MOI of a golf club, where did it go?

[BREWMASTER95060]

 

Hogan ptx

irons I added weight to shafts to make a SW and MOI match.

all lead tape added near(needed to SW MATCH) 14 inches from butt.

[Howard_Jones]

How does your total weight progression from club to club looks like?

[Noodler]

The "Sting Stoppers" look to be just like the foam backer rod you can buy at Home Depot. You wouldn't be able to add weight to those I don't think. The original Sensicore inserts might work since they're like a foam spiral wrapped around a straw (you could put tungsten powder in the straw possibly).

I am using these: https://www.golfworks.com/lead-counterweights-for-steel-shafts/p/cw/

The addition of the weight at the 14" point is highly suspect. It's just not "aligned" with MOI/MBI matching theory. It only makes sense from a swingweight matching perspective. It might make some sense to add the weight at the original balance point of the shaft when measured alone, but I have not yet tested that idea.

[Howard_Jones]

Adding weight 14" down from the grip makes no sense what so ever, not even within the SW system. What we know about the SW system is that it provides a progressive resistance as we go longer, but adding weight on the scales fulcrum fools the system and the SW scale, because its NOT a "neutral point" in play.

Adding weight on the shafts BP is just like using a shaft with more weight, so you can see the effect using Montys app by manipulating shaft weight.

Im afraid some users of both MOI and MBI forget that Total weight has a limit and is more important, so if we overlook total weight and TW progression from club to club, we want be able to make a set that feels right, so never overlook total weight, thats where most who fails did the mistake. I learned that the hard way about 10 years ago, but experience that most who build clubs still dont pay attention to total weight at all, its just a value where they ended up, it was not a plan at all behind that value, it became like it did due to other priorities of less importance like MOI or SW.

[Howard_Jones]

@rx7mark
If iron head weight is higher than wanted on some heads, you are forced to build to a higher MOI than wanted and that makes no sense, and its very easy to reduce head weight by hosel drilling, so let me explain how we do that and avoid issues.
If the need for removal is above 5 grams, we should use a drill press and a hosel fixture, if its less than that we can do it free handed. We start with a study of the hosel, and judge how long is the hosel from BBGM and down (drilling area), before the hosel no longer is a full cylinder, but becomes D shaped. The area between those 2 points is no issue what so ever and is the "safe drilling dept" all the way to the largest drill IF we use a hosel fixture.
Below that point, we must reduce drill bit size, but dont forget, we always start with the smallest drill bit and go forward in steps, NEVER go strait on using the largest drill bit from the start.
To judge the need for drilling dept and drill bit size, you can use this charts with both imperial and metric drill bits.
Use a TAPE mark on your drill bit so you are in control of drilling dept. Set the tape mark at INSERT + DRILLING DEPT so you can stop drilling when the tape is in level with the hosel top. Up to 10 grams can be removed from most iron heads, for wedges way more since wedges has a higher BBGM and a longer Cylinder (safe drilling dept) than irons has.
The 9/32" drill bit is easy to use as example, it removes 1.00 grams for each 1/8" drilling dept, so if the needed removal is 5.0 grams, we need a drilling dept of 5/8", but always start by using the 1/8" down to that level first, then use either a 3/16" or a 1/4", the finish the job using the 9/32" as the last. 5/16" who is the largest drill bit we should use only need 4/8" drilling dept to remove 5 grams, and most iron heads has a BBGM of 1.25" and "safe drilling dept" is often up to 7/8" when using a drill press and hosel fixture.
[img]https://s3.amazonaws.com/golfwrxforums/uploads/BGRR4FNT4GGP/image.png[/img]

[BREWMASTER95060]

Hi Howard,

ideally 12 grams per club= 7 per head + 5 per shaft.

 

 

[Howard_Jones]

If i understand you correct, you have a total wgt progression of 24 grams pr inch? (4/8" between clubs)

[BREWMASTER95060]

 

YES

AND

HERE IS AN EXAMPLE:

NOTE: I BOUGHT THE HEADS USED 9, GAP AND WEDGE HEAD VERY CLOSE IN WEIGHT.

HEAD WEIGHT, SHAFT WEIGHT, SW AND MOI.

