In a conventional golf swing, the clubface opens and closes, rotating to the target line. But with the putter, this is often seen as undesirable. In this article I’ll examine how clubface rotation happens, whether it should, and if so, to what extent.

Pendulum-style

Many people discount that the putter can be swung like a pendulum because the club does not lie vertical at the start. But if you lean a grandfather clock back 20 degrees or so from vertical, does not the pendulum still swing? The requisite feature is not that the pendulum swings vertically, but that it swings in-plane along a theoretical flat surface.

Here are just a few examples to support why an in-plane swing is worth pursuing:

1. You can lay a STRAIGHT line on the flat surface of a plane, but not on a CURVED surface.
2. Inertial forces act to pull the clubhead in-line with the path of the hands, and thus to form a plane for the swing.
3. The best putters in the world swing the WHOLE putter in-plane, or very nearly so (regardless of what some may THINK that they do).

If a club is to swing within a single plane, it must begin the swing within that plane, the address plane, formed between the ball-to-target line and the club. The standard lie angle of a putter is typically 70 degrees, for which the address plane is inclined 20 degrees from vertical (90-20=70). The geometry of a swing within an inclined plane dictates that as the club rotates around the golfer, the clubhead travels up and away from the target line, toward the golfer’s side, on both sides of the lowest point of the arc. As this happens, the clubface will open and close to the target line, even when the clubface remains square to the flat surface of the plane. Additionally, the clubface may roll (rotating upon itself), opening and closing not only to the target line but also to the plane. Example: the Earth rotates around the Sun, and also rolls upon itself.

Modeling the swing

The putting model, “Iron Archie,” can swing a putter pendulum-style with clubface continually square to the in-plane arc when its “shoulders” are set to rotate parallel to the address plane. The only moving part of this simple machine is the entire shoulder/arm/club assembly around a central axis/hub.

Iron Archie in action

The human golfer CAN reproduce the single-action swing of Iron Archie simply by rotating the shoulders, or more accurately, the upper torso, parallel to the address plane.

A difference from the model

The most natural rotation of the shoulders is perpendicular to the spine, specifically a section of the thoracic spine just below the shoulders. This square rotation of shoulders-to-spine allows the whole spine, including the head, to remain fixed. This is why players who “rock the shoulders” on a steeper tilt may be observed with the head teetering back and forth. From an orthodox golf posture, the spine is not normally inclined to the degree that is perpendicular to the address plane. In this scenario (assumed throughout the article), if the golfer’s only movement were to rotate the shoulders naturally perpendicular to the spine, the club would move under and out of the address plane on both sides of the lowest point, the club carving a cone shape through space. In this scenario, a second movement must be added to keep the club moving in-plane – a vertical swinging of the arms from the shoulder joints — and this reality is no different with any other club. This specific action causes the golfer’s arm/club/clubface assembly to roll.

Learning from the best

A fine example of this “rolling” action is seen in the technique of arguably the greatest performer with the putter of our time, Tiger Woods. Tiger swings the putter near perfectly in-plane while maintaining a notably steady head position, indicating that his shoulders rotate mostly perpendicular to the central axis/hub. But since that area of his spine is more vertical than perpendicular to the swing plane, the clubface rolls, as the arms must swing from the shoulder joints to keep the club swinging in-plane. Tiger has been measured by the SAM PuttLab system to exhibit in the impact zone (4 inches before and after impact) 10.2 degrees of clubface rotation relative to the target line, of which 8.5 degrees is clubface roll, relative to the path of the clubhead. This degree of roll, in particular, is notably higher than other Tour players tested. To be clear, the roll of the clubface results not from the wrists rotating about themselves, independently of the upper arms (pronation and supination), but from the roll of the whole shoulder/arm/club assembly around a vertical axis within the swing plane. Thus, this higher degree of face rotation does not represent an undesirable manipulation of the hands, which some might see it as. In fact, the only way for Tiger to maintain a square face-to-plane relationship, all else the same, would be to roll the wrists independently of the upper arms — counter-clockwise in the backswing, then clockwise in the forward swing. Clearly, that would be the manipulation, an unnecessary added movement. And many have wandered down that dark road, often leading to a case of the dreaded “yips.”

Tiger Woods’ athletic posture with the thoracic spine (red line) inclined short of 90 degrees to the club, which incidentally lies at roughly 68 degrees to horizontal.

Tiger’s forearms roll over the swing plane. This is the action that rolls the clubface. In contrast, Iron Archie’s “forearms” remain parallel to the plane, allowing the clubface to remain perpendicular.

Seeing the light

The club, as it swings in-plane, will continually point to a straight line on the ground – a line within the plane – a “plane line.” Laser pointers can effectively be used to confirm an in-plane swing.

Practicing an in-plane swing. First, swinging the dominant arm with a laser pointer in-hand, then with the SmartStick training aid. The laser continually points straight to the white target line. Finally, flying solo.

