of the sphere. I gather that Harold Swash is referring to the putter face matching this tangential plane on the ball at impact. That explains the hands-ahead delofting the putter so the face can match the tangential plane on the ball. The delofting also implies that the impact point is either on the equator or the top quadrant of the ball, but not the lower quadrant. The rising blow implies that the path of the face COG is moving thru the ball higher than the ball's COG.

Personally, I believe that reducing the back spin and increasing the top spin can be done without the hands-ahead delofting of the putter and a top-quadrant blow. By simply moving the putter's COG up thru the ball on a path higher than the ball's COG, the objective is accomplished. This can be done without the hands-ahead delofting by using a normal pendulum stroke with dead hands and ball position well forward of the bottom of the stroke that presents the face of the putter to the back of the ball when it is rising AND on a path that takes the putter COG up thru the back quadrant of the ball and out thru the ball higher than the ball's COG. Keeping the loft to a minimum would reduce launching the ball in the air, and negative loft used in this sort of impact probably helps the top spin.

In conclusion, I'm not convinced that the true physics of back spin and top spin have been propely described. I believe it is the PATH of the putter sweetspot thru the ball, and not so much the "gear effect" or even the "cue stick" type blow.

This brings us back to the underlying issue that has not received sufficient attention -- whether back spin or absence of top spin matters? If we have to craft a stroke so carefully that the trajectory of the sweetspot of the putter has to fall within a very narrow range or possible trajectories, is it worth all the trouble?

Skid robs a ball of energy, and so the stroke doesn't send the ball as far as it would otherwise. Who cares, so long as the ball gets to the hole? One can become very proficient and have great touch even though the ball skids a lot, so long as the technique is consistent and the skidding is consistent. The real question is whether the skid does something worse to the putt, like send the ball off line or make it hop. I've never seen a study about this.

It stands to reason that a skidding ball is "more violent" in a sense than a rolling ball, and a more "violent" ball is more likely to do something unwanted. Maybe so, but how likely? Is the reward of not worrying about true roll worth the risk of the ball running seriously off line? I don't really know, and so far as I can tell, neither does anyone else.

The C-Groove testing does conclude that a shorter skid phase and a more accurate holding of the line go hand in hand. According to robotic tests, the C-Groove has a 3-inch skid versus the typical 18-inch skid for most putter designs (factor of 6), while the C-Groove has a mere 1-inch dispersion over a 50-foot putt versus a conventional design dispersion of 3 inches (factor of 3).



Unfortunately, the exact trajectory of the putter COG thru the ball is not indicated.

Assuming that a "truer" roll is worth the price of extra trouble and fragility in the technique, I would suggest the simplest technique to improve the roll and reduce the skid is the best technique. For this reason, I prefer ball position and dead hands rather than forward pressing loft out and then impacting the ball with hands-ahead and perhaps a descending blow as well (too complex).

With this approach, then, whether a high-COG or low-COG is better is anyone's guess. I suspect that a high-COG with little positive loft used with dead hands and a rising blow is safer to make sure the putter COG stays above the ball COG on its way thru the ball. But I have to say that only carefully designed high-speed camera work that carefully accounts for the trajectory of the putter COG thru the ball is likely to get this sorted out properly.

We'll get it figured out one day. In the meantime, I'm not convinced that "true roll" is worth all the bother. Just play the ball well forward of the bottom of the stroke, use a simple stroke technique, and use a slow tempo without "percussion" against the ball. Keep the violence out, and that's probably good enough until we know more.

Cheers!

Geoff Mangum
Putting Theorist and Instructor
Geoff Mangum's PuttingZone
http://puttingzone.com
Golf's most advanced and comprehensive putting instruction.

Over 600,000 visits and growing strong ...

518 Woodlawn Ave
Greensboro NC 27401
336.230.0612 home
336.402.1602 cell



    
This message has been edited by aceputt from IP address 172.209.39.217 on Mar 11, 2004 5:17 AM


 
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John McHugh
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24.147.132.6

Your COG Analysis

March 19 2004, 9:48 PM 

Enjoyed your COG analysis. Though it was somewhat over my head, I think I got most of it.

I just got a futura and have had great luck with it on the rug (I live in Boston). I caught the "cup" 8 out of 10 @ 14 feet. I'm playing the ball a bit forward and trying to use 'a quiet eye'. Do you feel the ball placement is helping or should I go back center the ball at address?

I'd appreciate any advice you might have.

Thanks

John

 
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Geoff Mangum
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172.172.211.27

Not Much Experience Here with Futura

March 20 2004, 7:40 AM 

Dear John,

I haven't swung the Futura putter all that often, but I seem to recall a sense that the hosel attaches to the putter head well in front of the COG, which makes it a little different from a conventional design, and more like a gooseneck putter.



This design probably shifts the bootom of the stroke arc a bit forward, so that when the COG is bottoming out, the hands and putter face and hosel are all forward of that bottom in the middle of your stance a bit. This all suggests to me that a ball position forward of the middle of your stance and inside your lead-side heel (assuming a stance about as wide as your shoulders) is probably fine. Too far forward of that would probably make the putter have too much loft at impact, and a little back of that (just a little) is probably still ok. So the range of choices is somewhere between about 1 inch ahead of the middle of the stance to about 3-4 inches ahead of this point -- probably favoring the 1-2 inch part of that range. Just a guess. You'll have to experiment, but I am suggesting the hosel-COG relation will influence the final pick.

Cheers!

Geoff Mangum
Putting Theorist and Instructor
Geoff Mangum's PuttingZone
http://puttingzone.com
Golf's most advanced and comprehensive putting instruction.

Over 615,000 visits and growing strong ...

518 Woodlawn Ave
Greensboro NC 27401
336.230.0612 home
336.402.1602 cell

 
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Simon
(no login)
203.118.173.121

Re: Path of COG - not Height - is Probably Key

April 1 2004, 6:47 AM 

High Jeff

Damn you have tapped into my mind from USA to New Zealand

ie your words " Skid robs a ball of energy, and so the stroke doesn't send the ball as far as it would otherwise. Who cares, so long as the ball gets to the hole? One can become very proficient and have great touch even though the ball skids a lot, so long as the technique is consistent and the skidding is consistent. The real question is whether the skid does something worse to the putt, like send the ball off line or make it hop. I've never seen a study about this.
"

IMHO There is more marketing nonsense spoken about this area than any other area in putter design!

