TECHNICAL

CLUBHEAD SLOT TECHNOLOGY

A video explanation behind the technical basis for the slot head technology seen on a number of head models in the industry today, as well as how a slot head compares to a thin face or variable thickness face design.

 

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Kevin Read
5 years ago

Did you ever get the results back with the combination slot and variable thickness face? Would love to know the results.

Tom Wishon
5 years ago
Reply to  Kevin Read

KEVIN I did design a prototype of a driver with both a slot design and variable thickness design and one other face enhancement. Testing on this showed that the slot and additional face beveling did nothing to add to the major face performance element of the variable thickness face. Which is pretty much what I expected. There really is too much metal and distance from the edge of the face to the slot for the impact to be able to cause the slot to flex in anyway. A think straight section of metal extending from the edge of the face… Read more »

Talen
8 years ago

Is it possible to design a wood head that has both slot technology as well as a variable thickness face? In theory wouldn’t that give you the benefit of both worlds?

Tom Wishon
8 years ago
Reply to  Talen

TALEN: IT’s interesting you had the same thought after viewing the explanation of current slot head technology. I did too when I was in the middle of the shooting of this video. So within a week after I finished the video, I sent one of my production factories a model and a design for a driver prototype that not only had a variable thickness face, but had slots all 360* around the face AND a cup face construction with a special and very new type of bevel around the edges of the face. All these elements on the same prototype… Read more »

keith usher
6 years ago
Reply to  Talen

Thinking of the head flexing, if a club just has a top slot if you hit high in the face and just the top of the club flexes then will a very small degree of lift angle be added from static to dynamic as the ball is struck? So if you have slot on the sides will this not add dynamic face open and closed angle on off center hits? So I would conclude your face flex to be better than rear of face perimeter flex for directional control of off center hits.

Tom Wishon
6 years ago
Reply to  keith usher

KEITH Using slots in the body of a hybrid or wood head to try to enhance the flexing of the face has some very limiting factors involved. First of all, it is highly doubtful that very many of the slot type heads even allow the face to flex inward more. LOTS of variables are involved there – how thick is the head from the edge of the face to the slot, how thick is the metal in the slot, what is the metal the head is made from and what is its final yield strength, and then a big one… Read more »

keith usher
6 years ago
Reply to  Talen

I think the slot probably makes that part of the club stiffer as it will be thicker and like adding ribs to a flat sheet of metal. I picked up one of your 525 FD’s, I believe this has no roll and helps stop a low face hit being de-lofted. Its working well so far! (my sterling irons should also be built by january) Thanks for your time and effort on all your designs

Tom Wishon
6 years ago
Reply to  keith usher

KEITH How a slot works or if it even does depends completely on the yield strength and thin-ness of the metal in the curved area of the slot itself. The slot itself is really constructed just like a spring in that it is a 180* curve of metal. But if the wall thickness of the curved area of the slot is thicker and or made from a higher yield strength metal, then the slot acts like a stiffening brace to in essence do nothing to add or change the face’s flexing. If however the wall thickness of the slot is… Read more »

SteveT
8 years ago

Tom, why not just determine the load displacement on a clubface when placed in some kind of compression test bed apparatus that will simply apply a constant and concentrated load over various points on the clubface and allowing the face to flex freely? Perhaps a concentrated load of say 100# will adequately depress the clubface, and then move the load around the clubface to determine the differences. The amount of yield can be easily measured without resorting to dynamic testing and the resultant “smash factor” over the club face. In this way you can verify the differences between the slot… Read more »

chris
8 years ago
Reply to  SteveT

Steve: You do not have to do anything even close to what you are suggestion to determine for sure if the slot heads do anything to change the ball speed or the smash factor. Smash factor with a good launch monitor tells you everything you ever want to know about whether a slot head OR ANY HEAD TECHNOLOGY has the ability to increase distance for any golfer, for any impact location. Smash factor is directly correlatible to COR of the face. COR is directly related to the amount of face flexing and energy transfer to the ball. You cannot fool… Read more »

SteveT
8 years ago
Reply to  SteveT

Chris…. I understand the indirectly calculated correlation between Smash Factor and COR, but what I was suggesting is a direct way to measure clubface deflections over the entire clubface with an applied static point load. In this manner you can directly measure the deflections at any point on the clubface without resorting to hitting a golf ball subject to Hertzian deformation.
Just press down with a concentrated load on any point on the clubface and see how much it yields, thus uniformly comparing the slot face and variable thickness face deformation under controlled loading.

chris
8 years ago
Reply to  SteveT

Steve:
We do pretty detailed and sophisticated FEA on face designs from lots of work in this area over the years so we are quite confident we know the amount of face flexing for our head designs. This is one of the ways we have been able to correlate the modeling to the results when we see the actual hitting tests with robot and Trackman. so here again, there is no real reason to change the way we look at these things because it would just come out with the same results.
Thank you,
TOM

Kelly L.
8 years ago

Tom,
Nice video about the slot technology. I was a bit surprised that you didn’t mention the PGA COR mandated limits in your video. It seems to me that, with the COR limits, design isn’t nearly as important as the limit itself. Now, if your argument is that slot technology won’t achieve the same COR as the variable thickness design, then I would understand that, but I didn’t hear that in the video.
Definitely appreciate the website and all of the great information you provide.
Kelly L.

Tom Wishon
8 years ago
Reply to  Kelly L.

Kelly Thanks much for your interest in viewing the video. The reason I did not clearly or unequivocably say that the slot heads do or do not have their COR up at the limit of the rules, or say specifically what their COR is, is because at the time of shooting the video I had not gotten any of the OEM slot heads to actually test to say exactly what these parameters are. But since then I have had the chance to test two of the OEM slot heads and on these two particular ones, the COR for robot hitting… Read more »

Juan L. Furquet
8 years ago

Hi Tom, Very interesting article…but what is your opinión about the technology employed by Ryoma Maxima with both crown and sole flexing at impact.Last Christmas , the day after the night before I parted company with nearly US$2,000 and bought one of these, replaced the Crazy Boron shaft for a 55g Wishon S2S White and I am hitting it longer than any of my wide arsenal of drivers.Not only me but also my teacher and a scratch golfer who happens to be my nephew. In my opinión Ryoma with their system are fooling the 0.83 COR rule because it is… Read more »

Tom Wishon
8 years ago

JUAN: No matter what method of head and face design is used to try to increase the ball speed of a shot, the measurement of the smash factor by a good launch monitor tells you precisely how much energy and distance a head design can generate. Smash factor is the ball speed divided by the clubhead speed. For a clubhead with a precise 0.830 COR, the smash factor cannot be more than 1.495 when the ball speed and clubhead speed are both measured perfectly accurate. I have yet to see, and I have been told by many clubmakers who have… Read more »