MOI Matching - Short Length

[dlow206]

@Howard_Jones - i am confusing myself a bit with the calculator. Here are the values i have captured so far as input parameters. I think i might be confusing myself because i am looking at swingweight input information in the spreadsheet and i think the spreadsheet assumes that the lowest swingweight is D0. My 8 iron will swingweight around C9, maybe D0 assuming a 50 gram grip. 

 

[Howard_Jones]

6 minutes ago, dlow206 said:

@Howard_Jones - i am confusing myself a bit with the calculator. Here are the values i have captured so far as input parameters. I think i might be confusing myself because i am looking at swingweight input information in the spreadsheet and i think the spreadsheet assumes that the lowest swingweight is D0. My 8 iron will swingweight around C9, maybe D0 assuming a 50 gram grip. 

 

Just IGNORE the letter D in the black field, its PHOTO of that letter only.
If start SW is D9, you simply use MINUS 1.0 since D0 is the lowest positive value

[dlow206]

Ok, so i measured the swingweight right now of the shaft and head (dry fitted) with no grip and no ferrule and no epoxy. The swingweight without these comes out to D6, so probably around C6 or C7 in the 8 iron built? I took all of the info i have collected and have come up with.

 

@Howard_Jones - what i care most about is the right amount of grams to add to the build based on my finding that approximately +3.3 grams was the optimized weight for my 8 iron. Also, not sure what is happening with the GW and SW, but im not planning to remove any weight from those clubs. Does the below look correct?

 

[Howard_Jones]

D6 W/O grip is the same as C7 with a standard grip, but i found a programming error ive made, so to get correct values, we have to use 6.40 as start SW value, and then the SW tuner and add 0.60 so head weight for the #8 becomes 0 (as adjustment.



IF you need DRY FIT  SW values W/O grips, use 5.4 start and add 0.60 with the SW tuner to get D6 w/o gripped (need for head weight remains un-changed, only SW numbers change so we dont have to look at another value on the screen than on the SW scale.)

 
 

[dlow206]

3 minutes ago, Howard_Jones said:

D6 W/O grip is the same as C7 with a standard grip, but i found a programming error ive made, so to get correct values, we have to use 6.40 as start SW value, and then the SW tuner and add 0.60 so head weight for the #8 becomes 0 (as adjustment.



IF you need DRY FIT  SW values W/O grips, use 5.4 start and add 0.60 with the SW tuner to get D6 w/o gripped (need for head weight remains un-changed, only SW numbers change so we dont have to look at another value on the screen than on the SW scale.)

 
 

 

Thank you so much for the detailed help with all of this, really appreciate it @Howard_Jones

[Howard_Jones]

4 minutes ago, dlow206 said:

 

Thank you so much for the detailed help with all of this, really appreciate it @Howard_Jones

You and everyone else is welcome as long as we do this in the forum so other readers can follow the project and learn how to do this.

PS i DID NOT enter YOUR actual head wgt numbers for any other clubs than the 8, so dont get confused by the weight need on my photos in the last reply.

[dlow206]

@Howard_Jones- I believe I have the spreadsheet setup correctly for dryfitting based on all of your prior posts. My remaining question is around the wedges, seems like a big jump in grams to add for the the GW and SW. Any changes I can do specifically for the wedges so i don't have to add so much weight to the wedges?

 

[Howard_Jones]

If you look at "expected head wgt", you will see the issue. (1 line above actual)
Playing all wedges to the same PL as your PW can be done, but when you adjust for that, you can see it want help much since we are above 2.3 grams for each SWP

A tip weight, and lead tape combined is really your only option.

PS! there is BRASS FERRULES out there to gain weight a when tip weight alone cant do it.
I never used them myself.
https://www.ebay.com/itm/282215411778?hash=item41b5597042:g:IMMAAOSwmfhX7UTq

[dlow206]

7 hours ago, Howard_Jones said:

If you look at "expected head wgt", you will see the issue. (1 line above actual)
Playing all wedges to the same PL as your PW can be done, but when you adjust for that, you can see it want help much since we are above 2.3 grams for each SWP

A tip weight, and lead tape combined is really your only option.

PS! there is BRASS FERRULES out there to gain weight a when tip weight alone cant do it.
I never used them myself.
https://www.ebay.com/itm/282215411778?hash=item41b5597042:g:IMMAAOSwmfhX7UTq

Thanks Howard. I put together the table below that takes the target head weights from the spreadsheets and checks the difference in weight between subsequent clubs. My brain is a little slow today, but why such a big jump in the Target weight between PW and GW?

 

[Howard_Jones]

39 minutes ago, dlow206 said:

Thanks Howard. I put together the table below that takes the target head weights from the spreadsheets and checks the difference in weight between subsequent clubs. My brain is a little slow today, but why such a big jump in the Target weight between PW and GW?

