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Manufacturing Tolerances in Golf Clubs

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golfunfiltered

golfunfiltered

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Saw some chatter on social the last few days regarding the variance in manufacturing tolerances, which was surprising to me (both because people were talking about the topic, and the range of variance itself).

To level set: every product that is produced by humans (h/t @JB for the reminder) has a range -- or tolerance -- where specs might differ from what is considered "standard" or documented for that product. For example, a driver that is stamped with 10.5 degrees of loft might be measured to have 10 degrees or 11 degrees. However, there can be wider ranges as well.

It's important to remember that what is stamped on a golf club might only tell half the story, especially when discussing something like loft. It's equally as important to know how those manufacturing tolerances impact metrics like carry distance. This all further amplifies the need to get custom fit, to know your equipment as well as you can, and to not take things for face value.
 
This is a very interesting discussion. We measure every head that comes into THP HQ in the Club Lab and sometimes things are a bit off. Most of the time, they are really close. I wonder when fitting/testing how much that weighs into people's thoughts.
 
To be completely honest it's not something I have ever really thought about. Every manufacturer has tolerances that are acceptable. If they passed their quality control why should I care if its .5° off from what is stamped on the club? Does it really matter to the average golfer?
 
jdtox said:
To be completely honest it's not something I have ever really thought about. Every manufacturer has tolerances that are acceptable. If they passed their quality control why should I care if its .5° off from what is stamped on the club? Does it really matter to the average golfer?
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Maybe? Probably not with fitting, assuming you are fit into the exact same head you are getting. If that makes sense.
I played with an older gentlemen that had a driver from a component company and he lives in my neighborhood. He hits it well but really low. He asked me to regrip his driver and when I did, I measured it. His 10.5 driver was actually just under 9 degrees.
Or better yet, if people judge "rankings" and "lists" as the ideal situation for providing data, what if the lofts are not the same, rather than what they are stamped. To give you an example, I got 3 heads from a company earlier this year that were up to 2 degrees off in either direction.
 
This is something I've never even thought about until recently (with clubs and balls). For instance, I've never had my lofts checked after the season. Even if the clubs were in spec from the manufacturer, with use they can become out of spec. It's definitely something to consider when receiving a new set, and since I often by used clubs, I probably need to check specs.
 
JB said:
Maybe? Probably not with fitting, assuming you are fit into the exact same head you are getting. If that makes sense.
I played with an older gentlemen that had a driver from a component company and he lives in my neighborhood. He hits it well but really low. He asked me to regrip his driver and when I did, I measured it. His 10.5 driver was actually just under 9 degrees.
Or better yet, if people judge "rankings" and "lists" as the ideal situation for providing data, what if the lofts are not the same, rather than what they are stamped. To give you an example, I got 3 heads from a company earlier this year that were up to 2 degrees off in either direction.
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Obviously that component company doesn't have strict QC in place if they are that off. I would like to think/hope that the larger OEM's would have better QC than that because 2° is a huge difference. Maybe I'm wrong in thinking that but its just not something I've ever really put that much thought into. Short of having a club that is way off from others I've never even had something like that checked.

FWIW I do believe that being fit into the actual head you will be purchasing is a smart thing to do. How many times do you hit something well at a demo day or similar and purchase a club off the rack and its completely different?
 
Every manufactured item has tolerances! No I would not notice something that is .5 deg off but if I had a driver head that is stamped 10.5, had it checked and it was like 9 deg then that to me is NOT in tolerance. Same goes with the irons, if they were like 2 deg off (weak or strong), then yeah I would not be happy with that and even know I may not notice the loft discrepancy as a mid handicapper or so I would expect better! They should be able to control tolerances better than that, especially with the cost of these clubs!
 
I recently had a friend with a Mitchell lie/loft machine check a couple of iron sets for me and some of the differences to what I thought those specs were was quite eye opening. A lot of the differences were in excess of 2 degrees which shocked me and the clubs played quite differently once I had them set to the specs they should have been.
 