A laser line-generator, like the LaserPutt training aid, can confirm an in-plane swing and also shed light on clubface roll. When the laser line remains on the target line:

1. The swing is in-plane to the target.
2. The clubface is maintaining a square relationship to that plane.

We saw both of those conditions achieved with Iron Archie in the first video in this article.

Comparing two in-plane swings with the LaserPutt. On the left is an Iron Archie-style “shoulder” swing; the right forearm remains in-plane while the clubface remains square to the plane. On the right is a Tiger Woods-style “arm” swing; the right forearm rotates out of plane slightly while the clubface rolls, evidenced by the laser line rotating off the target line. Even in this case, the LaserPutt provides valuable visual feedback as to whether you are returning the face squarely to impact. The PerfectStroke training aid serves as a suspended “plane line.”

The straight dope

Turning the spotlight to the so-called “straight-back-straight-through” style, in which the clubhead is supposedly to remain directly ABOVE the target line within a vertical plane, realize that when the club is inclined from vertical, this scenario would see the WHOLE club moving along a CURVED surface. I find the feel of this style notably less stable, less natural and less repeatable than the in-plane style. Still, it CAN be done, BUT if you’re hoping to power this style with a “shoulder” swing, know that your shoulders will need to rotate within a VERTICAL plane. This is unnatural at best, UNLESS you can incline your spine to parallel to the ground, but this is quite unnatural also.

Perhaps there was more method than madness to Michelle Wie’s adoption of this posture? Yet even she does not maintain the clubhead entirely within a vertical plane.

Proponents of the straight-back-straight-through style usually suggest also that the clubface should remain square to the target line. Again, to achieve this, either the shoulders must rotate within a vertical plane, or if not, then the golfer must actively roll the wrists about themselves to counter the roll resulting from the vertical arm swing required to maintain the clubhead within the vertical target plane. Frankly, either effort is an aberration. Further, I am not aware of a single player on any major professional tour who swings the putter head entirely within the vertical target plane. This style is mostly a myth. It makes some sense in theory, just not in practice.

Straight vs. curved

Have a look at the following two swings. Which looks straight and which looks curved/arced to you?

It’s a bit of a trick question, as both swings are in-plane. The swing on the right is viewed from within the vertical target plane, while the swing on the left is viewed from within the inclined address plane.

Swing like Archie or Tiger?

Both the style of Iron Archie and Tiger Woods produce the in-plane, pendulum-style swing. The main difference is in the relationship of the incline angles for the shoulder turn and the swing plane. The “flatter” or closer to horizontal the shoulder turn is from the swing plane, the more the clubface will roll, adding to the total face rotation. Many have concluded that less clubface rotation MUST automatically be “better,” less likely to be mis-timed, but consider these three points:

1. The additional clubface rotation results simply from the arms swinging the club in-plane while maintaining a fixed spine. The squaring of the face-to-plane for impact in the forward swing is achieved solely by reversing that single action, and not on timing any additional active action to that action.
2. A steady head position has always been deemed orthodox, especially when putting.
3. In the full swing, a so-called “square” position at the top of the back-swing is reached when the clubface rolls, building up to 90 degrees to the swing plane along the path of the clubhead.

Of course, the golfer may use a degree of shoulder tilt somewhere between parallel to the address plane and perpendicular to the spine. The arms are then required to swing from the shoulder sockets, more than Iron Archie (zero) but less than Tiger, producing less face rotation than Tiger but more than Iron Archie (zero). But since the degree to which the shoulders tilt affects the face-to-path alignment, as we have seen, variance in that angle during the swing can directly cause clubface misalignment at impact.

Anything Else?

For the in-plane, pendulum-style swing with the putter, since the clubhead path parallels the plane direction ONLY at the lowest point of the arc, in-line with the thoracic spine, this is where the back of the ball should be positioned. The elbow and wrist joints should be immobile also, maintaining the one-piece structure of a single pendulum, unlike the double-pendulum action used with other clubs.

Conclusion

Those interested in exploring the in-plane, pendulum-style swing with the putter will find the training aids highlighted in this article to provide essential feedback. When guided on an in-plane swing, golfers consistently discover a feeling that they intuitively sense to be most appropriate. Perhaps that’s because an in-plane swing is the accepted ideal with any other club — in the area approaching impact at the very least.

Your sense of touch may guide you, as the stable feel of the hands and clubhead swinging in-line with each other contrasts to the wobbly feel of motion out-of-plane. Your sense of direction may guide you also, since although the clubhead is constantly changing direction as it circles within the plane, the plane ITSELF has direction with the target.

Conflict arises from beliefs that make sense in theory but not in practice, such as the belief that the clubhead should move in-line with the target for an extended length rather than in-line with the hands. And although an in-plane swing FEELS right, it may not initially LOOK right to you. You must not be alarmed when you see the path of the clubhead progressing inside the target plane and the clubface opening to the target line as the clubhead swings up the straight, inclined address plane. As an old Jedi Master once said, “May the force be with you.”