MBI CLOSE

 

 

[BREWMASTER95060]

YES

[BREWMASTER95060]

 

2 Dynamic gold wedge shafts

2 Dynamic gold 38.5” shafts with senscore

3 FST 125 shafts

 

HERE IS AN EXAMPLE

NOTE 9, GAP AND WEDGE HEADS CLOSE IN WEIGHT

 

HEAD WEIGHT, SHAFT WEIGHT, SW AND MOI.

MBI CLOSE

shaft length

33 5/8

34

34 1/16

34 5/8

35 1/8

35 9/16

36

 

[rx7mark]

Howard,

Thanks so much for this very informative post.  I now am armed with the knowledge to lighten a head if a future builds requires it.

I really appreciate you sharing.

Mark

[Howard_Jones]

I suggest using a drill press if this is a job you will do often like i did, its actually faster to reduce head weight on a few heads, than it is to use tip weights for most of them where we ends over target...the reason is, when using tip weights you will have to adjust a bit on the tip length itself, equal to the amount the tip weight "shims up" the shaft in the hosel, and that takes time on a precision build where we want play length to be "correct" without the small variable the tip weight moves PL to the longer side.

For a hobbyist who makes clubs to himself, plus friends and family only, a drill press like this one is "good enough" and dont cost much, its the hosel fixture that blows the budget unless you are the handyman type who knows how to build your own tools.https://www.wish.com/product/5aaa32afe114ef0a03cbc687?hide_login_modal=true&from_ad=goog_shopping&_display_country_code=DK&_force_currency_code=DKK&pid=googleadwords_int&c=%7BcampaignId%7D&ad_cid=5aaa32afe114ef0a03cbc687&ad_cc=DK&ad_lang=EN&ad_curr=DKK&ad_price=111.00&campaign_id=9527731167&gclid=CjwKCAjwsan5BRAOEiwALzomXxrbcECq-8lq3dzOTldomwVK6b5YJXPJjFLBi-elusolwwjuKkniVRoCj7cQAvD_BwE&share=web

Dave Tutleman have a idea for a DIY hosel fixture.https://www.google.com/search?q=golf+hosel+fixture&sxsrf=ALeKk01C9D-g8IqwthDhDaV5gIfU6UD4PQ:1596623093106&tbm=isch&source=iu&ictx=1&fir=pSZT9X6Vdab84M%252CnBqrCan73uFBCM%252C_&vet=1&usg=AI4_-kQX9N78XT89jw_S0hxAzg_jNpwFCA&sa=X&ved=2ahUKEwizwLfC7IPrAhW_AxAIHS9vBXIQ9QEwA3oECAoQCw&biw=1280&bih=578#imgrc=pSZT9X6Vdab84M

 

[rx7mark]

Noodler did a good job of answering your first question, as to the second, the most weight I have added to a shaft is 16g.

[rx7mark]

The Golf Works reaming and boring vise seams like a reasonable solution for a hobbyist like me at $69, and I have a cheap drill press similar to the one you linked to.

[Noodler]

Howard - I don't think there's anything in club making that you don't have a table for!

[Noodler]

As I gave more thought to adding weight to shafts to achieve MBI matching, I determined that it boils down to 3 options:

Add the weight as a backweight at the end of the shaftAdd the weight as an aux weight at the balance point of the shaftAdd the weight as an aux weight at the balance point of the shaft+grip assemblyI slept on these 3 options and I believe that it is option 3 that has the most probability of being the right choice. The reason I believe this is based on what you see with the overall club balance point in an MBI matched set. The club BP as a percentage of the overall club length is "proportionally equal" in MBI matched sets. This means that when you divide the club's BP by the club length you get approximately the same value for all the clubs in the matched set. This is not seen in non-MBI sets. The percentage instead increases from the long irons into the short irons. I think that this truly is the "heart" of what MBI matching is about; it provides the build approach that creates clubs with the same proportional balance point along with matching MOI. This is what truly duplicates what we call "feel" when swinging a club.

The only option for the addition of weight that makes sense if you consider the proportional balance points is the 3rd option. I will be testing my theory by building 3 clubs; each using one of the options. I will build them all to the same MOI/MBI combo and match them to a club I already have (the "control" club). Then I will determine through actual play which of the 3 options best matches the feel of the "control" club. I'll do my best to keep the overall club weights equal too.

Where are you putting your money?

[games]

First, sorry to divert the thread. I'm just a mid-cap hack with nowhere near the knowledge the active participants in this thread have. But, my nature is analytical, and I would play my best with clubs truly "optimized" for me. Further, I believe my local fitter / builder would understand the concepts you are discussing.

