Understanding Golf Club Grooves

Aug

2007

Understanding Golf Club Gooves

Posted by Double Eagle in Equipment, Rules

Grooves on the faces of our golf clubs are something that we might take for granted.

With irons, especially wedges, the grooves help put spin on the ball when it is struck. This allows us to hit shots into greens that stop in a controlled manner.

When we strike the ball with a descending blow with an iron, the ball becomes briefly trapped against the turf and is “pinched”. The grooves on the club grab the cover of the ball and impart maximum spin. That allows the shot to land softly and stop quickly or even back up after landing.

There is no question that equipment has changed the way the game is played at all skill levels. Players have gained distance, accuracy, and the ability to stop the ball quicker.

Consequently, all aspects of club design come under scrutiny and regulation. Club grooves are no different.

There has been debate for a long time about square (or, u-shaped) versus v-shaped grooves on irons. According to a United States Golf Association news release from February 2007, a technical report released to club manufacturers in August 2006 by the USGA and the Royal and Ancient Golf Club (R&A) shows:

“The research findings clearly demonstrate that for shots struck by clubs from the rough with urethane covered balls (the type of ball used by most highly skilled players), modern square or U-shaped groove clubs result in higher ball spin rates and steeper ball landing angles than V-shaped groove designs that were predominantly used in the past. The combination of a higher spin rate and steeper landing angle results in better control and less difficulty for shots hit from the rough to putting greens. As this degree of difficulty for shots hit from the rough has decreased, the importance of driving accuracy on the PGA Tour has lessened. “

In that release, the USGA proposes two amendments to existing groove rules:

The total cross-sectional area of a groove divided by the groove pitch (width plus separation) would be limited to 0.0025 square inches per inch.

Groove edge sharpness would be limited to an effective minimum radius of .010 inches.

That will have the effect of making square grooves perform more like V-shaped grooves. If you like to dig into club specs, you can read the proposal online, including a comparison of current versus proposed regulations(PDF), as well as the groove measurement procedure(PDF).

The reason I bring this up now is that the deadline for submitting comments to the USGA about the proposed rule changes was yesterday, August 1, 2007.

My expectation is that the rule will be enacted and the effects will be felt on January 1, 2009 when any competition committee will have the option of enforcing the new rule, and we’ll all feel it starting on January 1, 2010, when all new conforming clubs will be required to adhere to the new specifications.

Recreational players have no-doubt gotten used to the extra stopping power and won’t be happy when new clubs don’t perform the same way that they’re used to.

I’m not sure how this will affect play on the Tour. The rise of “bomb and gouge” has seen players start to just swing away and hit the ball as far as possible, knowing that they can still spin it from the rough and stop it on the greens. Will they go back to putting a premium on accuracy over distance again? Maybe. Or, maybe they’ll still figure that a sand wedge out of the rough with dumbed-down grooves is still better than an 8-iron from the fairway.

Time will tell.

Oh, and one side note: did you know that the grooves on the driver are strictly cosmetic? Those shots require as little spin as possible and are struck with a level or slightly ascending blow. You’ll notice that the grooves on the face don’t normally cover the sweet spot. Consumers must not respond well to clubs with completely smooth faces, I guess.

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Read More:

Since I wrote this originally I found a good post from The Wedge Guy giving some of his thoughts on the USGA groove proposal.

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There are currently 17 responses to “Understanding Golf Club Gooves”

1
HappyRock said:

I really liked the information and insight in that article. I enjoy reading about some of the depth to golf that you don’t normally see from a duffers perspective.

Posted on August 2nd, 2007 at 2:52 pm
2
Double Eagle said:

Thanks, HappyRock. I like digging in to the details and understanding the small stuff.

Posted on August 2nd, 2007 at 3:18 pm
3
Rookie said:

Sir or Madam,
I read the entire article you wrote. And while it is very well written, it also provides incorrect information. The grooves on a golf club’s face are not responsible for imparting spin on a golf ball. The purpose of grooves on a golf club are to filter away dirt, debris, and moisture from the ball. The spin comes from club faces being perfectly flat. The grooves move the dirt, debris and moisture away from the ball, and the perfectly flat club face is the reason for the spin. The illegal clubs faces are parts of the reason for their spin in some cases because they’re very abrasive and they actually grab the ball and do impart spin. But, on a legal golf club the spin comes from the face being perfectly flat and the grooves moving anything away from the ball. This is the reason for the groove roll back, and is also the reason you don’t see top wedge manufacturers using aggressive milling on their club faces.

