This feels like a stupid question, I apologize if it is. (With luck, it may verbalize a common misconception that high scorers have).

Imagine that I drew a cross-hair on the face of a putter (one line horizontal side to side, one line vertical top to bottom). The intersection of the two lines represents the impact point of the putter face and the ball.

Where is that intersection point on the face of the putter, especially in the vertical (top to bottom) direction?

I ask this question because I recently broke through a mis-perception I had, and, I might as well try to put my mental image back together the "right" way.

I tried Fred Shoemaker's "putt with the leading edge of a wedge" exercise. After succeeding at it, I sat down and actually looked at my putter and a ball.

To my surprise, I found that the putter face is only half as high as the ball. This appears to be the case with most putters.

This leads me to conclude that when making a stroke, if one were to glide the putter "just above" the green, the impact point would be right near the top edge of the putter. In fact, it would miss above the putter face insert, if the putter had an insert.

I used to think that the impact point should be the center of the putter face (in, both, the vertical and horizontal directions). I, also, used to think that the putter face was about as tall as a ball (until I paid attention to this detail).

To accomplish impact at vertical center with a putter that is only half as high as a ball, one would need to hold the putter about one-quarter of the putter-face height above the green.

Indeed, when I consciously do so (hover the putter about 1/2 inch above the ground), I appear to obtain a "better" roll of the ball. It feels more solid, the ball doesn't hop - but, I don't know if it is more or less repeatable.

Geoff's book "Optimal Putting" appears to say that the putter should just graze the grass (page 128). Likewise, Utley's book (the coloured picture section) shows that about 1/2 of the ball is visible above the putter at impact.

Now I'm confused. Does the ball sit deeper in the grass of the green than I think? Does the loft of the putter face lower the impact point, hence, requiring one to just brush the grass for a proper strike? Are putters designed for impact near the top edge? Or, do people who putt well make contact at the center of the face by unconsciously lifting / hovering the putter on the downswing?

pt

Dear Paul,

Great question! According to Norman Lindsay, the "correct" point vertically on the putter face is not how far up from the bottom of the putter face the point should be (e.g., halfway up from the bottom edge), but instead needs to be thought of in terms of whether the impact point is "above or below the putter head's center of gravity" So where is the putter head COG? That depends upon the designer's choice.

For Lindsay and most putters, the putter head COG is LOWER than the center of the putter face in the vertical dimension. So the preferred relationship is "impact point on putter face ABOVE putter head COG". According to Lindsay, this results in a "vertical gearing effect" of the putter face over the top quadrant of the ball.

Other designers place the putter head COG high, in the idea that a high COG in the putter head impacts the top quadrant in the correct way and promotes quicker forward top-over-bottom rolling (e.g., Aserta "Inverted Mass" technology).

The other factor involved here is a combination of dynamic loft from loft at address and loft at bottom of stroke and loft at the start and end of impact on the ball -- this determines really where on the face the impact will occur in the absence of "lifting" or otherwise manipulating the stroke out of the plain-jane pendular arcing up and down and up again in the back and thru swinging. Usually, a 3-degree lofted putter without oddities in address or stroke (e.g., forward press at address, hands ahead keeping putter head artificially low and level thru impact, etc.) returns the putter face to the bottom of the stroke with the same 3 degrees of loft and then adds more loft dynamically between there and wherever the ball position is in relation to the bottom of the stroke. So impact often starts around 3.5 to 5 degrees of dynamic loft and ends shortly thereafter with a wee bit more dynamic loft when ball separates off putter face. (Inserts and face material and treatment affect how long the contact persists and thus how much the dynamic loft changes during contact.)

The third factor comes from the fact that the ONLY spoit on the back of the ball that a putter face can possibly impact is the spot where the dynamic loft of the putter matches the orientation of the tangent plane on the back of the ball. The tangent plane is the orientation of a flat poker chip or credit card when placed flush to the surface of a ball. At the point on the bottom (or top) of the ball, the tangent plane is horizontal and matches the plane of the equator of the ball (as if the top half of the ball is sliced off at the equator and a round table is exposed inside the ball). When the tangent plane is on the spot on the equator of the ball, the tangent plane is vertical to the equator. When the tangent plane is at a spot on the lower back of the ball, the tangent plane leans in a positive direction (top edge farther from target than bottom edge), and a tangent plane on the top quadrant leans in a negative direction (top edge closer to target than bottom edge). Whatever the tangent plane at a spot on the back of the ball, the ONLY dynamic loft that can touch that spot has to be the SAME angle of lean in relation to the equator. Only a zero-loft putter face at impact can touch the back of the ball on the equator. Only a positive 3-degree loft at impact can touch the spot on the back of the ball whose tangent plane leans 3 degrees top-back from the vertical tangent plane at the equator, in the lower quadrant of the back of the ball at a spot identified by a line out of the ball center angled down from the equatorial plane by 3 degrees. And so forth.