What is the practical application of the concepts discussed here as it relates to a fitting and purchase? In other words, what do I request from my club builder? MOI? MBI? Or ???

Thank you all!

[Noodler]

I would be surprised to find a "typical" builder that understands these concepts if they have had no prior experience using the MOI/MBI methodology.

Understand that what we've been discussing in this thread is primarily about the build process, not the fitting protocol. The primary challenge when fitting a golfer for MOI/MBI builds is the determination of the best values of MOI/MBI for the particular golfer. This requires a bunch of test clubs (or the ability to spin up clubs of varying MOI and MBI values easily and quickly). Then the golfer tests their ability to achieve center-strike accuracy and optimize club head speed. None of this is the usual approach of most fitter/builders. These days most of them use a trial-and-error process where they just swap out components and decide what looks best on a launch monitor. It's just not in the same realm of fitting at all.

[kam39]

rx7mark,

I'd pulled up his post early yesterday morning before there had been any replies and added the link for the shafts but didn't finish before getting sidetracked. When I went to close out my open tabs, realized I hadn't actually hit "Post Comment" and didn't see your reply with your build specs until afterwards.

ALCON,

If anyone is interested, I came across two U.S. patents yesterday (i.e. what sidetracked me) that outline approaches to correlating/matching clubs in mass, 1st moment, and 2nd moment about an axis with clubs that have different lengths. The first patent was issued to Vance Elkins back in 1978 (filed in 1975), who founded the Sounder Golf Company (https://patentimages.storage.googleapis.com/8b/34/40/e036657135da12/US4128242.pdf). The second patent was issued to Theodore Jorgensen in 1983 (filed in 1981), author of "The Physics of Golf", (https://patentimages.storage.googleapis.com/fa/0f/7f/a9d92685df573f/US4415156.pdf), which outlines the process he talks about in his book (Chapter 11, "The Matching of Clubs" & Tech Appendix Section 2).

[Howard_Jones]

Oh yes there is a few i actually gave up on.....Total weight progression is one of them, its the strangest specs of them all where we often get flabbergasted about what we see, so even if i love charts and "systems", one of the most important club specs of them all has so many varieties we can hardly find a system in it, and since that subject is of highly importance, let me share a few thoughts about that.

From the old fashion descending weight shaft, trough constant weight to ascending weight, we will see a total weight progression that vary with A LOT and like this, still using the SW system and 4/8" between clubs. Dynamic Gold Descending wgt, DG Constant wgt and AMT White is used as examples.

Descending wgt #3 to #9 = 32 grams over 3 inch = 10.5 grams pr inch

Constant wgt #3 to #9 = 42 grams over 3 inch = 14 grams pr inch

Ascending wgt #3 to #9 = 60 grams over 3 inch = 20 grams pr inch

If we MOI match this sets, we can take the short cut and use 8 grams as head weight progression, that moves the slope for Descending weight to 38 grams over 3 inch or 12.66 grams pr inch, the Constant wgt set moves to 16 grams pr inch and the AMT set moves to 22 grams pr inch.

When we start to mess with alternative play lengths, the chaos gets complete, where even a constant wgt set can get above 28 grams pr inch if we go down to 5/16" between clubs as MOI matched, so if you are able to "see a system" in this jungle so a chart can be made....be my guest :-). The only system (if any) is that "most players" fits to play sets where total weight progression is between 14 and 18 grams pr inch, but with so many exceptions that we can hardly call it a system, its not even a good rule of thumb, at the best we can see it as "the direction the wind blows", but we all know that the direction of the wind might change during the day and it often does...

This is the reason for why i asked @Brewmaster about his Total weight progression pr inch, i have actually never seen players that had a progression as high as 24 grams pr inch, it seems very steep, but the only valid rule in the end is...what ever works for the player....

So, even if i tried to carve out a "system" or chart for quick reference to identify clubs that was OFF on total weight, i gave up on it, and that was before i tried to add shafts with different balance points into it all, and if we included them too....ANY progression rate seems possible, so navigating in one of the most important parameters of all, hardly have guidelines to follow, thats the crazy thing about it, so i often asked myself, How do others navigate here?...seems like most take it on "walk over"...total weight is a product of all the other parameters we hardly ever look at before the player experience issues with it.

