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1.  Introduction 2.  Summary of Innovations 3. Loft and Lie Angles 4. Face Angle 5. Bounce 6. Club Head Center of Mass (cm) or (cg) 7. Facts About Impact 8. Relative Shaft Flex 9. Lie Angle 10. Horizontal Face Bulge & Gear effect 11. Cavity Back Irons 12. Torque (Shaft Twist) and Shaft Dynamics 13. Swing Paths & Head Orientations at Impact 14. Swing Weight 15. Offset Heads 16. Head Materials - Properties - Uses

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-In short, you should find that the newer designs are much more forgiving, easier to use, and do hit the ball farther as well.

 

- Inserts of heavier materials can now be more readily attached at key spots on the head to change club characteristics , i.e., locating it at the rear of the sole to further heighten ball flight and lengthen ball carry.(see the Golf Tryst woods of the Product Catalog as an example).

 

 

 

- Deeper faces - higher from the sole to the top the head - can be more easily employed, often yielding a more penetrating ball flight. (provided of course the player remembers to tee up the ball high enough).

 

- Springier faces, with a trampoline effect, can now be made. This is a controversial subject, with some designs ruled non-conforming by the USGA. There is a body of thought which argues against the design, saying that if you fail to hit the ball in the center of the face, you will direct the ball to the left or right depending on point of contact. Others argue that the spring action has to fit your swing too perfectly - otherwise the ball leaves the face either too early or too late and energy transfer is actually reduced. And yet, there are many examples of players who have found these clubs to be beneficial, who claim they have "hot" faces that propel the ball farther. The jury is still out on this subject, generally speaking, but we do know that there are players who are benefitting from these heads.

 

C- Graphite Shafts have had as much impact, especially for woods, if not more, as any other advance to date. These carbon fiber composites are made out of thin strings of fiber that are rolled into sheets. The sheets are then cut into patterns (a little like a tailor cutting patterns for parts of a garment), wrapped onto a mandrell and carefully wound about until there are sufficient wraps for the given design. The whole thing is baked, then sanded, painted and inspected. Techniques have improved greatly in the last 10 years and these are not the fragile pieces often seen in the past. The strings come in 3 general categories;- standard modulus; high modulus; and ultra high modulus. Each have somewhat different properties, but standard is a touch heavier than high, which is a touch heavier than ultra high. None are better than the other in an absolute sense. You employ them, sometimes in combination, depending on what you are trying to do, what sort of a club you are trying to make.

 

All of them are very much lighter than steel, in many cases more than 60 grams ( 2oz.) lighter. They can be made either stiffer or more flexible than steel shafts, but it is difficult to design the low torque values inherent in steel shafts without a loss in tip action. Tour pro's tend to use steel shafts in their irons for better control, where accuracy and not distance is their goal. However, more and more players overall have tended to use graphite shafts for just about everything with good satisfaction. The gains in ease of use has not been confined to seniors and ladies, but has been a big plus all across the spectrum of players. The features that come from using graphite shafts are commonly:-

 

 

 

 

 

 

  - Lighter clubs overall with heavier heads, i.e. a 43" driver that may have had a 200 gram head with a steel shaft before can now be made with a head up to 212 grams with no increase in strain while swinging. More effective mass at impact means more distance.

 

- Clubs can be made longer than before, up to 50" in some drivers. The added length generally yields a gain of about 7 yards per each extra inch due to the longer arc and the higher impact velocity that the golfer can achieve. While it is true that most players have trouble with lengths beyond 45", (squaring up the face is difficult and they lose some accuracy as well), there are nontheless a certain few who handle very long clubs well.

 

- The slicers have a better chance of straightening out their shots, of making a better pass at the ball, with this higher ease of use.

 

- Designers can use lower lofts , say 10 degrees instead of 11 degrees on a driver, since the greater tip action found in a well designed shaft will produce a higher ball flight than before. At collision, the lower loft on a well struck shot produces better energy transfer to the ball. For long hitters this tends to get the spin of the ball, the rpm's in flight, down to more optimum levels.

 

- Flex points can be easily placed in the shafts at key locations for assorted players, i.e., low for the slower swings, towards the middle for the higher speeds, and higher yet for + 105 mph swingers. This tends to restore, to orient, the head to its natural loft at impact which the player started with at address.