Strictly speaking about golf clubs only, it's encouraging to remember that those tolerances (for the most part) can be adjusted or corrected. Half a degree might not make any significant difference in performance, but some of the examples offered in this thread definitely would.
 
How does this work with tolerances of the face? I know Taylormade uses the injectable polymer to bring them legal, but for other brands would that mean some of their heads would be illegal with being over 460cc and too much spring of the face? Or is this more an issue with loft and lie?
 
pumbaa said:
How does this work with tolerances of the face? I know Taylormade uses the injectable polymer to bring them legal, but for other brands would that mean some of their heads would be illegal?
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This is an excellent question and not one I'll pretend to know how to answer. @vgolfman would definitely be the best person to reply.

An educated guess: I'd imagine if it's a variable in manufacturing, then there is a calculated (and measurable) risk for defect.
 
When we purchase a club we all assume (at least I do) that the club will be within tolerances, but how do you know other than the reputation of the manufacturer? Is custom fit the answer to be 100% sure?
 
golfunfiltered said:
This is an excellent question and not one I'll pretend to know how to answer. @vgolfman would definitely be the best person to reply.

An educated guess: I'd imagine if it's a variable in manufacturing, then there is a calculated (and measurable) risk for defect.
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Not speaking for any OEM, but most will have some CT’s over the USGA limit due to tolerances and a desire to be as close to or at the limit on as many heads as possible. I worked at a company (then fairly small in driver sales volume) that checked every head for CT. Expensive and time consuming and not realistic for most companies today.

With the limit at 257 CT limit (239+18), it’s common to set the manufacturing standard in the high 240’s to the low 250’s and have a +/- 10 tolerance. Depends on the company, their willingness to risk the % over and both their in-process and final quality checks. Face and face opening lip thickness and other process checks as well as manufacturing method (milling versus human polishing) can reduce the CT tolerance. The lower the tolerance (or more risk own is willing to take on) can lead to a higher nominal standard CT’s.


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I know things can be out of spec. I don't have anywhere to verify any of the specs though. I cannot say in all of my years that there was a club that played drastically different than what I expected of it. So, I haven't really worried too much.
 
wedgeman said:
When we purchase a club we all assume (at least I do) that the club will be within tolerances, but how do you know other than the reputation of the manufacturer? Is custom fit the answer to be 100% sure?
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vgolfman said:
Not speaking for any OEM, but most will have some CT’s over the USGA limit due to tolerances and a desire to be as close to or at the limit on as many heads as possible. I worked at a company (then fairly small in driver sales volume) that checked every head for CT. Expensive and time consuming and not realistic for most companies today.

With the limit at 257 CT limit (239+18), it’s common to set the manufacturing standard in the high 240’s to the low 250’s and have a +/- 10 tolerance. Depends on the company, their willingness to risk the % over and both their in-process and final quality checks. Face and face opening lip thickness and other process checks as well as manufacturing method (milling versus human polishing) can reduce the CT tolerance. The lower the tolerance (or more risk own is willing to take on) can lead to a higher nominal standard CT’s.


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One question I have regarding the CT test:

(If I'm describing this correctly) the old COR test used a regulation golf ball fired at a club at 100mph, and the club was legal if the speed of the ball rebounding off the club stayed at or below 83mph.

Is the CT test configured in a way to replicate the force of a 45g ball striking a club face at 100mph (yes I'm mixing units, but you're an engineer so.... :alien:) or is there some "fudge factor" between the two tests where a club could pass the CT test but fail the COR test?
 
JohnSinVA said:
One question I have regarding the CT test:

(If I'm describing this correctly) the old COR test used a regulation golf ball fired at a club at 100mph, and the club was legal if the speed of the ball rebounding off the club stayed at or below 83mph.

Is the CT test configured in a way to replicate the force of a 45g ball striking a club face at 100mph (yes I'm mixing units, but you're an engineer so.... :alien:) or is there some "fudge factor" between the two tests where a club could pass the CT test but fail the COR test?
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Yes a club could pass CT but fail COR.
 