Cheers

Simon

 
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Chuck
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66.82.9.29

Hi Simon Still Alive??

May 18 2004, 5:42 PM 

HI Simon

How is the new belly putter coming is it on the market yet?

Just wondering

Good Luck

Chuck
American Putter

 
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Dr Norman Lindsay
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80.3.0.40

Re: Path of COG - not Height - is Probably Key

May 12 2004, 10:01 AM 

Skids, Squirts & Scandals


Dear Geoff,

I recently found your essay entitled Path of COG - not Height - is Probably Key. You state that there must be some basic uncertainties in the definitions or understandings about the underlying physics of this subject.

On the contrary, I know that the physics is well understood, certainly well enough to decide whether low or high COG generates more or less topspin. There is a wealth of good experimental data that proves the accepted theory.

A year ago I sent you a draft copy of my paper Topspin in putters a study of vertical gear-effect and its dependence on shaft coupling (Lindsay 2003). This paper gives chapter and verse on the subject of putter weighting and topspin and also presents significant original research on how the shaft affects clubhead rotation at impact. It describes new techniques for measuring spin performance and some results of these measurements are published, including data from the C-Groove putter and the Odyssey 2-ball.

Your reply to J P Vegas is a tour de force, and I admire your obvious enthusiasm for the subject, but the guy just needed the right answer and not a choice of three!

Lets start with your Camp 2, i.e. locate the putter COG high on the face and replicate what happens when a cue stick imparts top spin to a cue ball in billiards

For the record - a small correction. Striking a ball with a cue at height 7/10ths diameter eliminates skid (Daish 1972).

However, simply elevating a putters COG above the ball equator to 7/10ths diameter does not achieve the same effect as the cue stick in billiards or pool. Its impossible to contact a golf ball at a height of 7/10ths diameter with the face of a legal putter unless you are hitting down or otherwise de-lofting the face very severely. At 7/10ths diameter, the tangent (i.e. the slope of the balls surface) is -23.6 degrees to the vertical but the R&A and USGA have put a limit of 15 degrees on the permitted amount of negative loft in conforming putters.

Even if you did hit the ball with a -23.6 degrees negative loft putter face, you would not get the ball to roll without skidding. Initially, the ball would dig into the putting surface at an angle of about 20 degrees and, yes it would have some topspin, but probably less than a quarter of true rolling spin. It would then undergo a severe and abrupt skid, probably jump into the air, and its anyones guess what spin it would have after that.

YOU CANNOT INVOKE MATHEMATICS FROM POOL OR BILLIARDS TO EXPLAIN GOLF IMPACTS. The only instance where this is valid is for direct central impact.
There are huge differences between a billiard cue and a putter or any other golf club. The soft leather tip on the cue plays an important part but there are other obvious differences between the two implements. This is something I will attempt to explain in more detail at some future date on my website Lindsay Putters.

Meanwhile, to whet your appetite, have a look at these clips from a really good website for pool physics:

http://www.engr.colostate.edu/~dga/pool/normal_videos/NV4-13.htm> (Squirt due to high speed English)

http://www.engr.colostate.edu/~dga/pool/high_speed_videos/HSV4-4.htm> (High speed English close up)

The first clip is an elevated view of a cue ball demonstrating high speed left English where the ball is struck left of centre to give it clockwise spin (in plan view). The remarkable aspect of this sequence is that the deflection to the right, or squirt, is really quite small. If, instead of a cue, the ball was struck by a putter swung along the line of the cue stroke and with open face to hit the left side of the ball, the ball would get pushed to the right cushion and not go almost straight along the swing path as it does in the clip.

The second clip shows a close-up of the stick-on-ball impact in slow motion a brilliant demo. View this with zoom at 200% (right click to get zoom). Here, the cue stick hits the ball off centre at about 7/10ths diameter from the right edge and sure enough the ball rotates roughly 220 degrees over a distance of about two diameters, which approximately equates to the no skid at 7/10ths impact scenario. Also, note the momentary jump of the cue tip to the left very revealing.


Now to Camp 3. COG-to-COG Level

You cite the T-Roll Putter as a design in which the putter COG is the same height as the ball COG. I had a quick browse through the T-Roll website and, despite other nonsensical claims (e.g. 'Pushed' or 'Pulled' putts create sidespin on the golf ball and cause the golf ball to 'spin out' of the hole unless the golf ball hits the cup dead center), I could not find any claim that the T-Roll imparts topspin, so it is not really in contention.

However, delving into the origins of the Aserta Putter, I discover that the original science behind this novel putter is as follows

The club has a raised center of gravity intended to be in alignment with the center of a golf ball.This allows the club to strike the ball in a manner similar to a pool cue. In other words, forces transmitted to the ball along a horizontal line, parallel to the ground, which would go through the center of the ball. This imparts to the ball a forward rolling motion, without topspin. (Bonneau 2002)

I interpret the above extract from US Patent No. 6,383,089 as meaning that a horizontal strike on a ball with a pool cue right on its horizontal equator imparts immediate pure roll without over-spinning.

This is dangerous territory. There are a number of highly respected physics websites, not to mention a wealth of literature from Sir Isaac Newton onwards, that describe how under these impact conditions the ball skids until its linear velocity reduces to 5/7ths of its initial velocity before rolling. The over-spinning or topspin in US 6,383,089 is what you would expect from hitting a cue ball above 7/10ths diameter with a cue stick.

US 6,383,089 is a typical example of how patents are granted despite the invention being based on principles that are contrary to the known laws of physics. (In the above case, the law of conservation of angular momentum.)