 

- More than one flex point can now be designed into a shaft so that the lower one can provide a little extra acceleration to the club head just before impact. This is difficult to do, but now possible.

 

- Clubs much easier to accelerate, much easier to control.

 

D- Golf balls have improved so greatly in recent years that many feel that this is as big a breakthrough area as anything else that has transpired. They do not seem to cut or nick the way they once did, they go farther and straighter, and they do not go ovate or out of round as was common before. If you can, you should have your PGA pro recommend what fits your swing and your equipment. You may have to do some experimenting to match a ball to your club heads so the ball compresses optimally and springs off the face at your desired launch angle. The many choices are so numerous that we cannot list them here. In general, you will find:-

 

- Different compressions, such as 100, 90, ladies (or 80), as well as no compression given but rather a some generic description that describes the type of player who should use the particular model. In general, the long hitters would choose the 100 while 90 would serve most men and 80 would serve most women.

- Different spin rates to fit the player who wants more or less spin.

- Different materials in the cover, i.e., surlyn, balata, etc.

- Different construction, such as, 2- piece, 3-piece, wound, etc.

- Different dimple patterns for flight through the air.

 

Note:- If you are shopping for balls, do not bounce several balls off the floor thinking that the one that bounces highest is the liveliest. You cannot compress it enough to find out anything meaningful. Indeed, a ball that is less lively could bounce higher.  

 

 

The center of mass will influence the flight of the ball, depending on where it is located in the club head.

 

- If it is towards the rear it will propel the ball at a higher launch angle. This is because the club head and shaft are not absolutely rigid. Upon impact, the club head loses some velocity. Since the cm of the head is so far back the head curls upwards, rotating around the cm during the collision, imparting a higher launch angle.

 

-If the cm is in the middle, from front to back, then the launch angle will be near the same as the head's rated loft.

 

- If the cm is in a forward location the head will do so little rotating that the launch angle will be somewhat low.

 

All of this is expected when the player makes a reasonably square hit.

 

 

 

 

 

 

Likewise, the position of the cm in the vertical direction- high, middle or low- will also determine launch angle.

 

- If it is low you will have a high launch angle.

 

- If it in the middle you wiil have an angle close to the head's rated loft.

 

- If the cm is high you will have a low ball flight.

 

 

Of course, as you contemplate a wood purchase, you will have no way of knowing where the cm of the head actually is. You should first determine the type of ball flight you want - high, middle, or low. (You already know what your difficulties are, if any).

 

- In the case of a wood made of stainless steel, it will tend to have its cm slightly forward, and the ball filght will be close to the rated loft. If you have trouble getting the ball airborne, for example, choose a loft that is around 11 degrees or even higher. 

 

-In our experience, many people play fairway woods with too little loft. These clubs are there to advance the ball with accuracy, and land on a green without too much roll. Unless you have a problem of very high shots, you should try to find more forgiving lofts, like 15 or 16 degrees on a #3 wood and 20 or 21 degrees on a #5 wood.

 

- As for titanium drivers, they tend to have their cm  back in the head, yielding higher ball flight. Here a 10 degree driver will produce the equivalent ball flight as a 10.5 degree to 11 degree stainless steel driver. You will have to check  the description of the driver carefully to see what the manufacturer has to say about the head in question.

 

 

The time of contact between ball and driver club face is astonishingly short- between 4/10,000 and 5/10,000 of a second. We have a very hard striker hitting a very hard ball so this is not completely surprising. And the force from such a short impact is huge- well over a ton at 100mph swing speed. Most of the mass in the momentum equations (MV) is found in the club itself, with a small amount coming from the shaft and the player's arms. Estimates show that most men contribute around 80 grams more of effective mass than women, on average. This is not much and explains why there are many smaller people, men and women, who can propel the ball a long way. Most of the mass is given to you by the manufacturer, so there is not a lot you can add in the way of muscle. The time is too short. It becomes clear, therefore, that the keys to distance are:-

 

- Technique- the ability to swing properly and make good contact- the ability to accelerate to higher swing speeds.

- Shaft- you want that to fit, store energy and release it just at impact.

- Since there are always losses in collisions due to the heat and distortions of the impact, you want heads that minimize those losses. 