JohnSinVA said:
One question I have regarding the CT test:

(If I'm describing this correctly) the old COR test used a regulation golf ball fired at a club at 100mph, and the club was legal if the speed of the ball rebounding off the club stayed at or below 83mph.

Is the CT test configured in a way to replicate the force of a 45g ball striking a club face at 100mph (yes I'm mixing units, but you're an engineer so.... :alien:) or is there some "fudge factor" between the two tests where a club could pass the CT test but fail the COR test?
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The old impact COR test and current CT were a correlation, not a true equivalency. They took COR data and correlated it to CT data to produce an equation/chart for figurative equivalency.

Yes, it is possible (and highly likely) that certain technologies could get around the old COR and be conforming to CT. The USGA has completely done away with even the possibility of COR tasing anymore. So, pass CT and good to go.


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I guess the next question would be how far past the old COR limits could we see designs go? I would think the correlation would be close enough to yield only 1 or 2 MPH above the old limit....maybe?
 
JohnSinVA said:
I guess the next question would be how far past the old COR limits could we see designs go? I would think the correlation would be close enough to yield only 1 or 2 MPH above the old limit....maybe?
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Total speculation... maybe 1 mph.


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When I went to the Callaway Ball Speed Blitz, I thought I remembered that Callaway tests their Epic Flash Driver an insane amount of times for CT before it ships.
@JDax is that something you remember as well?
 
markm778 said:
When I went to the Callaway Ball Speed Blitz, I thought I remembered that Callaway tests their Epic Flash Driver an insane amount of times for CT before it ships.
@JDax is that something you remember as well?
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They talked about testing and how each club goes through 4 different tolerance test before it able to be sold.


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I'm gonna need someone to explain the correlation between COR and CT to me, and if one "causes" or impacts the other.
 
Back to the original assumption that fitting is even more important when you take the affect of manufacturing tolerances into consideration.

JB said:
Maybe? Probably not with fitting, assuming you are fit into the exact same head you are getting. If that makes sense.
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How often are you going home with the club you hit during your fitting? I would guess that would be pretty much never, at least at the kind of fittings I've done. So lets's just say Brand X has an acceptable tolerance of +/- .5* from the stated loft on a driver. You figure you wouldn't see a significant difference with .5*, but what if the head in the fitting cart was +.5*, and the one you receive is -.5*? That's a full degree difference, and could have a significant affect, even though you were fitted into that driver, that 1* might have put you in a different shaft.
 
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golfunfiltered said:
I'm gonna need someone to explain the correlation between COR and CT to me, and if one "causes" or impacts the other.
Click to expand...

COR was the actual measure, using light gates, of a ball fired into a club head (face specifically and obviously) and its speed following impact. The math is a little more complex, but if a ball is fired at 100mph into a head and then returns at 83mph, the COR would be 83/100 = 0.830.

CT, which stands for characteristic time, is a measure of how long a pendulum stays in contact with the face from different drop heights and therefore velocities.

Again, the USGA then correlated the results of CT to max COR driver heads, along with many other COR driver heads values, to come up with essentially (albeit greatly simplified here) of 0.830 “equals” 257.


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wedgeman said:
When we purchase a club we all assume (at least I do) that the club will be within tolerances, but how do you know other than the reputation of the manufacturer? Is custom fit the answer to be 100% sure?
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Even custom fit won't do it. What you're getting fit with and what you ultimately order could (in the extreme case) be at the far end of tolerances.

With some - Ping, for example - it's possible to request a club with the exact loft specified. And you can be fairly certain that most of the heads in tour vans are similarly tested and marked.

In general though tolerance is something that an OEM has the ability to specify at the foundry. They can say that they'll accept anything that's 1.5 degrees off or 0.1 degree. The tradeoff is that the latter will result in more scrap and that cost is going to be passed on to the OEM.
 
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