[Howard_Jones]

Its quite clear that Jorgensen knew his stuff well (physics), but has no clue about how golf clubs works.....strong words i know,(and im perfectly aware of who he is) but listen to this.

He is using the #7 iron as master club, we would call it "favorite" club, or the club we wants the other to become a copy of, so when he tries to match the #1 iron to become like the #7 iron, here is whats needed....

Head weight reduction 31.2 grams (cant be done without re-designing the club head, we cant modify a standard head that much and get away with it, just ask those who tried to make their own single length sets)

Shaft weight addition. 82.2 grams, placed about midway between the head and his point of rotation of the club, 5 inch from the grip end. I cant see how we would be able to modify shafts to gain 82 grams on a spot close to the middle of it, some type of insert maybe. Total weight GAIN on the #1 iron is 51 grams, but with a very different location

His idea might be good on the paper, but it demands components designed this way, it dont look like something we can do, even if the example was using True Temper shafts and Tommy Armour heads. He might have been able to make the model, but that set would not be playable. (again with a reference to DiY single length sets using standard heads)

He even had to raise total weight in his master club with 15.9 grams 5 inch below the grip where he has the point of rotation, and then he has failed bad for the simple reason that the master club is no longer the master club, but demands a modification many players would complain about. Grips of today has their balance point at 4 inch from the butt, so just ask a player who went from a standard 50 gram grip to a 66 gram Mid size plus 4 grip if they still think the club feels the same???.....thats the never ending SW scale debate

My conclusion is, Jorgensen tried to solve a math puzzle with identical total weight, but the same dynamic MOI for all clubs. Thats interesting enough, but it really makes no sense to "match" a set thats not matched to the player, (it would fail just like the MOI matched Tommy Armour sets did) so when he needed to alter his "favorite/master club" even his theory fails and is no longer valid since we need the "coincidence" of a Master club using a 66 gram grip as point zero. The other 2 issues, adding that much shaft weight can probably be done, but removing 31 grams form a club head without destroying that club heads properties of VCOG and RCOG is easier said than done, so not even me who can grind club heads from blanks would try this.

But thanks for the input, its interesting enough, very interesting actually, but close to impossible for most people to make based on what components we have access too. I really think what we have up for debate is extremely interesting as a whole, but Jorgensens idea is the hardest of them all to bring to life....

PS if a #1 iron head back then was following the same pattern as today, it would have been 225 grams, and the need for removal was 31.2 grams or 13.87%. His examples dont cover the #3 iron, but the options i see is limited to hosel drilling (about 10 grams as the max), and B-Weighted heads (minus 7 grams), sum reduction about 17 grams of a need of 31, so we are 14 grams off the realistic target for head weight (fast estimate), and still have to figure out how to get more than 80 grams added to the shafts right below the center of it.....

[JCAG]

Thanks but fortunately I retired some 18 years ago after owning a very successful custom club shop. I know quite a few successful clubmakers that pulled the plug on their businesses.

[kam39]

Howard...I totally agree with your points, although Jorgensen does refine his thoughts and process for the design of clubs further in his book. He is an academic though, not a club manufacturer or builder. If you don't currently own a copy of "The Physics of Golf, 2nd Ed" I'd recommend picking up a copy on the used book market as its an interesting & different perspective to the game of golf. One reason I posted the link to his patent was so people on this forum could compare it with Elkin's patent and thought process. The added benefit is the patents aren't marketing campaigns, but provide both the science and problem they are attempting to solve iot get an exclusive monopoly for 17 years on the invention. At worst it is simply "food for thought" even if neither succeeded commercially.

[Howard_Jones]

Vance Elkins ideas sound achievable, but i did not get to read it all, but what i did read did not turn on any warning lamps like Jorgensens ideas who might be good, but like i wrote, demands that club heads and shafts thats redesigned and thats not for us deadly folks at all, so i will leave that as a theory only. When we consider Theodor Jorgensens influence on Golf in general, the BIG question is, why aint Golf clubs made the way he thought they should be made?

Elkins on the other hand was interesting, and i mentioned a Norwegian i was liking to a few pages back in this tread....sounds like he has been reading Elkins patent and added some NASA stuff about our body mass to make it "a new idea", but Elkins talks about our body to, so it seems clear where "mr Biomatch" got his idea from, its not NASA, thats a distraction...

