Golf Club Definitions

Engine of the Golf Club: The engine of the golf club is the golfer. The golfer is the entity that provides the power and creates the motion. The golfer is the engine… end of story.

The Grip of the Golf Club: The grip is what connects the golfer to the club. The grip must provide a comfortable, snug, and secure connection to the golf club. It must fit in such a way that it helps the golfer impart as much energy as possible into the rest of the club without distraction or interference. And of course, as many women golfers have informed me, the color must match their favorite decor! Yes ma’am I will do my best to make it so!

The Transmission of the Golf Club: The transmission of the golf club is the shaft. The shaft determines the length, overall flexibility, and bend profile of the club. A properly fit shaft is geared to the golfers swing, just as a transmission is properly geared to the engine of a car. A shaft that properly fits the golfer allows the golfer to impart the maximum amount of energy into the club possible, with the proper trajectory, to produce the farthest distance, while achieving the best accuracy. Anything less is a waste of energy, time, money, and strokes.

The Head of the Golf Club: The head of the golf club is like a tire on a car. It is where the rubber meets the road, or in this case where the steel meets the iothane or urethane cover, but the principal is the same. It is the main interface with the golf ball, and must achieve the best friction transfer possible with the ball, to produce the best energy transfer, to properly compress the ball, to create the best ball speed, with the proper launch angle, with the proper ball spin, to achieve the best distance and accuracy. And please note, that the grooves in a golf clubhead (NO MATTER THE SHAPE), do not necessarily create spin. Spin is determined by loft, angle of attack, and friction between the clubface and the ball. The grooves in a golf club perform the same function as the tread in the tires of a car (one reason I used a tire as a comparison). They channel away water and debris from the face (just like the tread in a tire does on the road), to allow the rest of the clubface to have as much friction with the ball possible. In fact (and it has been measured and proven), that in the case of a dry environment, with little to no debris (like a hitting mat or even a dry fairway), a clubhead with no grooves at all will generate more spin than one with grooves. If you don’t believe this, then ask a drag race car driver why their rear tires have no tread, and they will tell you the same thing… better friction on dry pavement. Interestingly enough, a wedge with U-grooves is now illegal on tour, but a wedge with no grooves is not.

Shaft Spine: The golf shaft spine (mainly applicable to steel shafts), is the seam or weld of a steel shaft, which is typically aligned with the target line of the club when assembled (perpendicular with the face of the club). A steel shaft begins as a flat sheet of metal and is formed into a tube, either graduated or in steps. The seam or weld where the resulting tube is joined together is referred to as the spine of the shaft. As the steel shaft flexes (bends) the spine wants to literally pop or twist itself toward the leading edge of the bend, sometimes violently. Graphite shafts however are typically wound around a mandrill, in different layers, with different shapes strategically placed along the shaft. This is how the manufacturer produces the graphite shaft’s desired bend profile. Therefore they typically do not have a defined spine like a steel shaft will, but graphite shafts do need to be pured for consistent performance (see Pureing below). While it is true that the bend or flexing of a shaft is actually turning during the swing, the unload point (the point where the shaft bends forward just before impact), should have the spine and clubface aligned with the target line. The theory is that if the spine is properly aligned with the target line of the clubface, there will be minimal twisting effect of the head at the unload point (and at impact), resulting in a more consistent and accurate performance of the club. Please note however, that even after finding the spine of a steel shaft it should also be pured just like a graphite shaft. Most of the time the pure point of a steel shaft is located 90 degrees from the spine, but there are cases where this does not always hold true. Sometimes the spine of a steel shaft is not straight, and there can even be multiple spines in different segments along the shaft, therefore pureing of the shaft is necessary to ensure the club is assembled in the most consistent plane.

Shaft Pureing: This is the process of finding the most consistent oscillation point (or oscillation plane) of a shaft. The butt end of an uncut shaft is clamped (typically in a frequency meter clamp), a weight of like mass to the head used in the final club is connected to the tip, and the tip of the shaft with the weight is then oscillated in a known plane. The desired effect is to have the tip stay perfectly in the same plane as it oscillates. If the tip does not stay in plane (i.e. does figure 8s as it oscillates), then the shaft is unclamped, turned a few degrees, clamped, and oscillated again. Once the proper plane of the shaft is found the 12 o’clock position is marked, and the shaft is assembled into the clubhead with the mark in the 12 o’clock position of the club (on top and parallel with the clubface). The theory here (as it is with spinning), is to achieve the most consistent and stable unload point of the club (the point where the shaft bends forward just before impact). The reason the pure point of the shaft is placed in the 12 o’clock position (parallel with the club face instead of perpendicular as with a spine), is to keep the head in the most stable plane at the unload point, thus having a more consistent and accurate performance of the club.

Shaft Flex (Flexibility): Unfortunately the shaft industry has established absolutely NO standard for flex definition. Yes we see letters on the shafts that are supposed to indicate shaft flexibility, such as:

X (Extra Stiff) (Stiffer)

S (Stiff)

R (Regular)

A (Amateur, aka Senior)

L (Ladies) (More Flexible)

In reality these indicators mean absolutely nothing, with the exception as to how they relate to the other letters of the same model shaft. For example Shaft Model A has a nice graduation of stiffness across the letters, and so does Shaft Model B, but Model A’s R-Flex is actually stiffer than Model B’s X-Flex. In fact I can show you an L-Flex shaft that is stiffer than another manufacture’s S-Flex shaft. For all practical purposes currently the only reliable way shaft flexibility is determined is by measuring a shaft’s frequency. A shaft is clamped in a fixture, a known weight is attached to the tip, and the tip is gently bumped and oscillated through or over a frequency counter device. The frequency is measured in Cycles Per Minute (aka CPM). A shaft’s butt frequency is derived by clamping the last 5 inches of the butt end of an uncut shaft, attaching a tip weight to the tip end (~200 grams for a wood shaft, and ~250 grams for an iron shaft), then oscillating the tip over a frequency counter. A higher frequency count equates to a stiffer shaft, and a lower frequency count equates to a more flexible shaft. The shaft frequency can be adjusted higher by tip trimming, and overall length.

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