QA Get Into the Grooves


Editor's Note: This is the latest in a weekly Q&A feature from The Golf Channel's Chief Technical Advisor Frank Thomas. To submit a question for possible use in this column, email
I have heard that the grooves on the wedge (sand and lob) wear out. How can I check my wedges to know if I need to get a new one? Can you explain the difference between the different type of grooves U, V, Y that are available? -- Scott Strool

The Y groove is really a U groove which is milled into the face with a Y-cutter which means that the edge of the groove close to where it meets the face has a slightly different angle than the side of the groove lower down in the groove. The V and U shaped grooves are named this way because of their cross sectional shape. The U groove has also been called a square groove and now also a Y groove.
In 1984 the USGA adopted a modified groove rule I wrote, which allowed grooves to be U-shaped. The requirement used to be V-shaped with very precise specifications which required flat sides and specific angles with the face plane. You can imagine, that a groove which is limited in size to be no more than ten pieces of standard computer printer paper, is very difficult to get perfectly V-shaped unless it is rolled or stamped into the face. This used to be the case with forged clubs but most clubs are made from castings and have to go through five steps before the final product emerges. So the shape of a V grove is compromised to look like a semi U-groove.
The Square or U grooves are intentionally U-shaped and will affect the spin on the ball out of light rough but not 4-inch rough or even perfectly dry conditions.
The grooves will need attention when they are visibly worn and the edges are flattened down. It is important to keep the grooves on your wedges in good shape and if you play a lot you may have to have them re-grooved every two years or so. If you use your sand wedge exclusively out of the bunker then dont worry about the grooves as a good sand shot always has sand intervene between the face and the ball and the grooves dont play a significant part in the control of this shot.

Follow this link to to see our report Frankly The Best Wedge, obtained from a survey of over 1,100 golfers who owned, used and rated their own wedges. This report also contains some helpful technical advice on what is important when choosing a wedge.
Are so called, 'frequency matched shafts' just so much snake oil, or are there real benefits to be achieved by golfers of varying abilities? -- Boris E. Meditch

The best shafts for you are those which meet your flex requirements i.e. Regular for most of us (80 to 90 mph head speeds): Stiff for the faster swingers and X-Stiff for the really fast swingers. Once you have selected the right shaft flex then it is important that the shaft be symmetrical in its bending properties and each shaft in the set is from the same flex batch (so-to- speak). Most of the shafts selected by manufacturers for standard sets are very good and just fine for 95% of us. The elite gofer may want a different shaft with slightly different torsional properties or flex points etc. but the difference in performance is so small that most of us are unable to detect it, unless you play for a living and practice 4 to 8 hours a day.
Most of us have a performance variance, significantly greater than any differences that we can detect in standard shafts variation.
Frequency matched sets of shafts are generally more consistent in their bending properties than others but again not enough for us to tell the difference between a frequency matched set and a good set of standard shafts. Getting a frequency matched set is like balancing the wheels on your car for speeds of 150 mph. If you get to this speed then you might be able to tell the difference. Most of us dont have cars that can go much above the top speed limit.
However, it is comforting to know that if you ever get the car up to 150 mph your wheels are balanced for these speeds.

While watching an episode of Whats in the Bag? a clubmaker was talking about a pro for whom he was building clubs. He said the pro had X-stiff shafts in his irons right now and felt they were too stiff so they were building clubs with stiff shafts that were tipped. Saying this would make the shafts stiffer than stiff but less than X-stiff. What do they mean and what do they do?

As you decrease the length of a shaft or increase the diameter it will feel stiffer and the club will have a higher frequency i.e. it will vibrate faster if clamped in a vice at the butt end all else being equal.
You have probably experienced this when you stick a knife in a crack in the picnic table (dont do this at home on the dining room table) and pluck it so it vibrates.
A knife with a thick blade will vibrate faster than a knife with a thinner blade. Or, if you stick it deeper into the crack in the table, it will also vibrate faster.

So if you shorten a shaft in your club (generally from the butt end) it will feel a little stiffer. Or in the case at hand if you thicken (increase the size) of the shaft it will become stiffer.
In this case the club maker has taken a standard shaft and instead of cutting it to length from the butt end where there is hardly any taper he has trimmed it from the tip end. As shafts are tapered this has increased the size of the shaft in the lower section. This is the smallest diameter and most flexible section of the shaft. So the more you take from this end of the shaft the stiffer the shaft will become, even though you havent decreased the overall length.
So to increase shaft stiffness, tipping is a common method but it does make the shaft tip-stiff and will slightly affect the flight of the ball by decreasing the spin and launch angle.
I have 2 equipment questions. 1. At PGA tournaments, are the balls that the players hit at the practice range all the same brand, or do they each hit the same brand that they use in the tournament? 2. What would be the effect of having irons that are too upright or too flat? -- Bert

From experience or actually developing a guide book for How to Operate a Championship Practice Range now updated and used by the USGA, I can tell you that until about fifteen years ago there was only one ball type being used and selected because it was the most popular ball on tour. This has changed and there are now up to five different ball types provided to the tour players for practice.

These golfers are very good and in many cases can tell the difference in flight trajectories between the premium balls.
With regard to your question about upright irons, the face of an upright iron will be point to the left (if you are right handed) of the target and tend to draw the ball. The reverse is true for flat irons. Because most amateur golfers tend to slice the ball, manufacturers prefer to build clubs with upright lies.
Frank Thomas, inventor of the graphite shaft, is founder of Frankly Golf, a company dedicated to Helping Golfers. Frank is Chief Technical Advisor to The Golf Channel and Golf Digest. He served as Technical Director of the USGA for 26 years and directed the development of the GHIN System and introduced the Stimpmeter to the world of golf. To email a question for possible use in an upcoming Let's Be Frank column, please email