The final factor is how the golfer's stroke motion affects the vertical orientation of the putter face in relation to how the ball sits on the green. ordinarily, putter faces have a vertical height of about 1 inch, and the ball is 1.68 inches in diameter, and the "equator" of the ball is 0.84 inches off the ground. So a putter that sits on the same dirt that the ball sits on that also impacts the back of the ball right at the bottom of the stroke (i.e., no extra loft added due to ball position forward of the bottom) results in the impact point on the putter face being 0.84 inches up from the dirt (and the bottom edge of the putter face), which happens to be "above" the center of the putter face at 0.5 inches from the bottom edge. In the more usual case of ball position being somewhat ahead of the bottom of the stroke, there is loft getting added as the bottom of the putter arcs upward in the forward swing past impact. How much up it arcs before contact with the ball depends on how high up the pivot of the stroke is. A short person has a more sharply radiused and uprising stroke than does a taller person. So taller people have less dynamic loft and less change in loft from start of impact to end of ball-putter contact.

Most golfers lift the putter head thru impact with the forearm muscles getting active. How much? About 1/16th of an inch to 1/8th of an inch, usually. If the golfer starts the stroke by first "hovering" the putter on the top of the grass, that elevates the putter sole by about 1/8th of an inch, usually, as this is standard "mow heights" for normal greenkeeping. So that is a total of about 1/4th of an inch or less. Here is a typical representation of a putter at impact with the bottom of the putter about 1/4th inch above the dirt thru impact.



Then if the golfer plays the ball an inch or two ahead of the bottom of the stroke and bottoms the stroke out at the bottom without oddities in the stroke motion, the sole rises into impact over 2 inches for a 6-foot tall golfer with a pivot 54 inches above the ground about 0.075 inches (hardly any -- a little more than 1/16th an inch (0.0625 inches). This ball position adds about 1.12 degrees to the beginning (static) loft of 3 degrees, so the tangent plane of contact is the spot on the ball 4.12 degrees leaning off vertical, or a spot aimed at by a line from the center of the ball to the back of the ball that is angled down off the equator plane by 4.12 degrees. This is the only spot on the ball where where contact can start.

Here's a picture of a ball-putter impact with the ball played 2 inches ahead of the bottom of a 3-degree lofted putter as swung by a 6-foot tall golfer with his pivot 54 inches above the ground, without hovering of lifting:



So where is this point of contact on the putter face vertically? The hovering and lifting elevates the putter face and hence lowers the point of contact of the ball on the face by 1/4th an inch (0.25 inch) and the dynamic rising of the putter past the bottom to the back of the ball 2 inches ahead or forward of the bottom of the stroke adds another 0.075 inch, so that lowers the spot on the putter face a total of 0.325 inches BELOW the center of the putter face vertically (about 1/3rd of an inch). If the "usual" point of contact is 0.84 inch above the bottom of the putter face (i.e., contact right on the ball's equator without lifting, hovering, or playing the ball ahead of the bottom), then this hovering, lifting, and ball position LOWERS this 0.84 inch spot by 0.325 inch, so a resulting impact spot on the face that is 0.515 inch above the bottom of the face. NORMALLY HITS THE BALL IN THE MIDDLE OF THE FACE VERTICALLY or very closely so, and "no lifting or hovering" hits the ball with a spot on the putter face higher than that by about 1/4th inch, halfway between the vertical middle and the top edge of the face. While contact lasts (0.005 to 0.010 seconds), depending upon face material and velocity of impact and hardness of ball, a little extra loft is added AND the ball slides down the face a bit closer to the middle of the face.

Let me know if this answers your issue.

Cheers!

Geoff Mangum
Putting Coach and Theorist

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Geoff, thank you. Yes, that does answer my main question, i.e. that the ball contacts the face roughly at the vertical center regardless of hovering or no hovering (I probably have an exaggerated sense of how high I actually hover the putter prior to the stroke - I'll ask a colleague to observe) and that nothing nutty, like impact with the top edge of the putter, actually happens in a good stroke.

