What Are Grooves Really For?

[Middler]

You can find lots of articles that suggest replacing wedges every 75 rounds because you lose spin as grooves wear.

You can also find lots of articles that say irons have grooves to clear water and debris, and not to generate spin. Some even test irons with and without grooves and find little difference in spin under dry/clean conditions.

Which is right? Could the former argument be face wear and not groove wear (making both true). There are lots of articles stating either argument, here’s one of each.

https://golfingtree.com/why-do-golf-clubs-have-grooves/

Quote

A common misconception about golf club grooves is they are meant to give the ball spin.  This was my assumption until I did some digging around and discovered a guy by the name of Ralph Maltby.  Ralph performed an experiment to debunk this by making clubs without grooves and playing with them.

https://www.titleist.com/teamtitleist/b/tourblog/posts/when-should-you-replace-your-wedges

Quote

The Vokey R&D team tested three levels of groove wear using a proprietary wedge robot at the Manchester Lane test facility. The results? Wedges with fresh grooves lead to more precise shots. We recommend that every golfer should evaluate their wedges and grooves at ~75 rounds of play to get the best spin performance.

 

[Hook DeLoft]

I assume groove wear decreases the volume of the groove, thus meaning there is less space for water and grass etc to go.  Which in turn means more water and grass between the ball and the face.  That would be why worn grooves decrease spin.  Grooves would have little effect on a driver.  As far as Maltby's experiment, being able to play well without grooves is different than saying there isn't a difference in spin between irons with and without grooves when hitting a ball off the grass.

[McGolf]

every designer i have talked with have said grooves are there to allow debris to move away . meaning dew, grass etc.

[Kenny B]

19 minutes ago, McGolf said:

every designer i have talked with have said grooves are there to allow debris to move away . meaning dew, grass etc.

What are all those little white flecks stuck in my wedge grooves?  

[ncwoz]

46 minutes ago, McGolf said:

every designer i have talked with have said grooves are there to allow debris to move away . meaning dew, grass etc.

Yep, this is it

Grooves are like little "trenches" that help divert moisture, grass, debris, etc. So the grooves don't "make" spin, but more accurately maintain the spin when other stuff gets between the ball and the face. In the absence of that "stuff" a grooveless face would likely spin more, because of the increased surface area and thus increased friction.

One helpful analogy I've heard is in race car tires - when it's dry they'll use "slicks" which are smooth, but when it starts to rain, they'll use "grooved" tires to divert the water away.

On the subject of replacing wedges after grooves are worn; it's because the wedge doesn't divert the "stuff" as well or (more accurately) as consistently anymore, so spin rates will be lower as the stuff gets more in the way. 

[ballhawk]

Apparently the USGA would most likely disagree with grooves don't impart spin, other wise there would be no clubs (irons) on their "not legal" list.