 

[BREWMASTER95060]

FOR NOODLER

MY MONEY

"Add the weight as an aux weight at the balance point of the shaft+grip assembly"

[Noodler]

@games - I'm quoting my own reply post to you to emphasize a point I missed in my original response. I just had 4 rebuilds go through my "shop" over the past week or so and two golfers made some interesting comments that I think may help you. It's important to understand that an MOI/MBI build creates a set of clubs that are quite different than how they "operate" when they're swingweight matched. I believe that many golfers attribute characteristics to their clubs that are actually inherent to the build, not to the specific components. A rebuild using the very same components can completely "revitalize" a set of clubs if the rebuild provides a better fit for the golfer. So don't make the mistake many golfers do and blame problems on a particular head or shaft. Those very same components can be made to play very differently if you take them to a fitter/builder who understands and uses the MOI/MBI build methodology. It amazes me how many of my golfing buddies continually "move on" to new sets of clubs forever hoping for something better, but not truly understanding the variables in play when it comes to the weight distribution of the components and the MOI/MBI impact if there are significant variances across the set of clubs (as is typical in swingweight matched sets).
If you don't have 8 hours a day to practice golf, then it only makes sense to consider the MOI/MBI build approach that can create a set of clubs that work for you, not against you.

[BREWMASTER95060]

These are some of my hogan ptx irons I bought new.

put on different grips

add lead tape and sw and moi matched.

[Big Eric]

On 8/5/2020 at 8:47 AM, Noodler said:

...

The only option for the addition of weight that makes sense if you consider the proportional balance points is the 3rd option. I will be testing my theory by building 3 clubs; each using one of the options. I will build them all to the same MOI/MBI combo and match them to a club I already have (the "control" club). Then I will determine through actual play which of the 3 options best matches the feel of the "control" club. I'll do my best to keep the overall club weights equal too.

Where are you putting your money?

@noodler

Did you ever do this experiment? I'm rebuilding a set with constant weight taper tip shafts and want to be able to get the MBI match closer.

 

A second question if you don't mind. Any tips on how to pick the best MBI? The set I'm rebuilding has MBI  that varies from 31 in the 5 iron to 39 in the wedges. I built them using Monte's spreadsheet several years ago thinking that the MBI was close enough. Reading this thread makes me want to dial in the MBI. Would picking the iron I hit the best make sense and adjust the rest to match that MBI?

 

Thanks in advance.

[Noodler]

31 minutes ago, Big Eric said:

@noodler

Did you ever do this experiment? I'm rebuilding a set with constant weight taper tip shafts and want to be able to get the MBI match closer.

 

A second question if you don't mind. Any tips on how to pick the best MBI? The set I'm rebuilding has MBI  that varies from 31 in the 5 iron to 39 in the wedges. I built them using Monte's spreadsheet several years ago thinking that the MBI was close enough. Reading this thread makes me want to dial in the MBI. Would picking the iron I hit the best make sense and adjust the rest to match that MBI?

 

Thanks in advance.

 

Unfortunately I never did the investigation because as I previously noted, I honestly believe intuitively that the 3rd option is the correct method (adding the weight to the shaft+grip assembly's balance point).

 

Choosing the best MBI is exactly what you're proposing.  Take a bunch of clubs with known MBI values and see if there's a pattern in your ability to find center-strike accuracy and great results.  The real key though with MBI is to make sure you are testing clubs that are across the club categories of driver, woods, hybrids, irons, and wedges to truly see/prove that the chosen MBI value is optimal.

 

[Seattlegolfnut]

I built a set of clubs a year back with Monte's great gcv2p5 spreadsheet. Recently picked up an Auditor as I'm intending to built another set.

 

Checked the old clubs on the Auditor this weekend. The irons were planned at 2710 and all measured -10/+5 MOI points so I consider that successful.

 

But the hybrids, 5W, 3W, and Driver are measuring high to what the spreadsheet calcs predicted. ~20 points high for the hybrids, and 40-60 points high for the woods. Driver for example was planned at 2800 and measuring ~2860.

 

Scratching my head why. I was meticulous in weight and measurement, consistent in gear and technique. I also calibrated the machine a few times and the fact irons are good leads me to think something is off in the calculated estimates.

 

The adjustable hosel adapter strikes me as the one difference in the build between the irons and hybrids/woods. I assumed it should be measured as part of the head in my calcs, so I basically screwed an adapter on the head prior to glue. Was that the right way or should I have made it part of the shaft?

 

Any thoughts?