Now, I have no doubt that some golfer swear by the Aserta (and dont even need to be paid to do so). They may be really convinced - and in some instances may actually experience - that it provides game improvement. But would the majority of Aserta buyers still be convinced of its amazing benefits if they knew it creates more backspin than a traditional, low COG putter? How many golfers have been duped by the Aserta website animation showing Immediate True Roll , thinking that this is the real McKoy and not realising that it was created by a graphic artist and bears absolutely no semblance to reality? This is all part of the scandal that pervades putter manufacture and putter marketing.


Now for Camp 1 LOW COG FOR "GEAR EFFECT"

Karsten Solheim, the founder of modern putter design, advocated maximising the weight low in the putter head to improve overspin at impact (Solheim 1995). His pioneering ideas, dating back to 1959, have since been copied and adapted in countless putter designs. So its not unusual to find lots of putters that more or less provide low COG, but your selection of examples of low COG putters is strange. Why the C-Groove Amy model is an example of concentration of mass low on the back flange is a mystery.

ontic.jpg
Your next example, the Ontic is even more surprising. Here you see a conventional putter body raised off the ground on two sliders or rails. How in the name of all that is wonderful does this lower the COG? It does the complete opposite. The bottom surface of the rails determine how low the body of the putter-head can be positioned relative to the golf ball. Therefore, the bottom of the rails form the datum from which the height of the COG is measured.

You are correct to question that Camp 1 and Camp 2 are completely contradictory but your conclusion that the Aserta data just deepens the mystery skirts round the really big issue in all this, namely, the habit that putter manufacturers have of lying shamelessly about the technology of their designs. In the case of Aserta, the invention is undoubtedly based on wishful thinking rather than deliberate deception. (After all, its been patented WOW!) However, the data they publish, while appearing to be better than competitors, goes nowhere near supporting the immediate true roll theory.

Incidentally, when is someone going to tell them that 2.216 inches is NOT the circumference of a standard regulation golf ball?

So how do some manufacturers demonstrate their putters giving more roll than the competition? The answer is, they show their putters giving earlier roll by simply arranging a flatter launch trajectory. This is shown in the following frames of video footage of the C-Groove putter, which claims to impart immediate pure roll (where have we heard that before?) by virtue of its unusually shaped grooves

CGroove_Video1.jpg
FRAME 1 Note the C-GROOVE putter-head (lower picture) is about 3 inches behind the zero mark on the scale.





CGroove_Video2.jpg
FRAME 2 The ball struck by the OTHER brand putter is off the ground you can see this from the shadow it casts. This ball is slowly spinning in mid-air with a combination of slight backspin and sidespin imparted by the putter impact.

Meanwhile, the C-GROOVE ball has already landed on the ground because its launch trajectory angle is one or two degrees lower. It is therefore skidding and at the same time picking up forward roll, which obliterates its initial launch spin. Note that the C-GROOVE putter-head has swung through 7 inches from FRAME 1 (-3 inches) to FRAME 2 (+4 inches).


CGroove_Video3.jpg
FRAME 3 The ball struck by the OTHER brand putter is still just off the ground and has continued to rotate slowly in mid-air with its initial launch spin. As soon as it touches the ground it will start to pick up forward roll, just like the C-GROOVE ball.

The C-GROOVE ball continues to skid and so starts to rotate faster.

Note that the C-GROOVE putter-head has only swung 3 inches between FRAME 2 (+4 inches) to FRAME 3 (+7 inches). A putter-head decelerates slightly during impact but typically by only 20% or so and not by nearly 60%. Explanation?
THERE IS A MISSING FRAME JUST AFTER IMPACT !!

The video clip tells us nothing about the initial spin imparted on the C-GROOVE ball. The frame that might have given this information has been mysteriously deleted. It does show the C-GROOVE ball starting to roll earlier but this is entirely due to the fact that it also started to skid earlier, so the comparison is contrived and meaningless.

Working in golf technology, you soon realise that putter design is very much the poor relation in golf equipment research and development. Most research expenditure is in metal woods and golf balls, so a telling way of settling the controversy is to have a look at metal wood technology. http://www.bs-sports.co.jp/english/basic_of_golf_club/basic_of_club_5.html> (Basics of golf club design) is a page from Bridgestones excellent guide to golf equipment design. This gives simple, clear definitions and explanations to non-technical readers. Rest assured, behind every statement is a wealth of knowledge and research. Opening this page and scrolling down to Gear Effect, you will find a diagram illustrating both horizontal and vertical gear effect in a metal wood club, and there we see

Bottom of the face = more backspin
Top of the face = less backspin


In a lofted metal wood club the predominant ball spin is backspin but for impacts on the top of the face, gear effect generates a component of topspin (shown in the diagram), which reduces overall backspin, while the vertical gear effect generates additional backspin for impacts on the bottom of the face.

One thing that you wont find in the Bridgestone site is discussion of how the shaft affects gear effect. Until I published my research on shaft compliance modes (Lindsay 2003), the universally held theory was that the effect of the shaft could be neglected during the sub-millisecond duration of impact. This is often referred to as the free body model of club-on-ball impact. You only need to look at some recently published patents describing finely tuned mass and inertia designs of metal woods from some of the top golf research establishments to confirm that the free body model was until recently the accepted wisdom.

I note with interest that you have picked up on my research findings (Lindsay 2003) and use them in your essay as if they are common knowledge. Since this is recent research, it is standard practice and courteous to properly acknowledge the source of your information.


Path of COG - not Height - is this the answer?
Your theorising that topspin is best created by a rising blow so that the path of the face COG is moving thru the ball higher than the ball's COG has some validity but in practice wont work. What you are advocating is similar to getting topspin on a tennis ball. With tennis, the racquet is swung on a steep upward trajectory (e.g. 45 degrees or so) yet the ball is still stuck near the centre of the racquet. Putting topspin on a tennis ball struck from the middle of the racquet is a perfect example of vertical oblique impact a basic concept found in all good dynamics textbooks. It is impossible to achieve any useful degree of vertical oblique impact with a putter. A rising blow with just a few degree of upward attack angle will lift the putter-head to make contact on the lower half of the putter face. This in turn will negate any slight topspin created by the oblique impact.