Posted on March 23rd, 2009 at 11:29 pm
4
Double Eagle said:

Rookie,

You’re partially correct, but also partially wrong.

It’s true that grooves help to divert moisture and grass. That’s why U-shaped grooves provide more spin when hitting from the rough. The U-shaped grooves have more volume than traditional V-shaped grooves, and thus can deflect more grass and moisture, providing better spin from the rough.

However, I could not disagree more with your statement that grooves are not at all responsible for imparting spin.

For more information, I recommending this gallery article by Dave Pelz: http://www.golf.com/golf/gallery/article/0,28242,1882070,00.html called “Cracking the Wedge Spin Code”. In his books and in that article, he does affirm that contacting the ball with a descending blow to avoid trapping grass, dirt, and moisture between the ball and the club face. However, on slide 11, he also states: “In order to generate the highest possible spin rate, you need to play a ball with a cover soft enough to be engaged by the grooves in the clubface.”

He goes on to point out that greater spin is achieved with urethane-covered balls versus surlyn covered balls, because the softer urethane is more able to be engaged by wedge grooves.

This isn’t to say that grooves are the only, or even most important factor in creating spin. For instance, a proper swing that promotes ball-first contact is probably the most important. Also, friction on the face from the milling process can be responsible for spin. The line of wedges Dave Pelz produced with Jesse Ortiz has a special milling on the face to keep a higher spin rate for a longer period of ownership. Clearly, the added friction of a rough face contributes to spin.

At the same time, “pinching” the ball against turf or hardpan is a major source of spin which comes from the club face “grabbing” and deforming the ball, and the grooves play a part in that.

Posted on March 24th, 2009 at 12:32 am
5
Rookie said:

I have read the article by Pelz, and he is a good teacher, but he is not a club designer or club maker. If you think the grooves are responsible, I’d like you to contact Joe Kwok, whom is a club builder. He’s on golfwrx.com’s forums. Ask him about the results of an aggressively milled face with aggressive grooves versus the traditional wedge he did. The one with the flat face and standard grooves spun more. I don’t subscribe to Pelz’s dictatorship like theories on golf, and he’s a real pain in the you know where in person. I’ve talked with him before and he was one of the most rude people I’ve ever met. I’ve seen the golf magazine article as well, am a subscriber, I still don’t agree with it.

Posted on March 24th, 2009 at 11:28 am
6
Double Eagle said:

Actually, Rookie, Pelz has designed a number of clubs since the 80’s, including the wedges he teamed up with Jesse Ortiz on, that I mentioned previously. That doesn’t necessarily make him all-knowing on the subject, but it’s not fair to say he doesn’t have some understanding of club design.

I never disputed that face milling has a great effect on spin. In fact, it may be fair to say that it has a greater effect than grooves. However, I have seen or read nothing that would lead me to believe that groves have absolutely no effect on spin beyond diverting grass and moisture. If there are published studies on this matter, I am more than interested in reading them.

I mean absolutely no disrespect to Joe Kwok, but I don’t know him, and maybe that’s my loss because I don’t live among the club design/maker circle. But reading this kind of debate in forum threads is mostly counter-productive because I have no idea who is sitting on the other side of the screen. If there are books, magazine articles, trade papers, or scholarly publications, then I’m more than happy to read up and then change my tune. If you can point me to any of those things, I’d love to read more about it.

Regarding Pelz, whether he is a nice guy is irrelevant. I’ve never met him but it’s clear that his ideas, teaching, and experimentation are highly respected at the highest levels of golf. Since the beginning of time, there have been a-holes in every field, but it doesn’t normally take away from what they do. It’s nice to be liked and respected, but you can be respected and not liked and it doesn’t affect the bottom line.

I’m also not sure it’s fair to call his techniques “dictatorship-like”. I mean, did he show up at your door and tell you that you had to play the short game his way? He says what he thinks is correct (and as we know in golf, there is very little that has to be done one way to be “correct”) and people either listen or they don’t.

Posted on March 24th, 2009 at 11:55 am
7
Rookie said:

Simple science should explain it for you. If the grooves are the part of the club that impart spin, then why do spin rates change among an iron set? It’s fair to say that the vast majority of manufacturers, I’d venture to say, precisely mill the grooves on the face of their irons to the exact same depth across the set. So why does a pitching wedge spin significantly more than a 3 iron? It’s not the grooves, it’s 2 things, face angle(loft) and flatness of the face. The flatter face and the higher loft of the club, the more spin. Why? Because the ball spins up the face and is in contact longer due to the loft, imparting more spin. The grooves do have an effect on spin, just not in the sense that they grab the ball. They move dirt, debris, and moisture away from the ball allowing it to be in complete contact with the face and to spin up it.