 

 

The drawing below was made from collision tests putting a load cell on the hosel of a driver and hooking it up to an oscilloscope. We used a tour player from the LPGA who brought her club up to 101 mph at impact. (this drawing is from one of our patents). The build up of force from the short impulse should be obvious.

 

 

 

 

The standard way of measuring the shaft flex is to affix it to a deflection board. The butt end is securely fastened and the head end is suspended freely. A 6 lb. weight is then hung from the head, at the hosel, and the whole club will droop, with the tip deflecting the most. You then measure in inches how far the tip is from the horizontal line where you started and this figure tells you your relative stiffness. The longer you make a club in any given shaft rating, S, R or what have you, the more the club will deflect at the tip. The reverse is true if you make the club shorter, of course.

 

The industry does not have any agreed upon standard, for any of the lengths, but when you examine the shafts of the many manufacturers you find their actual shaft deflections are not too dissimilar. Here we tend to think of a 44" driver that deflects less than 5 inches as X-stiff; between 5 and 6 inches as Stiff; and between 6 and 7 inches as Regular.

 

There is another method of measuring relative stiffness and that is by loading the club into a frequency machine. When you pull down the head a bit and then release it, you cause it to vibrate. The vibration cycles are measured in cycles per second, cps, or cycles per minute, cpm, depending on what machine you care to use. The higher the number, the stiffer the shaft. The lower the number the more flexible the shaft. The shorter the club, the higher the number and vice versa for the longer the club. This is a very useful tool for custom fitting but the deflection board seems to have much greater use due to its simplicity.

 

 

This is the angle formed when the club sole is perfectly flat on the ground. It is deliberately put in at an angle that is set by the manufacturer. If the angle does not fit you there can be problems. This is of concern mainly with irons, where you want to take a divot by slicing through the earth. At impact, if the angle is too upright the heel will dig into the ground and the head will rotate, pulling the ball to the left. On too flat a lie the reverse will happen and the ball will fly to the right.

 

Players often adjust without even thinking about it. When the club is too flat they lean towards the ball and pull their hands in and down, trying to bring the toe up and the heel down. And the reverse happens when the lie is too upright. This can throw the swing out of kilter after a while. If your address posture is poor, then you may be causing the problem rather than the club.

 

As you swing the club, centrifugal force bends the shaft and head towards you, especially on long clubs and trivially on short clubs. So a fairway wood with a 56 deg. lie, for example, would become more upright by about 1 deg. Many shops would have the player address the ball with club in hand and see if they could slide a 25 cent piece under the toe snuggly. If it passed too easily the lie was too upright. If it woudn't pass at all, then the lie was too flat. This was done in recognition of shaft bending in actual play. The better way of checking is to put tape on the sole of the head and swing normally on a mat. If the tape is bruised in the center, it should fit nicely. If it is in the heel, the club is too upright. If it is at the toe, the club is too flat.

 

Practically speaking, if you are a slicer and have trouble hitting to the left, a slightly upright lie may not be a bad idea. If your natural play is a draw, then you may have to be more precise in your selection. On wedges the clubs are so short to begin with that most players do very well with the standard lies.

 

 

The concept is to place the bulk of the weight of a given iron around the perimeter of the back to create stability, among other things, on off center hits. Although the idea is quite old, it has only been practical to make in the last 30 years or so. The principle is rather like that of a tight rope walker using a balancing pole on a high wire to counter any of his movements that might lead to a fall. It works in practice, just as it does on woods made of metal.

 

 

 

 

What is not generally known is the effect this concept has had on lofts. It is now easy to redistribute weight to the sole, thus lowering the center of mass, cm. This in turn increases the launch angle- you get higher shots. To restore a more normal launch angle, the loft is made stronger. As you have already observed from 3- above ( Loft & Lie Angles ) the lofts are much stronger today. Years back, a #9 iron was 45 deg. typically. Today 41 and 42 deg. #9 irons are common. The net result is the given iron also goes farther. ( Since metal woods are hollow, they have been designed similarly and they go farther for the same reason. ) Not many people buy or use #2 irons anymore because they feel the #3 iron does the job of a #2 and is easier to use as well.

 

There are skilled players who stick with the non cavity back designs because they prefer the "feel" and believe they can curve the ball to the left or the right more readily. However the preponderance of players seem to find the cavity back quite satisfactory. The benefits are:-

 

  - Less twist on off center hits.