Visiting Lindsay's site did leave me scratching my head with secondary, less important (I think), questions, e.g. what does he mean by "vertical gearing", etc? As I see it, COG, in a rigid thing like a putter, acts as a center of rotation. Impacting above the cog would cause some (slight?) progressive backward tilting of the putter face during the time of impact and v.v. for impact below the cog. This would cause the impact point to move vertically towards the cog during the "dwell" time. In an above the cog impact, this means that the impact point moves down the face, imparting upward roll on the ball (i.e. topspin). Is that the gearing effect? Hmmm. Obviously I need to ponder this some more to grok it fully. (And a business question ;- if he holds a patent for grooved putter faces, is Rife, et al, paying him a license fee?).

pt

Hi Geoff ... and yes I've done the geometric trigonometry between the ball and putter face over an ~54 inch stroking radius as well as an ~32 inch wrist pivot stroking radius ... and I've come to the intuitive conclusion that it's all a crock..!!!

The impact spot, the so-called face loft, the stroking path, the face angle, rate of change of momentum (de/acceleration) and of course the position of the putter head CoG ... they all become irrelevant because they are all within the margin of error inherent in the putting stroke itself.

My torqued putting stroke is secure and consistent, and I have experimented with many putter designs. Conclusion? If you can't putt effectively with a Wilson 8802-style heel-shafted putter you are a klutz.

When somebody says they are having problems rotating their bodies a few degrees (~one degree for every inch of backstroke) and controlling their hands moving half the distance the putter head moves ... well that only exposes their dearth of practice. When somebody imagines that their putter face must be machined to within 10 thou flatness, you know you are dealing with a deluding mind.

I'm sorry, Geoff ... but squeezing the last hundredth or thousandth of an inch measurement when analysing the putting stroke impact, that's just irrelevant. Then there is the inconsistency of the dimpled ball surface that defeats any minute analysis of putting geometry.

Putting for most is a lottery, and there is no use for them to think they can better the odds by arming themselves with the putter that won on the weekend, or the one that 'feeels' good. Practice is necessary to not only establish some level of consistency, but it also provides an understanding of one's physical irregularities.

Dear sammy,

You and I agree whole heartedly about the larger-picture margins of error in typical putting. Golfers' problems aiming putters accurately swamp out of significance any assistance they get from almost all alignment marks designed into a putter by some guy working for a club company who used to polish putters to make them pretty. The same is true of golfers' margin of error in reading putts accurately and marrying the aim and touch to their reads -- not very good at all -- so what difference to scoring does a year's worth of work on the PuttLab polishing stroke mechanics parameters have to do with the price of tea in China? Mostly "butkiss", in the larger scheme of playing the game. The same is definitely true of touch -- no touch, stroke mechanics hardly matter, as almost all putts have break and whether the golfer adheres to the break even if he can perceive the break is simply and completely about touch.

Hard cheese for stroke technology gurus, but there it is.

The nice book by Frank D. Werner & Richard C. Grieg, How Golf Clubs Really Work and How to Optimize Their Design (Jackson, WY: Origins, 2000), used the common sense criterion "does the putter design feature help the golfer take fewer strokes". They concluded that EVERY design feature technically helped a little, but the size of the effect was grossly swamped out of real significance by the magnitude of golfers' difficulties reading putts, aiming the putter and stroke, making a stroke that goes where aimed, and controlling the distance and pace of the putt.

If you want to know whether your work on touch is causing problems with square impact, you don't want to use a PuttLab for that. My pal Jerry Moser makes a nice laser gizmo (the Laz Aligner) that reads out whether the putter face transits the impact zone squarely or not for about $75.


Open Stroke thru Impact


Closed Stroke thru Impact


Square Stroke thru Impact

If you want to take "data" about your path, just place a second and third ball down to the inside of the heel's line of motion back and thru and see whether you hit these balls making a stroke, or stick tee pegs down where you think the stroke should go.

If you want to "control" path or rotation or acceleration, what sort would you like to have and why? Your choice better be connected to reading, aiming, and touch, or else you are chasing a Chimera in the data precision.

Cheers!

Geoff Mangum
Putting Coach and Theorist

Geoff Mangum's
PuttingZone
PuttingZone Clinics
Flatstick Forum
PuttingZone Channel on YouTube
PuttingZone Picasweb Image Gallery

Golf's most advanced and comprehensive putting instruction -- you're either in the PuttingZone, or not.

Over 2.5 million visits -- 200,000 monthly from 50+ countries -- and growing strong.