Have a look at http://www.lindsayputters.com/spinmeasurements.htm> (Spin measurements) on my website. This shows that the higher the putter head at impact, the lower the impact point on the putter face and the greater the backspin. The effect is particularly strong with mallets, which usually have greater gear effect characteristics than blade designs.

I strongly advise that you temper your theorising with experiments and measurements of what actually happens. Science is about making the theory fit the facts and not the other way round. It doesnt take much to replicate the measurements shown on my website and you dont need to have huge budget or a PhD in engineering or physics. Take a look at http://tuhsphysics.ttsd.k12.or.us/Research/ib01/Peyton/physics.htm> (Kyle Peytons experiments).
I dont agree with many of her findings but here is a school kid who shows fantastic determination, diligence and ingenuity in a practical quest to find out what make putters work.

References

Bonneau, M.D. (2002) Inverted Mass Relieved Putter. U.S. Patent Number 6,383,089

Daish, C.B. (1972) The Physics of Ball Games. The English Universities Press Ltd., London, UK.

Lindsay, N.M. (2003) Topspin in Putters a study of vertical gear-effect and its dependence on shaft coupling, Sports Engineering,6(2), 81-93

Solheim, K. (1995) Putter Head Design. In: Golf the Scientific Way, (ed. A.J. Cochran), p. 69. Aston Publishing Group, Hemel Hempstead, UK.




    
This message has been edited by aceputt from IP address 71.71.48.219 on Dec 27, 2013 9:49 AM


 
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Neville
(no login)
144.136.252.222

Wow

May 12 2004, 8:59 PM 

Hi Geoff
As an person interested in the cut and thrust of debate, this is all good stuff. However, in the real world of improved putting at amateur level, it does not matter a darn. The average golfer who comes to me for a putting assessment couldn't hit a cow's backside with a banjo even if he or she had a magic wand and the cow was only 6 foot away. The problems I see are basic such as putter too long, head position out of wack, shoulder alignment skewed, gating stroke path and so on. And this is even before we get to putt reading.
Nevertheless love the debate, even though it can get a touch personal
Nev
Oz

 
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Geoff Mangum
(no login)
172.162.236.218

Wonderful Information

May 13 2004, 8:51 AM 

Dear Dr Lindsay,

I greatly appreciate the time and trouble you have expended in posting some wonderful information! You and I are definitely taking the same basic approach. As your website states:

"Lindsay Golf champions scientific objectivity and tries to clarify important aspects of putter design. Real facts are explained and simple measurement techniques are shown to help illustrate these facts. Future research will look at the whole putting scenario to increase understanding and help golfers to improve and enjoy their game."

Certainly, you have the equipment and training to conduct experiments, where I at present do not. But I do differ a little with you about the relationship of theory and experiment in science. You state: "I strongly advise that you temper your theorising with experiments and measurements of what actually happens. Science is about making the theory fit the facts and not the other way round." Your statement does not quite capture the relationship accurately. The theorist examines experimentally derived data and compares the data to "facts" in search of anomalies, paradoxes, or new questions that require further examination by experiment. If a good experiment provides unassailable proof that a theory is flawed, the experiment has made its contribution. Thus, theory leads experiment, and experiment keeps theory headed in the right direction. Einstein never performed an experiment in his life, yet his theory started with the inadequacies in the then-existing experimental data from Newtonian physics theory to explain the "facts" of light. Richard Feynmann devised the theory of Quantum Electro-Dynmaics (QED) on principles of physics and mathematical grounds to describe with incredible precision the facts of atomic behaviors; when he first visited the Swiss nuclear research center CERN, the experimentalists gestured to the multi-billion dollar equipment and remarked that everything they were working on came from Dr Feynmann's theorising. Of course I am paying as much attention to experimental data as I can, but in a critical, inquiring manner in search of vagueness, contradicition, and lack of clarity. My goal and intent, like yours, is to "clarify important aspects" of putting and to "increase understanding" of the whole putting scenario.

So let's get back to that.

For some quick housekeeping, I would like to respond directly to three statements you make:

1. "For the record - a small correction. Striking a ball with a cue at height 7/10ths diameter eliminates skid (Daish 1972)." I stand corrected. My use of 5/7th is due to the fact that skid always stops once the surface friction has reduced the initial translational velocity of the ball to 5/7th its initial velocity, and I simply confused this for the 7/10th figure.

2. "Your next example, the Ontic is even more surprising. Here you see a conventional putter body raised off the ground on two sliders or rails. How in the name of all that is wonderful does this lower the COG? It does the complete opposite. The bottom surface of the rails determine how low the body of the putter-head can be positioned relative to the golf ball. Therefore, the bottom of the rails form the datum from which the height of the COG is measured." I think I am correct about this. If a level see-saw has weight added to the right side, the COG of the see-saw shifts in the direction of the added weight (to the right). If you add weight to the bottom of a putter as the Ontic putter does with the mass that constitutes the bottom two "runners," this will LOWER the COG of the putter face below what it was before the addition of the runners below all the existing mass.

3. "I note with interest that you have picked up on my research findings (Lindsay 2003) and use them in your essay as if they are common knowledge. Since this is recent research, it is standard practice and courteous to properly acknowledge the source of your information." You also say you sent me your unpublished paper. This may well be true but I don't recall ever having recieved it. I have tried on several occasions to communicate with you since our earliest contact, without reply. (Could you please resend the paper?) In any case, all the information I reference comes from your website, which perhaps duplicates the information in your paper. All my references to your work CLEARLY is noted as coming from you. The suggestion that I do not credit my sources is not very polite, as I work with utmost diligence to distinguish myself as the ONLY putting instructor who is extremely careful to give proper credit where credit is truthfully due, and not to pass off as my own work the labors and ingenuity of others.

Back to the topspin issue:

The whole thrust of my post is that I find the discussion and data by others less than clear, and certainly contradictory. There are two main points I hope we can clarify.

Specifically, I question whether the "gear effect" of the driver really applies to the putter in a wholesale manner or in some modified way. You response only indirectly addresses this point, and does not shed much light on how the "gear effect" really operates with a putter. Does the (vertical) hoseling for putters reduce or perhaps eliminate the vertical "gear effect"? If so, in what way?

