MOI of a golf club, where did it go?

[Stuart_G]

24 minutes ago, Seattlegolfnut said:

 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?

 

Yes, adapters should be considered part of the head.

 

Any MOI calcs are going to be estimates at best.   There is no direct way to accurately calculate it.  The actual MOI depends on a detailed mass distribution, not just on c.g.'s.   The biggest errors tend to come from the variations in mass distributions in the shaft.  Also, the bigger the head, the more chance for inaccuracies (less accurate the c.g. is as a predictor). 

 

[Seattlegolfnut]

3 minutes ago, Stuart_G said:

 

Yes, adapters should be considered part of the head.

 

Any MOI calcs are going to be estimates at best.   There is no direct way to accurately calculate it.  The actual MOI depends on a detailed mass distribution, not just on c.g.'s.   The biggest errors tend to come from the variations in mass distributions in the shaft.  Also, the bigger the head, the more chance for inaccuracies (less accurate the c.g. is as a predictor). 

 

Thanks Stuart, I appreciate that confirmation on the adapter and reflection on the calcs vs. reality.

[Seattlegolfnut]

On 7/22/2020 at 12:22 PM, Noodler said:

I may have missed it, but how did we get into this discussion where the "wheel" is being reinvented? Monte already had all these discussions way back when on the Wishon forum and worked with quite a few people to vet the process he defines in the gcv2p5 spreadsheet. I own an MOI Auditor and using Monte's build process I am generally within 5 MOI points of the build plan for the completed club. Monte's spreadsheet does make a few assumptions to simplify the process, but his BP method to determine the CG of the most critical components just plain works. No need to get crazy when the work has already been done.

I'm really far off from +/- 5 MOI points of the build plan and completed club.

 

I'm also new to using the machine, but well versed in the physics and theories of MOI and MBI (thanks to this thread and others!).

 

I'm trying to ascertain if the machine isn't working right, my technique is bad, if the 45* F temperature in the garage has anything to do with it (everything is acclimated so doubt it), the longer clubs having graphite shafts while the others are steel, or if like @Stuart_G said, I should just expect the estimates to be that -- just estimates and trust the measured values. 

 

Feels logical to go with the measurements, but it confuses me that @Noodler said he was within 5 MOI and Monte mentioned in his MBI spreadsheet theory on accuracy that he rarely measured a completed club because these estimates were darn close when holding 0.1g and .02cm. I pretty confident I'm there with my analytical balance (calibrated with an F1 class weight) and the metric ruler in similar setup to the pics in the spreadsheet.

 

I know this is all just numbers, and I'm not intending to chase a specific MOI number. I just don't know if I'm doing something wrong in the spreadsheet or the measuring, and that bugs me. 🙂

 

 

 

Edited February 7, 2022 by Seattlegolfnut

[BREWMASTER95060]

On 8/6/2020 at 2:00 PM, BREWMASTER95060 said:

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

put on different grips

add lead tape and sw and moi matched.

7 grams per head 
5 grams per shaft(lead tape @ 14 inches form butt)
works for MOI and SW match.
WORKS!

[ARL67]

I've been recently chatting with @Noodler on MBI builds so giving this thread a bump to keep the MBI discussions going.  I've never paid attention to MBI but will really do so on my upcoming build.  My chat with him yesterday prompted me to buy some AWT 2.0 Stiff pulls, to go with a set of Mizuno 225 heads I just happened to recently get for bag #2.

 

My main set is Edel SMS Pro with SF i110cw in a 3/8" MOI build ( 37.0" 7i ) and with heavy CP2 Wrap Jumbos ( 80g )

This Edel set is populated with much heavier weights - the 7i with a Standard 50g grip is about D3.

FYI going from Jumbo to Mid is worth about 6 MBI,  and going from Jumbo to Standard is about 11 MBI.

 

Measuring yesterday, with my usual Jumbos installed, my MBI values are:

5  -  71

6  -  70

7  -  65

8  -  71

9  -  68

P  -  69

I'd say my 7i is my favourite club, which we see is the lowest MBI at 65, though I hit my 8-9-P fine.

