- Putting Control
- Skid and Roll
- How STX Putters Minimize Skid Distance
- Dwell Time
- Compression Deflection
- Rebound Resilience
- Summary
Putting Control
Putting control has two components — direction and distance. Direction control (or angular dispersion), measures how far to the left or right the ball rolls from the centerline. Distance control is getting the ball to consistently travel the appropriate distance. It is helpful if the putter is "forgiving" of slight miss-hits so that for a given swing speed, the distance the ball travels doesn't vary much when the ball is struck slightly off-center.
Skid and Roll
When the putter strikes the ball, it propels the ball in the forward direction generally without much spin. It starts out flying a little bit above the ground as the loft on the putter gets the ball up out of the grass. When the ball "touches down", the bottom of the ball grabs the ground and slows down a bit. The top of the ball does not slow down, so the ball tumbles and starts to roll over. Because the ball is still moving forward faster than the speed that its roll rate would cause, the ball skids. Whenever the bottom of the ball touches the ground, friction causes the bottom to grab and slow down some more, further increasing the spin rate. During this period, the ball's forward momentum is traded for angular momentum (spin) until the ball has slowed down and spun up just enough to exactly balance the spin rate with the forward speed. The ball is now true-rolling. Once true-rolling, the ball's resistance to movement in the forward direction is a small fraction of its sideways-sliding resistance, so it tends to continue rolling in a straight line. Like a gyroscope, the ball inherently resists changes to the axis of spin.
Just like a skidding car, a skidding ball is out of control, both in direction and speed. During the skid phase, the ball is at the mercy of every imperfection in the green's surface, with each little bump that it hits changing the ball's direction and speed. By the time the ball begins it's true-roll, it may be traveling on the wrong line. Therefore, it is advantageous to minimize the distance that the ball skids before it starts its true roll.
How STX Putters Minimize Skid Distance
Tests using high-speed cameras show that STX putters make golf balls skid less and roll sooner than do other putters. On one such test, the STX soft insert putter skid distance was 40% less than two major competitors.
The key to reducing skid is to give the ball as much topspin as possible before it leaves the putter face. Although a golfer could top the ball, that would be hard to control. STX's face inserts take a big step in the right direction with their long dwell time and high coefficient of friction.
Dwell Time
Dwell time refers to the amount of time the ball remains in contact with the putter face. The longer the dwell time, the more opportunity the putter has to "hold" the ball for the purpose of imparting topspin. In addition, a longer dwell time improves the feel of the putter. Testing shows STX putters have almost twice the dwell time of putters with harder inserts and nearly three times the dwell time of metal faced putters. The difference is due to the relatively high coefficient of friction of STX's inserts.
Compression Deflection
When a putter strikes a golf ball, the ball compresses (becomes shorter from front to back and wider in the girth) for an instant, and then rebounds to its initial shape, causing the ball to spring forward from the club face. A perfect golf ball would rebound in a direction determined only by the direction the putter is traveling and the angle of the putter face relative to that direction. However, real golf balls are not perfectly uniform. Imperfections in the ball can cause the rebound direction to differ slightly. This deviation is called compression deflection. Reducing the amount that the ball is compressed reduces the compression deflection. When the STX face insert makes contact with the ball, the insert compresses resulting in less ball compression deflection and a truer roll.
Rebound Resilience
Resilience refers to the ability of a material to recover its initial shape after being deformed. The resilience of a golf ball permits it to spring away from a clubface after being compressed by the impact. The effective resilience for a putter striking a ball is a combination of the resilience of the ball and the putter face. To maximize control, it is better for a substantial portion of the effective resilience to come from the putter face, not from compression of the ball, to reduce compression deflection. It is also desirable for the overall effective resilience to be relatively high, thus avoiding loss of energy at impact. Lower overall resilience requires you to swing the putter harder to propel the ball a given distance, typically decreasing your accuracy on long putts. STX inserts have a high intrinsic resilience, resulting in a high rebound resilience compared to other putters. A putter with a soft face insert material with a high rebound resilience gives you more control both in distance and direction.
Summary
STX putters increase putting accuracy because of:- Short skid distance due to high dwell time and high coefficient of friction
- Low compression deflection
- High rebound resilience