Similarly, I don't think your reply to my suggestion about the path of the putter COG moving above the ball COG is very clear. At the moment of impact (and for the duration of impact for the "impulse"), the putter momentum (mass times velocity) is a vector and the direction of this vector thru the ball may be directed above the ball's COG notwithstanding the immediate geometrical relationship between putter face as lofted and back of spherical surface of ball. I don't think a rising putter head necessarily needs to impart "oblique impact" on the tennis raquet model you depict. You write:

"What you are advocating is similar to getting topspin on a tennis ball. With tennis, the racquet is swung on a steep upward trajectory (e.g. 45 degrees or so) yet the ball is still stuck near the centre of the racquet. Putting topspin on a tennis ball struck from the middle of the racquet is a perfect example of vertical oblique impact – a basic concept found in all good dynamics textbooks. It is impossible to achieve any useful degree of vertical oblique impact with a putter. A rising blow with just a few degree of upward attack angle will lift the putter-head to make contact on the lower half of the putter face. This in turn will negate any slight topspin created by the oblique impact."

I gather from this that you are depicting a raquet held so that its hitting "face" is vertical and not tilted or lofted as presented to the ball, and that the trajectory of the center of the raquet is moving up across the level flight of the oncoming ball at a 45-degree angle. The reason you cite for stating that this cannot usefully be accomplished with a putter is that a rising trajectory necessarily means that the point of impact will be on the lower half of the face, and this produces backspin that overcomes the topspin produced by the "oblique impact." This strikes me as unclear and confusing. You seem to grant that the sort of blow DOES impart topspin, but then state that the low-face impact gives backspin that negates the topspin, and so a net backspin results. A normal putting stroke is radiused such that extending the vertical arc of the stroke into a complete circle generates a cirle approximately 9 feet in diameter, and about 55 feet (660 inches) in circumference. The segment of the putting stroke arc that we are concerned with immediately before and during impact is at most 1-2 inches of this circumference, and the rising of the putter face in relation to the back of the ball is on the order of under 1/8th of an inch at the most. This rising of the putter face COG may or may not result in an impact point on the face that is BELOW the putter COG. It depends on where the putter face COG started at the bottom of the arc before it rose a little into impact, doesn't it? And in any event, even if the face of the putter is dynamically lofted a little, combined with the momentum vector of the putter at impact aimed above the ball's COG, then we are discussing whether the ball gets launched off the surface so that the earliest skid is delayed, which in turn delays the early onset of roll, aren't we? Purely in terms of backspin and topspin, what are the relative contributions of putter COG directed above ball COG versus low impact point on putter face (i.e., below the putter COG)?

I much appreciate your time on this, so let me thank you richly in advance for any reply.

Cheers!

Geoff Mangum
Putting Theorist and Instructor

Geoff Mangum's PuttingZone

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Ian Seaders
(Login lloyd06)
84.75.133.121

Putter loft stroke and backspin

December 26 2013, 5:04 PM 

The very best and serious detailed analysis of Gear effect in putting I have come across until now and would seem to correspond to the research done by Rod Cross and Alan M. Nathan from the Physics dept. of Unitv. of Sydney, NSW 2006, discussing gear Effect of golf balls and Clubs.
My understanding of the research and analysis of Geoff's would be to keep the club coming up through the ball and with as little loft as possible, preferable already designed into the putter to keep the stroke simple.
Concidering the research refered to above, it would seem that we should be at least or more concerned about the effect of hitting the ball (while putting) off center on the x and y axis, which will give the ball sidespin. The putter will tend to diflect like a driver, if even in a very minute amount, since it is not an immovable concret wall) . My two bits here are that good heel and toe weighting with a very stiff shaft would be the major design concern here.
Thank you much Geoff for the very understandable analysis of COG and putting.
Ian Seaders
Switzerland

 
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Zachary Smith
(Login Cleek5)
64.231.129.92

Re: Path of COG - not Height - is Probably Key

February 25 2015, 3:03 PM 

Sorry, but I feel this is a load of Hooey. If you watch any infomercial they always
demonstrated other brands with video, but, computer graphics for their brand.
I prefer a hard smooth shiny putter face to impart the least amount of miss direction from a pulled or pushed path.

 
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JPVegas
(Login JPVegas)
217.43.8.153

Thanks for the information

May 15 2004, 10:47 AM 

Dr Lindsay and Geoff:

Thank-you both for the wealth of information that you have provided on putter weighting and top spin. It is going to take a while to digest the information, but I think the information is worth looking at closely.

Dr. Lindsay: Where can you purchase one of your putters. I keep checking your website and I can find information on the putter, but not where to purchase.

Thanks again.

 
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Chuck
(Login Putterman)
66.82.9.29

Hung up on COR.MOI Back Weight etc

May 15 2004, 12:51 PM 

Hi Geoff

At the end of the day does it matter if a putter has a High COR, Low COR HI or Low MOI if it is back-weighted, counter balanced, Face balanced, Toe balanced, Upright, Flat, Long or Short??

It seems to me that you have to first see the line, Second determine the speed and third practice until you can do both well.

In spite of all the "NEW PUTTER DESIGNS" the 40 plus year old Cameron design is still the number one putter on tour. My own design is starting to catch on and players on all the tours are giving it a try.

Seems to me that if you can find a putter that you like and then put in the time on the putting green you will get better. No matter what type of putter you use. Golfer are always looking for a magic bullet that will cure their failure to put in the time needed to get better.

Your brief thoughts are as always welcome

Chuck
American Putter


 
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Eric Letson
(no login)
24.128.81.32

The answer to your question.

January 7 2005, 1:38 PM 

Greetings,
Geoff’s message was right on cue; however, I would like to simplify it a bit.

Low COG putters have been around for ever and for good reason, they work. There are good ones and bad.

High COG putters like the FeelTech Golf EV1 Series are a new breed of putters on the market that do impart significant topspin upon impact. This is the next evolution in golf and those that are not on board now will be playing catch up for years to come. But again, there are also good topspin putters and some very bad. The problem with topspin putters is unless you have a high attention to detail as a manufacturer, you find yourself with a putter with a closed face from the vertical at impact, this forces the putter to come down on the ball and creating a popping effect. This ultimately bounces the ball off line and of course that is not the desired result. Another problem is weight, top spin putters must weigh more in order for their mass to do what it says it can.