  - Less slicing or duck hooks.

  - Straighter shots.

  - More distance.

 

Since wedges are "feel" or "touch" precision clubs, here we prefer the non cavity back designs, although a good case can be made for cavity back wedges by those who do not agree.

 

 

a-Torque

 

-The shaft is not completely rigid, and will twist during the downswing, and on an off center hit. Too much or too little can cause problems. Years back this was a big concern especially with graphite shafts. Good numbers were not yet established for the multitude of swing speeds and swing paths. Now the data has been gathered and the designs for various applications are pretty routine.

 

-The manufacturers call the twist factor "torque" and so rate their shafts in degrees of torque, such as 2.5, 3.0, 3.5, etc. all the way up to 7 degrees. The value is measured on a simple machine. The back end has a solid clamp where the butt of the shaft is firmly attached and cannot rotate. The tip is put into a second clamp that is horizontally in line . The second clamp can rotate as a unit and is firmly attached to the tip so it will rotate with it. A small weight is attached to the side of the second tip clamp and allowed to drop. The amount of turn is then measured in degrees and becomes the shaft's rating. Steel shafts tend to have less torque than graphite shafts, although very low values can be made in graphite as well. The complication in graphite is that as you take out the twist you may also make the tip a little too rigid for a good whip like release at impact. Fortunately most applications and most players do not require very low torque values and can employ graphite shafts in virtually all their clubs.

 

- In general, irons require lower torques than woods.

- In general any strong flex, x or s, requires less torque than r, which requires less torque than seniors, etc.

- Without some value of torque (that matches the player's swing) it would be very difficult to square up the head at impact, Too little and the head will arrive at the ball with an open face.

- It should be noted that many tour players use graphite shafts in their woods but often use steel shafts in their irons. Their powerful swings and great need for precision are special.

 

- Most players do not have to worry about torque, as the various suppliers have set good values that correspond well to the shaft flexes offered.

 

The sketch below illustrates, among many other things, how the shaft will twist when arriving at impact. Note that it can rotate either way before collision. If the shaft fits the player's swing, it will be rotating to a square position, trying to close, just at impact. If it does not fit, or the player makes a poor pass at the ball, it is unlikely that square contact will be made. It will twist either way on impact, as described in 10 above.

 

 

b-Other Motions

 

- As can be seen, the shaft will bend at its flex point. Flex points are located as follows:-

                  x-stiff      -          High

                  s-stiff      -          High

                  r-regular  -        middle

                  s-seniors  -        low

                  L-ladies    -        low

   The low position for the slower swingers give them some tip action needed to help accelerate the head and get the ball airborne. For the fast swingers, a low flex point would sling the head around, out of control. Consequently they need a high location.

  

 - It is also bending in, by centrifugal force, towards the player. This puts the actual lie at impact slightly more upright than the rated lie of the club. The difference may be as much as 1 deg. on a long club, although it will be insignificant on a short club.

- It is also bending along the target line, either lagging or leading. Fig.1 below shows the efect of a lagging shaft and head:-

 

 

 

 

 

 

 

- If the shaft is too stiff, the bend will be slight and the club head will be lagging with the face open at impact.  The path of the ball will be low and to the right.

- If the shaft is too flexible, the player will generally hit a high fade or slice. Here the shaft will also be lagging, the face also open, but the tip will be soft enough to turn the face upward, producing the high shot.

- The player could try to compensate for a too flexible shaft by hand and arm manipulation and release sooner. In that case the shaft and head would be excessively leading. He would produce a high and pulled hook.

 

 

 

-Fig.2 above is a well executed swing with the shaft and head releasing strongly and squarely, closing towards a hook position. This position is difficult to reach with shafts that do not match the player reasonably well.

 

- With a shaft that is too stiff, the player cannot do very much other than greatly improve his technique and swing speed.

 

- If the player has a shaft that is too flexible he can adjust his timing to match the slower responding shaft. Or he can choke down on the grip a little which will stiffen the shaft somewhat.