 

Good question...its years since i made that calculator, so i would have to look into the background parameters to see how that number is calculated.

7.7 grams from #9 to PW, and 11.8 up to GW dont sound right for me either...

ill look into that...
 

[ARL67]

Howards math, charts, and advice in this post are second to none.   For your first few builds, it is good to know about all the parameters and consequences of yours choices, and what is readily buildable without too much fuss.  And as Howard always points out, we first go by feel, doing trial and error with lead tape, shaft length experimentation, etc.  Then we measure what we like, and use that as our reference to build further clubs in our set.

 

At some point in your building "career" you will filter down and know what works for you, and building gets simpler just by trusting your former experiences.   You just build your base club, and merely build to 1.33 SWP per inch.  Your SW scale and a sander / grinder ( to grind down your tip weights to perfection ) will make the build go fast, and no math required. 

 

Whatever base club you decide on  ( in your case a 9i I believe ), I suggest to also build the 6i and evaluate those 2 clubs before going further, whether in a Sim or at the range.  I find I can handle much heavier SW in shorter irons than I can with longer irons.  If I err too heavy on my 9i, that SW progression might not translate up nicely to 6-5-4 irons.  This is especially true if your next build is a completely different set of heads and shafts -> no previous experience with that pairing, so start from scratch with SW testing.

 

FYI:

I know from my own experience,  I Iike Steelfiber i95cw Regulars, with my ungripped 9i at 36.0" and a dry SW of e2.0 with shaft + ferrule + tip weights + head.  I know the SW affects of my epoxy, tape, and the grip I use.  I build Single-Length 9-P-G-S-L to 36.0" .  Then I go up in either 1/4" increments using the 1.33 SWP per inch formula.   I used to go 3/8" , and currently trying to do 1/8" , but need my arsenal of Wishon tungsten tip weights and heavy ferrules ( check BigFootGolf on the 'Bay for his heavy stainless steel, brass, and copper ferrules that weight 13,14,15g respectively ).  If using steel shafts, you can buy 16g lead weights from 'Bay sellers in China.   If you like really short increments, you need a tip heavier shaft ( low balance point ) to make such builds possible.  I like the feel of Steelfibers and the i95cw Regulars have the lowest balance point to allow me to build super short, whereas the i110cw are high balance point and just not possible to build to the short lengths I want.

Edited November 1, 2021 by ARL67

[Howard_Jones]

WOW...i found where its "happening", but since its years since i made this, i have a hard time wrapping my head around some "correction" numbers. Im simply not able to give you a answer or fix a possible error today, it will take me hours to go over it all. (its tons of calculations running in the back ground hidden both below and above the visible screen and they are all involved....

[dlow206]

14 minutes ago, Howard_Jones said:

WOW...i found where its "happening", but since its years since i made this, i have a hard time wrapping my head around some "correction" numbers. Im simply not able to give you a answer or fix a possible error today, it will take me hours to go over it all. (its tons of calculations running in the back ground hidden both below and above the visible screen and they are all involved....

 

Thanks for going through this. Is the issue only impacting the wedge numbers or the other irons as well?

[Howard_Jones]

1 hour ago, dlow206 said:

 

Thanks for going through this. Is the issue only impacting the wedge numbers or the other irons as well?

Not likely, since the numbers is all "relative", so all it really does is to calculate drop in SWP when shortening, then it calculate how many grams needed to get to target relative to the new play length.

I need a "clear head" to look it all over, but it seems like it belongs to FLEX changes (the numbers for compensation who might have made this error), but ive been using a version no 3 myself, and will have to see if there is differences to version 2 i made public, so i will look into that tomorrow, i had half a bottle of red wine to the dinner, so the head is not prepared for a task like that now. 

[dlow206]

13 minutes ago, Howard_Jones said:

Not likely, since the numbers is all "relative", so all it really does is to calculate drop in SWP when shortening, then it calculate how many grams needed to get to target relative to the new play length.

I need a "clear head" to look it all over, but it seems like it belongs to FLEX changes (the numbers for compensation who might have made this error), but ive been using a version no 3 myself, and will have to see if there is differences to version 2 i made public, so i will look into that tomorrow, i had half a bottle of red wine to the dinner, so the head is not prepared for a task like that now. 

 

No hurry to update the spreadsheet. I also just ordered an Auditor/Golf Mechanix MOI Matching machine. I am really interested in MOI matching and figure i will own many different sets in the future and will also use it for other club building endeavors. I will check how the measurements match up against the spreadsheet.  

[Flacoman]

On 10/28/2021 at 5:45 PM, Flacoman said:

You can also slit the end of the shaft for a fit. Callaway did that for a while.