For example. FeelTech Golf (my company) has created the EV1 Series putter (forgive me for sounding like a commercial) which is 37% heavier than a typical putter. This added weight gets you through the ball and eliminates stabbing the ball that is all too common with low COG putters. We had experimented with lighter titanium, but at 17% lighter than a typical putter, the ball just popped off the face.

We have a putter that performs exactly as we designed it. With the COG being at .851 which is slightly above the equator of the ball, we start by a nice true roll every time, even on miss-hits, plus with our patent pending Dome technology, we have a putter that stays square at impact and through the putting stroke.

As a result, you have to try our putter to feel the difference. Ultimately, putting is a game within a game and no two people putt the same or feel the same thing. Feel is something that is not tangible or explainable; it is just something inside that each golfer has to find on their own.

Remember to stroke the putt, not strike the putt and "ENJOY THE GAME".
Regards,
Eric Letson
Founder/President
FeelTech Golf, INC
www.feeltechgolf.com





 
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Geoff Mangum
(Login aceputt)
Owner
71.71.48.219

Topspin Not Very Useful

December 27 2013, 10:00 AM 

Dear Ian,

I am thoroughly familiar with Rod Cross' physics papers available on the web, and they are pretty good, except he is not too familiar with actual putting.

The MAIN thing about topspin in putting is that it is not a very valuable goal. The DIFFERENCE in the initial forward- or backward-spinning state of the ball off the putter face at impact between a "good" putter design and a "bad" putter design is almost ALWAYS eliminated by the grass and it's "forward roll inducing friction on the bottom of the skidding ball" within the first two or three inches of every putt.

So you are right that a) launching balls into the air at impact and / or b) imparting sidespin at impact are the other two aspects of putting to guard against.

As to sidespin on a ball, however, this causes two forces that deflect the ball's line:

1. the friction beneath the bottom of the ball spinning in the plane horizontal with the surface (like a "top" spinning on its point) creates in the total area of contact of the ball and the grass (a shallow bowl-like area at the bottom of the ball) a high-pressure side and a low-pressure side that operates for a brief time until the forward-rolling friction cancels this out -- a right-hander's cut-spin has the ball spinning clockwise looking down on the top of the ball, with the high-prtessure side on the left of the ball's direction of travel as the left bottom of the ball turns into the grass, while the right side turns away from the grass, very similar to the air pressure of a slice spin in the air; and

2. wobble of the axis of rotation, which injects some chaos into the roll that usually but not always causes line problems, and also "wastes" energy of the roll so that the distance is a bit less than expected.

The side spin in putting is NOT the same as side spin in bowling. In bowling, the spin is in the manner of a bullet, with the axis of spin oriented horizontally to the surface and perpendicularly to the direction of travel. This is why bowling balls (America) have holes for the fingers, so the fingers can give pronation spin on release, which is counterclockwise spin seen from the back of the ball. The forward-rolling friction does much less to reduce bowling "bullet" spin than it does to reduce the offline effect of "spinning top" side spin of a putted golf ball.

The grass ALWAYS converts the worst-case "bad" putt into a best-case "good" putt in fewer than two or three inches right at the start of the putt. Since that is when the ball has the greatest velocity and momentum, any deflecting forces in the grass that might differentially deflect a "bad" topspin ball more than a "good" topspin ball are entirely nugatory!

My experience is that launching and side spin do more damage to putting that "bad" topspin off the face of the putter, and that "good" topspin adds practically nothing of value to the putt, since the grass almost immediately corrects the "bad" topspin to the "good" topspin regardless of the design of the putter or the specialness of the stroke. Once the ball has it's initial spin state off ANY putter face and the ball engages the grass friction (only after any launching in the air is over), the ball's ensuing spin-state changes are not up to the putter or stroke any more, and it's just a matter of any ball and the grass. Slow, shaggy grass with much friction converts the "bad" to the "good" quicker over a shorter span, so that applies to almost all amateur golfers who DON'T play on fast, slick surfaces like the Tour venues, which again reduces the value of special efforts to generate extra "topspin" for the vast majority of golfers. And in the case of Tour players on carefully manicured, fast and true surfaces, there is another reason going for "topspin" is not as important as widely believed -- even though slick surfaces takes a bit longer to convert "bad" to "good", it's still not a long span AND there is less danger of the surface causing problems during this "bad" transition span to "good" because these Tour surfaces are especially "true", i.e., not having lots of irregularities in the short span that could disrupt the momentum of the ball at it's very start.

And once the "bad" ball's not-so-good forward spin off the putter face has been converted by grass friction to a forward-spin state that matches that of the "good" ball, the two balls experience no meaningful difference in how they are affected by the grass for line or distance.

So, does topspin make much difference to putts for line and distance? No. Should the golfer spend money chasing improved topspin off the putter face? No. Does a putter that has the usual not-special design work as well as the special design to impart more topspin off the putter face? Pretty much yes.

Should the golfer practice a special stroke technique that supposedly imparts more topspin off the putter face? No, it makes next-to-no difference to line control or distance control.

Of course a golfer wants a consistent stroke used with a putter that does not unnecessarily launch the ball off the ground or impart sidespin, but after that, paying for topspin off the putter face is not really worth all the hype. As to a topspin stroke method, a basic pendular stroke with any slab of metal stroking slightly up thru impact with a square face will give enough modest spin off the face that the grass will clear up any problems pronto, so no special stroke setup and movement needs to be grooved over several decades! Just not real.

A golfer who CONSISTENTLY imparts so-called "bad" backspin off the face of his or her putter can have better distance control than other golfers with "good" topspin. Distance control is about controlling YOUR dynamic, and that works even with backspin strokes and putters.

The first two or three inches of putts that change "bad" to "good" just don't have real or significant effects DIFFERENT on line or distance.

