Driver: stamped loft vs. measured loft

[SecondShot]

I wonder what the gap is for your driver between the stamped loft and the measured loft. My new M5 driver got measured today and I was (positively) surprised that the loft is 1 degree stronger. Do you have your numbers?

TaylorMade M5: stamped 9° - measured 8°

[geochitown]

Face angles?

[storm319]

MyGolf$py includes this in their annual driver test so you can see which brands vary more than others based on that single sample. +/- 1 degree is a fairly standard tolerance with large US OEMs. In defense of the OEMs, bulge and roll as well as non flat soles makes definitive loft measurements difficult so that is part of it.

Ultimately getting closer to the stated loft would increase the cost beyond what most people in the US would be willing to pay (golfers in Japan are willing to pay a lot more for precise specs hence the reason why the JDM stuff is a lot closer to spec and more expensive).

[Howard_Jones]

Static loft measured at the center of the face is not really that interesting unless thats where you make impact, and all heads on the marked has face ROLL, and the ratio vary A LOT, and that means some heads has a spread of more than 4* depending on height on the face we measure (up to 6* as loft difference, thats why we can see launch angle differences of up to 4* depending on where we make impact) .

I play Wishon 919 THi where stamped loft is 11.0*, so is measure loft at 0.5 closed FA. and this heads has whats called Graduated Roll Tech, so the lowest 2/3 of the face is constant 11.0* while the top of face is plus 1.5* or 12.5*

So loft itself at the very center dont mean a lot, its the area you make impact that does, and for drivers we can use the formula Loft * 0.85 = launch angle as a rule of thumb.

 

 

[SecondShot]

He just measured the loft.

[Stuart_G]

When it comes to drivers and woods, the word "loft" can have multiple meanings and some depend on face angle. Did he measure the Static loft or Effective loft? If the later what was the hosel setting? If the former, was the naturally soled position of the head found correctly? And on top of that, accurate measurements require the individual measuring to have enough training and experience to correctly measure the loft on the curved face (roll of the face).

[SecondShot]

The guy who measured it is one of the best club fitters in Germany. Hosel setting was normal (standard). He mentioned it isn’t that easy to say how much it has in real because of bulk and roll / twist face. The 8 degree was measured static in the center of the face.

[Stuart_G]

It may not be as easy to tell the difference of which loft was measured just by observing. In this case 'static' isn't nessesarily what it sounds like. Well it is but both static loft and effective loft are both measured statically (as opposed to a dynamic loft).

Static loft is where the loft is measured with the head in it's naturally soled position. The face is typically not square to a particular target line like when iron lofts are measured. It's left at it's naturally open or closed position depending on the head design. Adapter setting generally doesn't matter and in fact, it's more typically measured w/o the shaft installed at all although the shaft doesn't have to be removed.

Effective loft is measured the same way loft is measured with irons. The face is not necessarily in it's naturally soled position, the face is forced square to the target line, the shaft has to be installed and the hosel settings do matter.

The two are only the same when the natural face angle of the head is zero - perfectly square. (not typically the case with TM heads - but can't say I've measured the M5 myself to verify that).

The two can look the same by an observer, the main difference is whether the face was adjusted square before measuring or left in it's naturally soled position.

 

 

 

[Howard_Jones]

Thats all correct Stuart, but you make it sound more complex than it really is, so let me add a few lines to make confusion total. :-))))

We can use this chart, both to convert the clubs static loft in its naturally soled position with a open or closed face angle to "effective loft", AND for hosel adjustments, AND to judge the heads loft at impact (without shaft bending and AOA)

The conversion gear ratio depends on LIE ANGLE, so lets use 60* as example.....

If the head we have fall 1.5* open or closed, and loft is measured in that position, the one with 1.5* closed would be 1* higher as effective loft (square face angle), and the one that falls open at address would be 1.0" lower on loft when face angle is square, since the ratio at 60* lie is 1.5* face angle to 1* loft

The same for Hosel adjustments, if we have a hosel where we can close or open face angle, and lie is 60*, we need 1.5* change of face angle to get 1* as difference to loft.

But here is the problematic part...whats your face angle vs path at impact? thats the actual loft you are playing, so a player who plays a draw, need a closed FA vs path to make it, and the player who plays a fade needs a FA open to path to make it, and more closed at impact = Less loft present, and more open = more loft present..(just like with a wedge we play open)..We can use the same chart again, so a Draw made with a face angle 1.5* closed to path will play with 1* less loft than measured square or as "effective loft".

 

Example my own driver and my preferred ball flight a small draw.

Static loft was measured to 11.0* with a FA 0.5* closed, but as average i meet the ball with a face angle 1.5* closed to path, and lie angle on my head is 58*

I will now have to look at 58* lie, and the loft difference for 1.0* extra closed FA = 0.71 so my loft at impact on a center hit is 11.0 minus 0.71 = 10.29*

Since my head was measured with FA 0.5* closed, we can now use the same chart to see what loft would be square, and lie is still 58* so the 0.5* closed took away 0.71/2 = 0.35* and that means the head i play would measure 11.35* with face angle square or as "effective loft" (who is a silly term, since thats NOT the position of the head at impact, in my case its actually about 1* lower since i play a draw)

 

[Adam C]

I measured 5 Taylormade M5 drivers earlier in the year, all at the same time. All of them were within .5 degree of the 9 stamping. Personally if you don't have numerous samples to measure at the same time, your measurements will be suspect at best. TaylorMade and every other OEM doesn't tell you where they measure from on the face so all you can do is estimate. I was able to lock in my 4 point gauge so I consistently measured the same place on the face every time. This is of the utmost importance.

Also the whole face angle argument gets into the weeds. I am sorry, but if you are measuring in anything other than a square face, you again will have suspect data. I wouldn't measure a 6 iron with an open face even if it fell open at address, I would measure with a square face. Why should a driver be any different? Answer, it shouldn't. These types of measurements require eliminating as many variables as possible, letting face angle come into the equation makes for a big variable.

I will also say that the twist face makes it much harder to get consistent measurements so that might have been part of your club makers problem.

[Stuart_G]

Why should a driver be any different? Answer, it shouldn't. These types of measurements require eliminating as many variables as possible, letting face angle come into the equation makes for a big variable.

 

It really doesn't add a new variable. The face angle will be an important spec whether it's included with the loft measurement or not. The chosen method for measuring loft wont change that. The important thing is understanding what method is used and being consistent when matching or picking specs. The only real difference between irons and woods is that without a useful 'naturally soled position' and therefore a useful face angle spec, the distinction between the two methods disappears with the irons.

 

As for why it has been done that way, it's not all that hard to understand. That's how wooden heads were made, at least that's my understanding. I can't say I ever made a wooden head myself. The loft is carved into the head before the shaft bore is drilled or installed so it's the only way the one doing the carving could accurately measure the loft through the design and manufacturing process. Then variations in the drilling of the bore would translate to face angle changes and inconsistencies instead of loft. Effective loft is only available and measurable after a shaft is installed.

 

As for what method 'should be' used, I'll leave that for everyone to decide for themselves. The are a lot of aspects of club building and fitting that should be nice if they were standardized - measuring length, shaft stiffness, etc... but complaining about the lack of standards doesn't usually accomplish much. The best we can do is understand the differences so we can work effectively with them.