Correct , my bad.

[dlow206]

My machine is here. didn't get too far yet, finished the calibration and testing some MOI measurements using my reference 8 iron

 

[dlow206]

So using 3/8" between each iron from 5 to 9 and the 1/4" from 9, PW, GW and then keeping GW and SW the same length, the MOI measured values using the MOI speed machine were much closer to the optimized 8 iron than I would have expected based on the spreadsheet calculations. A few heads needed a small amount of weight added, but none more than  a few grams. I also measured each club many times on the MOI machine to make sure there wasn't any error in reading. There is some variation in readings, but well within an acceptable tolerance. 

 

Also, when I did the measurements, I already had the ferrules installed and then used a piece of tape to both hold the head securely in place and also roughly approximate the weight of the epoxy. 

 

This has been a really awesome learning experience. Thanks again to @Howard_Jones for your contribution not just on this thread but all you do for the Golf WRX community. 

[Howard_Jones]

1 hour ago, dlow206 said:

So using 3/8" between each iron from 5 to 9 and the 1/4" from 9, PW, GW and then keeping GW and SW the same length, the MOI measured values using the MOI speed machine were much closer to the optimized 8 iron than I would have expected based on the spreadsheet calculations. A few heads needed a small amount of weight added, but none more than  a few grams. I also measured each club many times on the MOI machine to make sure there wasn't any error in reading. There is some variation in readings, but well within an acceptable tolerance. 

 

Also, when I did the measurements, I already had the ferrules installed and then used a piece of tape to both hold the head securely in place and also roughly approximate the weight of the epoxy. 

 

This has been a really awesome learning experience. Thanks again to @Howard_Jones for your contribution not just on this thread but all you do for the Golf WRX community. 

Please post the correction needed vs the spreadsheet. It was made after i sold my shop, so i never got to try it up against the MOI machine i had.

Tolerances is "personal" but i used plus minus 5 MOI points from target as good enough. if target was 2650, 2645 to 2655 become the range.

A input for you about grips
I prefer to mach everything without grips, so we dont tune head wgt due to grips that can be plus minus 3.5 grams. On a MOI machine that want matter (see below), but for Total weight progression club to club it does, and dont forget that Total weight is more important than SW or MOI.

Thats why i suggest that we mach everything without grips, then we weight sort our grips and distribute them so we get total weight progression from club to club as linear as possible.

Here is some numbers i did using both the MOI scale and the SW scale to see how the numbers moved depending on what grip we added. (should have used a longer shaft, but the differences remains the same).





 

Edited November 4, 2021 by Howard_Jones

[Howard_Jones]

A tip for dry fitting using the MOI scale.

Get 2 rolls of fishing line, i used 0.35 mm and 0.50 mm
Make a "loop" you put to the bottom of the hosel, and insert the shaft.
Depending on hosel spill, 0.35 mm or 0.50 mm will be enough to fix the head temporary to the shaft, and good enough for use when Flex/CPM matching was done, so its more than good enough for the MOI machine where the club moves way slower.

ALWAYS check LENGTH on the ruler so you know for sure that the shaft is fully inserted before you place the club on the MOI scale.

[dlow206]

14 hours ago, Howard_Jones said:

Please post the correction needed vs the spreadsheet. It was made after i sold my shop, so i never got to try it up against the MOI machine i had.

Tolerances is "personal" but i used plus minus 5 MOI points from target as good enough. if target was 2650, 2645 to 2655 become the range.

A input for you about grips
I prefer to mach everything without grips, so we dont tune head wgt due to grips that can be plus minus 3.5 grams. On a MOI machine that want matter (see below), but for Total weight progression club to club it does, and dont forget that Total weight is more important than SW or MOI.

Thats why i suggest that we mach everything without grips, then we weight sort our grips and distribute them so we get total weight progression from club to club as linear as possible.

Here is some numbers i did using both the MOI scale and the SW scale to see how the numbers moved depending on what grip we added. (should have used a longer shaft, but the differences remains the same).





 

 

Thanks Howard. One issue that i had with trying to measure on the machine without grips was the nub at the end of the machine intended to hold the shaft on for measuring ungripped was too small to fit the inner diameter of my graphite iron shafts. it would have been fine if the shafts were steel. I did use one single grip that is split open to measure on each club, so at least that it was constant.

 

Here was the original predicted weights to add:

 

 

Here is where my measurements came out to be:

 

 

[Howard_Jones]

8 hours ago, dlow206 said:

 

Thanks Howard. One issue that i had with trying to measure on the machine without grips was the nub at the end of the machine intended to hold the shaft on for measuring ungripped was too small to fit the inner diameter of my graphite iron shafts. it would have been fine if the shafts were steel. I did use one single grip that is split open to measure on each club, so at least that it was constant.