Dave Stockton Jr. was asked by Taylormade to come to their Carlsbad, California, MATT lab to make a commercial to sell their newly designed ASGI (Ant-Skid Groover Insert) putter face technology. The theory of the ad was that Stockton has practiced for forty or more years to learn how to stroke the ball to impart more forward-spin off the face of the putter than anyone, and the new ASGI putter will improve even his forward spin. So they filmed Stockton making two test putts: one without the ASGI putter face and one with. The first one had fabulous forward spin off the putter face, but the second one had even more (perhaps a few percentage points more, not all that much really). In the after-test chit-chat between Stockton and the MATT lab technician who was taking the data, Stockton was complimented on his stroke and beamed in response, "Yes, when I put my stroke on the ball, it really rolls out for distance." The MATT lab technician glance down at his clipboard of data, looked up, and said flatly, "Not really." Stockton was stunned, and cocked his head to the side slightly with a puzzled look in his face, and asked plaintively, "Really?" And the MATT lab technician again consulted the data on his clipboard and repeated, "Not really. Your stroke's topspin might make a difference in avoiding or reducing left-right dispersion off line, but we don't currently have the data that resolves that question."

Neither Dave Stockton Jr. nor the Taylormade MATT folks seems to register the significance of what they had just said. Stockton's forty-plus years of grooving a special topspin stroke doesn't matter and never has. And the Taylormade investment in the research and development of their ASGI putter face ALSO doesn't make any difference to golfers putting, either, since the only two aspects of the putt that matter at all are line and distance control.

The funny thing is that the MATT folks don't seem to know physics about forward roll, skidding, and conversion of the ball's spin state to complete skid-less rolling. This is testimony to the general golf culture's rather amateurish, dilettantish POOR science that blinds so-called "golf science" people from actually looking at the real physics and then actually looking at their own data or the data of anyone else.

Golf culture BELIEVES in "topspin" and golf putter manufacturers SELL "topspin", but unfortunately topspin's value to line or distance control is little more than an "urban myth." All the science recorded in all the videos of the first few feet of putts always shows the same fact that people believing in topspin never notice -- it doesn't matter enough to spit on.

ALL videos of data of ALL putter companies and ALL so-called "golf science" people reveal EXACTLY THE SAME REALITY: Bad spin-state 1 matches good spin-state 2 after the "bad" ball's first few inches on the grass -- all videos record this, but none of these folks ever see it in their own data. Instead, they create stupid definitions of "topspin" (e.g., the total distance off the face before complete rolling begins, which INCLUDES the time the putters launch balls into the air) and dream up criteria for calling the DIFFERENCE between the "good" putter or stroke and the "bad" putter or stroke the way they want the story to end. That's just incredibly BAD SCIENCE.

That's why Taylormade "skipped over" this fact when the technician reported it to Stockton. And of course Stockton hasn't changed his belief that his forty-years-in-the-making stroke is "special" and "important". They should have known that topspin doesn't matter enough to bother with before designing and investing in the ASGI design, and they also should have realized that their data proved just this. But they don't get it, because general golf culture is like a tribe of "flat earthers" wo don't like dissension in the ranks.

Topspin off the face of the putter CAUSED by the stroke or the putter design just doesn't make enough difference to any real golfer to matter. Launching balls and imparting unwanted side spin matter some and enough to matter, but topspin does not.

Cheers!

Geoff Mangum
Putting Coach and Theorist
PuttingZone.com

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This message has been edited by aceputt from IP address 71.54.49.31 on Apr 30, 2015 4:23 PM


 
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Craig
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211.26.94.158

Putting topspin

December 27 2013, 8:12 PM 

While topspin may provide a truer roll ,Has anyone even considered how softly you would have to hit a ball with topspin on a 13 stimp green with a downhill slope in your path ... lol.

 
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Eric
(Login Wala0003)
206.15.203.10

How much it matters

February 5 2015, 12:18 PM 

Geoff, thanks for your in depth analysis. I agree with a lot you say, but I want to take part of what you said and ask what you thought. Basically your last statement of 'Launching balls and imparting unwanted side spin matter some and enough to matter'. I think while a proper stroke is magnitudes more important, I think there is something to topspin strokes and topspining putter designs. Not because the topspin itself is super important, but because the stroke that produces some topspin avoids or lessens the amount of sidespin. And while I don't question the fact that within a few inches, the grass interaction has taken over, I wonder what affect that tiny bit of sidespin could have. I am trying to consider what happens in that 'few inches'.

It would be interesting to calculate the degree that sidespin could affect the angle off the intended target line. Even if it was just a third of a degree on a 15 foot putt you are offline by nearly an inch at the hole. Take two off center strikes, both applying the same amount of force to create some side spin. The only difference is one is hit with more of a topspin stroke. What this does is creates two balls with different spin axes, and what then happens in the first few inches of grass interaction must be slightly different.

In many peoples experience, while they may not know why, some putts just seem to 'hold their line' better than others. Maybe it is just that in the first few inches of being on the grass, some putts are just more online to where they intended their putt to go. And maybe with a topspin stroke a higher % are not affected as much by unwanted sidespin grass interaction, or put another way the topspin stroke causes off-center strikes to not be as ineffective.

 
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Geoff Mangum
(Login aceputt)
Owner
71.54.49.31

"Seems" is Indeed the "Word"

April 30 2015, 4:38 PM 

Dear Eric,

When certain putts "seem" to hold the line better, golfers attribute this rather ignorantly to so-called "true roll". The real CAUSE has mostly to do with hopping and skipping, not true rolling. All balls roll "true" (only rolling, no skidding) once the initial velocity off the face is slowed to 70%. ALL. As in NO EXCEPTIONS. This has ZERO to do with special strokes or special putter designs. ALL putts are rolling true whenever the grass slows the ball to 5/7th (70%) the initial velocity off the face. This usually happens within about 15-20% of the total putt length, and on a 10-footer, that is 1.5-2 feet. So if you are blaming a ball's not really "holding its line" as perfectly as hoped in this 1.5-2 feet initial span, THEN I FURTHER tell you nothing is making any difference from "true roll" after the first 2-3 INCHES.