A simple analogy? Think about a ping pong paddle. Take one that has a flat face and one that has the rubber bumpers/texture to them. The one with the smooth face will spin more. Why? Surface area. There is more surface area for the ball to be in contact with at one time for it to spin across. Why do you think professional ping pong players all use smooth faced paddles?

The groove roll back wasn’t due to the fact that they impart more spin. It was because they funnel more dirt, debris, and moisture away from the face of the club, especially in the rough. So yes, they do have an effect, just not in the way most people think. They allow the ball to be in complete contact with the face of the club and allow it to stay in contact longer, increasing spin.

Posted on March 24th, 2009 at 11:05 pm
8
Double Eagle said:

I read the post again to be certain, but I don’t think I ever disputed (and still don’t) that the USGA’s groove roll-back was intended to stop higher spin from the rough and that the higher spin from U-shaped grooves comes from the deeper grooves diverting water and grass, not from more grabbing. I’m not disputing that.

But, I’d have to say that the faces of all my irons are perfectly flat, so I’m not sure how that factors into the equation. By that logic, I would expect that since my wedges are less flat than the rest because they are the most worn (no doubt a little concave), then my 5-iron would impart more spin.

Clearly it doesn’t for the simple reason you gave: loft. I never disputed that. But since none of my irons is flatter than any other, I fail to see how flatness is a factor. Another factor that needs to be considered is a descending strike, as well.

It’s easy to say that this is all explained by simple science. So far, you’ve given me analogy and not much science. By that, I mean scientific results. Certainly, with the debates that rage on this topic, someone must have done some actual research on this topic that has been put out somewhere?

Without that, you’re asking me to just accept what you’re saying as fact. I genuinely mean no disrespect, but if we’re going to dismantle conventional wisdom, let’s do it with the scientific method. Please don’t insult me by saying, “Simple science should explain it to you,” without presenting me with some, as if this issue is somehow as clear as the fact that the sun will rise tomorrow. If it was, there would be no debate among well-respected people in the field, when clearly there is debate.

Posted on March 24th, 2009 at 11:38 pm
9
Rookie said:

You want science and physics? How about an independent study done by Dave Tutelman, owner and president of Tutelman Research, and formerly of Bell Labs? That can be found here: http://www.tutelman.com/golf/design/swing2.php?ref= Scroll down to the part titled SPIN in bold. And more importantly, scroll to the part that begins with Grooves in large type.

Another thing to read is from Bill Gobush, whom happens to be a researcher at Titleist. It’s Bill Gobush, “Spin and the Inner Workings of a Golf Ball”. The article is in “Golf The Scientific Way”, a collection of articles edited by Alastair Cochran and published by the Aston Publishing Group in the early 1990s. Gobush is a researcher at Titleist, and is one of the worlds experts in measuring and modeling golf ball behavior.

The article looks at what happens to the ball at impact, and how that imparts spin to the ball. It shows how the design of the core of the ball can affect how much spin results from impact.

You wanted research to back the data up, those are two of the foremost researchers on the planet regarding golf, especially the relationship between the ball and the clubface at impact.

Posted on March 25th, 2009 at 4:04 pm
10
Double Eagle said:

Excellent! That’s all I was asking for. Not unreasonable, right? I will review and make any appropriate changes to the post and to other posts that discuss spin and grooves.

Posted on March 25th, 2009 at 4:21 pm
11
Bob Kelley said:

Intersting discussion on grooves. Might be worth contacting the clubmakers and designers at Golfsmith for their input. When attending a clubmakers class, the instructor I had subscribed to the trash/debris school…the grooves move stuff out of the way so the clubface can make a cleaner contact with the ball..so that loft and angle of impact can come into play. U and square cuts have more volume to collest moisture, grass bits, etc. to keep the club face cleaner.
The articles referenced seem of value…thanks for the discussion site.

Posted on April 2nd, 2009 at 3:07 am
12
ABGarcia said:

Rookie, I think you need to reconsider your opinion of Dave Pelz.
If you get a chance to read his Short Game Bible, he explains
quite clearly what the grooves on golf clubs do for your swing.