I hit my 6i much better than by 5i, so I just switched out the grip on the 5i for a Mid and it now has MBI 64, close to my favourite 7i.

 

I've often felt over the years that my problem with longer irons ( specifically 4i & 5i ) was merely shaft length and swing-weight, but then started tuning into perhaps it is total weight, but then now MBI explains even more about the ratios of head-weight vs shaft/grip weight.

 

 

The build for bag #2 will be new MP 225 6-PW, with 7-PW to be bent 1* weak so I have a bit more launch & spin, better gapping.

I then have a new JPX-921 HMP 6i head which is 2* stronger than the 225 6i, and I'll bend that 1* strong for gapping, and it will be my 5i.  As I build a bit shorter, I need the added head weight that a 6i head gives me over a 5i head.  I once had a set of irons with AMT Whites and didn't care for those, so curious to try out the AWT 2.0 this time around.

Edited September 8, 2024 by ARL67

[BREWMASTER95060]

16 hours ago, ARL67 said:

MBI explains even more about the ratios of head-weight vs shaft/grip weight.

🙂 Yes

[Noodler]

I plan on getting back into a discussion on MBI (especially with the use of counterbalancing to adjust club balance), but first something that I'm struggling with...

 

When we use the Speedmatch Auditor MOI machine, it's always shown with the club set on the arm with the toe down.  I noticed the other day that swinging a club with the toe down vs. the toe up definitely changes the heft of the swing that you feel.  When the toe is up, you can feel that the MOI is higher.  I then verified this on my machine.  Put the club in toe up vs. toe down and you will get very different MOI readings (over 50 points on some clubs).  So I have to ask, why is it that the videos and instructions tell you to put the club on the machine toe down?  I really think that if you're trying to measure the MOI of the club, it should be oriented the same way it is when we swing it.

[ARL67]

There was a thread about the Auditor very recently on toe up vs toe down, and different readings.  Either way, you’d build the club to your liking and choose which way to measure.  I prefer toe down as less chance for accidental movement as the arm swings .

[Noodler]

21 minutes ago, ARL67 said:

There was a thread about the Auditor very recently on toe up vs toe down, and different readings.  Either way, you’d build the club to your liking and choose which way to measure.  I prefer toe down as less chance for accidental movement as the arm swings .

 

Do you happen to have the link to that thread?  I'm interested in reading it.

[Cwebb]

https://forums.golfwrx.com/topic/2002869-moi-auditor-please-confirm-club-orientation-when-measuring/

 

[Stuart_G]

7 hours ago, ARL67 said:

There was a thread about the Auditor very recently on toe up vs toe down, and different readings.  Either way, you’d build the club to your liking and choose which way to measure.  I prefer toe down as less chance for accidental movement as the arm swings .

 

Yes, consistency in how you use the machine is more important than the orientation.   In theory the orientation does not change the MOI of the club.  Why the machine is sensitive to it is not something I've seen any explanation for.

[BREWMASTER95060]

19 hours ago, Noodler said:

  I noticed the other day that swinging a club with the toe down vs. the toe up definitely changes the heft of the swing that you feel.  When the toe is up, you can feel that the MOI is higher. 

 

BP
CG
CM
Isn't always where you think it is.
 

 

 

 

[BREWMASTER95060]

On 7/2/2020 at 7:52 AM, Noodler said:

Most golfers will swear that the higher MOI clubs weigh more when they're swinging them. This all gets back to the weight distribution across the components. Even if a club weighs less than another, if more of the available weight is positioned at the head end of the club, it's going to feel heavier when swung than a club with more of the weight in the shaft.

YES

[BREWMASTER95060]

On 9/8/2024 at 6:34 AM, ARL67 said:

my usual Jumbos installed

🙂

[BREWMASTER95060]

On 9/10/2024 at 7:34 PM, Noodler said:

the Auditor very recently on toe up vs toe down, and different readings.