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"I am confident that your professional approach to both clubfitting and clubmaking would benefit any golfer regardless of their skill level."
-- Patrick Therrien

"I hit just about every shot straight and solid"
-- Michael Larkin

Variable Face Thickness

Much fuss has been made in the past year or two about the effect of Moment of Inertia on driver performance. In truth, the development of variable thickness face designs is probably just as important, if not moreso. Yet, fewer people pay any attention to it. The cynic in me thinks this is because the USGA has yet to come up with a rule restricting it, thus making everyone believe that getting a club at the "USGA maximum" for Variable Face Thickness design is equivalent to buying a magic wand. As a result, the major companies' marketing departments have not yet built as many marketing campaigns around the concept.

This does not make the design technique irrelevant, though. On the contrary, if you combine a good variable face thickness design with a high Moment of Inertia, you should end up with a driver that is noticeably more consistent for distance on off-centre hits, provided the driver isn't ruined by a poor build for length, loft, shaft weight, flex and bend pattern, club balance, etc.

How does Variable Face Thickness work? Here is an analogy that makes things clear: Imagine someone jumping on a trampoline. When that person jumps in the middle, the trampoline bends down a certain amount, and the person bounces up a certain amount. When the person jumps to the side, both are reduced. Then stiffen up the trampoline mat so that it doesn�t stretch and bend as much...now, there is much less difference between the person jumping in the middle, and the person jumping at the sides. Finally, loosen the springs so the person in the middle has just as much bounce as he/she did before the middle of the mast was stiffened.

That is pretty much what you have with variable face drivers. No, technically, the face doesn�t "spring" the ball off the face. It does "deflect" a bit, however, resulting in the ball compressing less, and absorbing energy from impact more. It comes off the face with less loss of energy from impact, and so flies farther. In other words, the club has a higher Coefficient of Restitution, or COR, as it is called in golf. You may remember the USGA limited that a few years ago, and now all good-quality drivers are made to that limit. If you miss the centre of the face, however, the COR goes down. It can't help it. The face is like a drum, it deflects more in the middle than at the sides. That can't be changed. What Variable Face Thickness does is reduce the amount the COR goes down on miss hits. On the best of them, the difference on 3/4" to 1" miss hits can actually be measured in yards. Not a lot of yards, true, but add that to high MOI, correct loft, and all the build factors of length, weight, balance, etc...and a person switching from a relatively poor fit to a very good one can start to see substantial improvements of 10 yards or more - sometimes a lot more!

This design element isn't just limited to drivers. There are irons out there as well with Variable Face Thickness. If they are combined with a deep cavity or a good perimiter-weighted hollow design, these are going to be the most forgiving, consistent irons you can get your hands on. They will also be more expensive, because manufacturing them is more involved. There are even some designs that combine variable thickness faces with ultra-thin, high-COR designs to improve ballspeed off the face. Some have been shown to add an extra half-club or more of distance to shots, assuming the player in question actually swings the club fast enough to deflect the face at impact.

One final note: There are advertisements out there stating that such and such a clubface is "designed for maximum ballspeed from everywhere on the face", or similar wording. Do not be fooled into thinking this means the entire face provides the same USGA maximum face deflection. As explained above, this would be impossible. To do so would require a very rigid face that didn�t bend anywhere, and a very flexible border that deflected a very great deal. This is impossible in a golf clubhead. Metal is not naturally rigid like stone or concrete. It does bend and flex. A perfectly rigid metal face would have to be very thick and heavy. This would a) make the head much too heavy to build a swingable club, and b) probably have frequent cracking or weld failure problems along the ultra-thin, flexible border.

All that these advertisements mean is that the club in question has a Variable Face Thickness design. That's it. They have made all points of the face deflect as much as they know how to make those points deflect, but they don't all deflect equally. The best way to maximize distance with your driver - or any club - is still to get as many centre face or very close to centre face impacts as possible. The best way to do that - in fact, the only way - is to get properly fitted for all of the twenty-five variables that go into a golf club set.

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Based in Richmond Hill, Ontario, Sean Baines is a PCS-certified "Class A" clubmaker and the owner of Clubs That Fit. He is committed to providing quality, game-enhancing clubs and highly personalized service to golfers of all ages and skill levels.