FYI, Dave Pelz has a college degree in Physics and he worked for NASA
before he became a PGA Teaching Professional. I think a guy with that much education and experience along with being a lifetime golfer knows what puts backspin on a golfball.

Simply put, hard steel clubface with a sharp groove edge and/or milled face will dig into a soft cover ball more and provide more backspin than a smooth clubface and/or smooth groove edges, guaranteed. This assumes a decent swing speed, more speed equals more backspin, guaranteed. This is fundamental physics, guaranteed.

While you may not have liked Dave Pelz personality, he may have found your ignorance of basic scientific principles annoying.

Posted on April 25th, 2009 at 10:09 pm
13
Double Eagle said:

ABGarcia,

While I agree with your points on Pelz, I must say that as I’ve been digging through the references that Rookie provided, I’m intrigued by what I’m seeing. Specifically, I was led to The Search for the Perfect Swing, which I’m currently reading.

It’s a summary of a scientific research project (targeted at the layman) conducted in the late 1960’s. There’s a section in there that discusses spin. They do support the points Rookie made, and to me the most interesting fact they point out is that the club meets the ball with something like a couple thousand pounds of force (that’s a ball park figure as I can’t recall the exact number). Stated a different way, that’s like saying that from the point of view of the clubhead, the ball weighs like 2000 pounds.

The point they make is that with that much force between the club head and ball, that any gripping power that the grooves provide is almost irrelevant to the production of spin. It’s kind of like dumping a bucket of water in the ocean and taking credit for helping to flood some island somewhere.

They ran tests with irons with completely smooth faces versus irons with normally grooved faces and found that the production of spin was almost the same. I believe the grooved clubs put an ever so slightly greater amount of spin, but it was a small enough difference as to be virtually negligible.

Posted on April 25th, 2009 at 10:53 pm
14
CHUCK said:

What if I am using a set of clubs from Mid 1990’s. Hey I have tried to change, can’t seem to be able to find a set that I can hit as well. Anyway, HOW can we find out / determine if these older clubs have U Grooves or V Grooves without sending them to some MicroMeasurements Lab?

Posted on July 6th, 2009 at 1:22 pm
15
Double Eagle said:

Chuck, I’m not sure if it’s something that can be eyeballed or not. Unfortunately, I don’t have any wedges to compare that are older than 5 years or so.

However, it’s probably not really something to get too concerned about, unless you’re a professional or play competitive amateur events. The USGA isn’t going to adopt the groove rule in most of its championships until like 2014 and recreational players won’t have to think about it until 2024.

Posted on July 6th, 2009 at 9:56 pm
16
CHUCK said:

Well I’m sure not a professional, not playing in any USGA Amateur events. But every now and then you have a “SmartA**” in your foursome that doesn’t want to pay up the friendly bet because of an illegal club. LOL Read the rule book “Shankapottamus”. At current pace of trying to find a set to replace my old Cobra Oversize it could be 2024 before I am able to find some. I have 3 sets of clubs in my garage I really need to get listed on ebay i guess. Thanks for the response.

Posted on July 7th, 2009 at 11:13 am
17
Barry said:

Well, here we are in 2010 and “the rule” is in place.

The usga face roughness rule is based on a thing called “Roughness Average”. RA, in the best way possible, is a complex formula that takes into account the “texture” of a surface and the overall “waviness” of the surface, then averages that out. The USGA rule is 180 RA. This is equal to the raw surface created by a typical forging process or a very good casting process of metal. Pretty logical choice for our sport. The results are “decorative” areas on the face of irons that are now pretty smooth compared to years past when we had those grinder wedge faces, which made the rule change, btw.

As for grooves, well those equally spaced cuts on my ball with those shaggy bits of cover material hanging from them aren’t from nasty birds attacking my ball in their territory.

The real answer is a little bit of both. Golfballs only “see” mass and acceleration. You can make them go with a rock tied to a stick. As for putting some spin to it, well, certainly, there is frictional rotation applied but far less these days than before the USGA face roughness rule changed. Then there are those little slits in the ball cover after contact to account for. Oh, Golfsmith did some testing years ago and grass in your grooves makes a 5 to 15 yard loss of distance due to reduction in spin. That’s aerodynamic lift reducion due to loss of backspin from clogged grooves and that was with V grooved 8 irons!

Go figure which is the most important of the TWO aspects of spin.

Posted on February 18th, 2010 at 12:30 pm

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