 

 

- Up to now, we have been looking at various conditions while assuming the club head was in a square position at impact. To complete the picture, it is necessary to explore what happens with the club head in other positions, as well as the influence of swing path on the results. The swing path the player uses will greatly influence the actual flight of the ball. Figures 1 and 3 below show two extreme paths, with the club head in a poor position, just at the moment of impact:- 

 

 

- Fig. 1 shows an inside to out path with a very closed face at impact. Most likely he is flipping his wrists, either trying to square the club, or is seeking more distance. This results in a smothered or duck hook, whether you strike the ball at the toe, or the center. At the heel, it might never get airborne. Were we to change the path to the outside to in of fig. 3 and keep that closed face, we would be looking at a pull to the left of some sort, depending on the point of contact on the face. It would also be a bad shot.

 

- Fig. 3 depicts the classic slicer's swing, with everything open at impact. The side spin would largely negate any of the benefits of face bulge and gear effect, no matter where contact was made. On a heel hit, a weak high fly is expected. On a center hit the player should find a classic slice with the ball drifting to the right without too much distance. At the toe it could be anything including a ground ball.

 

- Fig.2 is a square face and square swing path that should result in a good, on target, shot. If the player hits the ball at the toe or heel with this otherwise good position, gear effect will enter and keep the shot manageable. No one can always hit the ball in the center of the face, in line with the cm. This shows the importance of getting the club to a square position as much as possible. From this position you have a good chance of a reasonable result.

 

If your equipment doesn't fit you- if you are playing excessively stiff shafts- the odds of making a square to square path are poor.

 

Figures 4 and 5 below paint a different story:-

 

 

 

- Here we have an expert player maintaining a square face, while deliberately choosing a swing path that will curve the ball the way he wants.

 

- In Fig.4 we see a perfect draw swing. The target line shown above is down the middle of the fairway, for ease of drawing. In actual play, the golfer could well be aiming down the right side of the fairway, intending that the ball start that way and drift left. The point is that the face is square to his target line, whatever that may be, at impact. A small amount of side spin has been applied to the ball, because the face is crossing the ball slightly as it continues to go inside to out.

 

- In fig.5, we have the reverse- a perfect power fade swing. The head is square at impact and imparting a slight side spin that produces the fade. Please note that, all conditions being equal, a power fade goes just as far as a power draw, contrary to popular belief. Fades are not as long when the player executes poorly, and imparts too much side spin.

 

 

-Swingweight is an attempt to measure the distribution of weight throughout a club. It will show if the weight is towards the head, in the middle, or towards the grip. It has been theorized that if a set of clubs is made so each one has the same swing weight, then the "feel" of each will be the same as any other. The picture below shows the scale on which swingweights are determined:-

 

 

 

- The scale is rather like a see-saw, but the pivot is not in the center, but is located only 14 " from the grip end. Since the club is much longer than 14 ", as you place it on the scale, the head will droop towards the floor. The little balance device is then slid back and forth until the club is in balance and horizontal. On the side of the scale are swingweight numbers. The point where balance is made is the swingweight number, i.e. c-8, or d-2, etc. This scale of numbers is called the Lorythmic scale.

 

-Some have felt that lower figures would serve women best, while increasing numbers would apply to increasing swing speeds. Typically, c- 6 to c-9 was recommended for ladies; c-9 to d-1 for seniors; d-0 to d-2 for most men; and higher than d-2 for the stiff shaft players.

 

- This concept has limited value. Few can tell the difference between 1 or 2 points on the swing weight scale- can feel it.

 

 

-Offset is a design aid to combat the player's tendency to arrive at impact with the face of the club open. The hosel is set leading the club face. This problem is most severe on long irons and woods, due to their length. The sketch below shows a typical design for an iron (on the left) and a wood (on the right):-

 

 

-Today, irons are made around 1/2 to 1 inch longer than before. Consequently offset is being found in every club of the set, i.e., #3 and #4, 4 to 6 mm's, #5 and #6, 3 to 5 mm's, and the balance including the wedges between zero and 3.5 mm's.

 

- In the case of woods there are not many offerings that include any offset at all, even though offset was quite popular for higher handicap players until recently.

 

- In practice, the little extra gap between the hosel and the face gives the higher handicapper a much better chance of squaring the club face at impact. There are many low handicappers who are also using moderate offsets on their irons with great success too. It is most helpful on their #2 and # 3 irons due to the increased lengths prevalent today.

 

- For those players with a slice problem, who cannot seem to defeat it in spite of lessons, offset on their woods may be a great aid. This would be especially noticeable on the driver, it being the longest club in the bag.