What SEEMS to be the case to GOLFERS without much science or even tons of logic or common sense is what "gets legs" in the herd-think culture.

The degree that sidespin adversely affects putt direction or distance HAS been quantified by science data-taking by Werner and Grieg, How Golf Clubs Really Work and How to Optimize Their Designs, where they said sidespin doesn't matter. Not enough effect to care about. (Page 152). "The fact is that sidespin is quickly eliminated by sliding friction on the grass in the early part of its travel. "The deviation of the ball travel from a straight line [due to side spin] is so small it is almost imperceptible."

Despite all the points laid out for your consideration above, you STILL maintain that true roll makes a significant difference. Without being or intending to be offensive, it is really necessary to say that opinion isn't worth much.

Cheers!

[linked image]

Geoff Mangum
Putting Coach and Theorist

PuttingZone.com -- over 200 Certified PuttingZone Coaches teaching in 21 Countries Worldwide and growing strong!
The best putting instruction in the history of the game -- integrating the Four Skills of putting (reading, aiming, stroking for line, and stroking for delivery pace) by combining all putting lore in history with modern science for physics, anatomy, physiology, biomechanics, motor sports teaching and learning and performance, and especially the NEW brain science of the non-conscious processes of perception and movement action in putting skill.


    
This message has been edited by aceputt from IP address 71.54.49.31 on Apr 30, 2015 4:49 PM


 
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Frans
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82.236.98.68

The movement not the roll?

July 4 2015, 5:47 AM 

Could it be that the putting movement manipulation needed to generate "earlier" roll (forward shaft lean and positive Angle of Attack) limits or even blocks other possible (unintended) movement manipulation and hence generates a more constant putting stroke?

I mean that maybe it's the roll that is given credit for the improved putting while in reality it's the needed manipulation that generates a more consistent movement.

 
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Geoff Mangum
(Login aceputt)
Owner
71.95.221.26

Unintende Improvements

July 12 2015, 2:19 PM 

Dear Frans,

That's a very astute insight.

I agree that some "putting techniques" sold as supposedly accomplishing "improvement 493" do not really help the putting because "improvement 493" is either not real or insignificant (and sometimes even the technique does NOT have anything to do with "improvement 493"), BUT what the golfer actually DOES in trying to benefit from "improvement 493" ACTUALLY helps or even fixes a problem that needs help and leads to unappreciated "improvement 276". It may not be the BEST way to get the real problem eliminated or reduced, but the technique used in delusional pursuit of "improvement 493" actually ends up making the putt "better." Remember, though, that "better" is not necessarily "a lot better" and is certainly not "the best".

For example, consider the "forward press" in putting. Usually taught as benefitting "true roll," the "forward press" is recommended to "deloft" the putter a bit at address. This delofting is rather stupid, though, because 1) why not just design the putter head with the desired loft?, and 2) "true roll" is an illusional goal since the grass changes the worst putt into the best putt is about the first 2-3 inches of grass-ball friction no matter hat stroke or putter design is THOUGHT to help the total putt for "better" "true roll".

BUT for many golfers -- probably in fact MOST golfers -- their hands and wrists at address have too little muscle tone and therefore shaping (not having been well taught or having a sound understanding of technique), and then in the stroke this too-little muscle tone allows the in-motion physics of putter and arms to change the hands and wrists from the address posture and shape and aim to "something else" in the midst of the back and thru stroking, with the result that online, solid strokes with good tempo and rhythm (and hence good line as aimed and good pace or touch as used to read the putt) gets confused and ill-performed and only done as required by the read by unknown manipulations that lead to streakiness and slumps. With this vast majority of golfers, a forward press can "tighten up" the shape of the lead hand by adding flex to the back of the lead wrist and extra muscle tone in the wrist and forearm. And the "idea" of stroking thru with the "forward press" maintained results in a more stable hand-and-wrist shape and form for the lead hand. That ALONE makes for a "better" stroke for these otherwise not-good, unorganized golfers -- a straighter, more solid, more rhythmical stroke for the intended line and pace to match the read and aim.

Nonetheless, as a TEACHER, I cannot leave matters there, since that validates stupid, accidental improvements to (somewhat) "better" but leaves unattained "a lot better" putting, and also does not engender a SKILLFUL golfer who actually comprehends and understands what technique is good and sound and why it causes good or bad performance. And without this correct knowledge, in fact, there is no going-forward correct diagnosis of causes of errors and therefore correct fixes to reduce or eliminate errors. If golfers are looking to the forward press for "better" "true roll", they are NOT looking to the hand shape firmness to control line and pace.

Just for clarity, what I teach about "forward press" is: you don't need it and instead should just "form up" the lead hand with sufficient muscle tone in the hand, wrist, and forearm to control the putter in motion for purposes of straight, online, solid, rhythmical strokes for line and distance as aimed for the read. Then the focus is upon the swinging of the arms straight thru impact with a square face and good rhythm. THAT leads to consistent, accurate putting with steady "feedback" about causes of poor line or pace control. But in the meantime, go ahead and experiment with a "forward press" to get "some improvement", and then chalk it up to the better shaping of the hand. Then "graduate" to shaping the hand without the "forward press". The "forward press" endangers the AIM of the putter face and confuses the accuracy of the exact moment the putter head transitions thru impact from swinging downward to the ball to swinging slightly upward thru impact. So I don't teach it -- not necessary for good strokes and unnecessarily complicating good strokes.

So, yes, but ...

Cheers!

[linked image]

Geoff Mangum
Putting Coach and Theorist

PuttingZone.com -- over 200 Certified PuttingZone Coaches teaching in 21 Countries Worldwide and growing strong!
The best putting instruction in the history of the game -- integrating the Four Skills of putting (reading, aiming, stroking for line, and stroking for delivery pace) by combining all putting lore in history with modern science for physics, anatomy, physiology, biomechanics, motor sports teaching and learning and performance, and especially the NEW brain science of the non-conscious processes of perception and movement action in putting skill.


    
This message has been edited by aceputt from IP address 71.95.221.26 on Jul 12, 2015 2:37 PM


 
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