 

Here was the original predicted weights to add:

 

 

Here is where my measurements came out to be:

 

 

i did not see that one coming...

It say that the spread sheet mis target by about 0.5 SWP all the way, and for the #7 a FULL SWP
since 1 SWP is 2.16 grams at that length. i cant wrap my head around how thats possible 

We go 1/8" shorter only from the #8, thats loosing 0.75 SWP, but since we want a drop from D2 to D1.5 (or about 0.5 SWP), all we have to replace should be 0.25 SWP x 2.16 grams and thats 0.54 grams, but the MOI scale wants another 2.26 grams to get to target?

i simply dont get it, but the calculator is useless if it miss target by that much, and i cant imagine that your lie angles or length measurements is that much off. (the club head has to be about 4-5 more upright than it should be to reduce MOI and SW that much vs the expected for the actual head weight.

Check set up and calibration again, just to make sure, since the numbers we see here cant be explained, and also check the length of the #7 and make sure its 3/8" shorter only vs the #8.
 

[dlow206]

6 hours ago, Howard_Jones said:

i did not see that one coming...

It say that the spread sheet mis target by about 0.5 SWP all the way, and for the #7 a FULL SWP
since 1 SWP is 2.16 grams at that length. i cant wrap my head around how thats possible 

We go 1/8" shorter only from the #8, thats loosing 0.75 SWP, but since we want a drop from D2 to D1.5 (or about 0.5 SWP), all we have to replace should be 0.25 SWP x 2.16 grams and thats 0.54 grams, but the MOI scale wants another 2.26 grams to get to target?

i simply dont get it, but the calculator is useless if it miss target by that much, and i cant imagine that your lie angles or length measurements is that much off. (the club head has to be about 4-5 more upright than it should be to reduce MOI and SW that much vs the expected for the actual head weight.

Check set up and calibration again, just to make sure, since the numbers we see here cant be explained, and also check the length of the #7 and make sure its 3/8" shorter only vs the #8.
 

 

Thanks Howard, I don't get it either. I checked the calibration many times, and to me, it appears to be reading correctly (using the calibration stick provided with the unit). 

 

I don't have a digital swingweight scale, but use my cheap analog swingweight scale, i double checked and the clubs are increasing in swingweight properly, thought it would be better if i had a digital swingweight scale to be able to be more precise.

 

I am going to do some more investigation and checking today. Does shaft weight matter in the MOI measurement? Wondering if that is impacting the model, because these are lightweight graphite iron shafts. 

[Howard_Jones]

40 minutes ago, dlow206 said:

 

Thanks Howard, I don't get it either. I checked the calibration many times, and to me, it appears to be reading correctly (using the calibration stick provided with the unit). 

 

I don't have a digital swingweight scale, but use my cheap analog swingweight scale, i double checked and the clubs are increasing in swingweight properly, thought it would be better if i had a digital swingweight scale to be able to be more precise.

 

I am going to do some more investigation and checking today. Does shaft weight matter in the MOI measurement? Wondering if that is impacting the model, because these are lightweight graphite iron shafts. 

Yes shaft weight is part of it, just like its part of SW, but even if those shafts is descending weight, that cant explain the numbers, especially NOT for the #7

If you dont trust your SW scale, its easy to check SW without.

Hold the club on one finger to find the approximate balance point, and put a piece of painters tape on the shaft at that area. Now take a knife with the blade UP and fix it in a vise.

Put the club on the knife edge, and adjust back and forward until you find the exact balance point.

Push the club down against the knife to set a mark in the painters tape (Not the shaft, thats why we added the tape).

Put the club with the grip in against a wall, do the same with a ruler and measure distance from the end of the grip (or shaft butt) to the BP in Centimetres. (take notes)

Put the club on a gram scale and take notes.

Enter those numbers in the "stand alone" SW calculator in the spread sheet.
Its below target for head wgt.

 

Edited November 5, 2021 by Howard_Jones

[dlow206]

9 minutes ago, Howard_Jones said:

Yes shaft weight is part of it, just like its part of SW, but even if those shafts is descending weight, that cant explain the numbers, especially NOT for the #7

If you dont trust your SW scale, its easy to check SW without.

Hold the club on one finger to find the approximate balance point, and put a piece of painters tape on the shaft at that area. Now take a knife with the blade UP and fix it in a vise.

Put the club on the knife edge, and adjust back and forward until you find the exact balance point.

Push the club down against the knife to set a mark in the painters tape (Not the shaft, thats why we added the tape).

Put the club with the grip in against a wall, do the same with a ruler and measure distance from the end of the grip (or shaft butt) to the BP in Centimetres. (take notes)

Put the club on a gram scale and take notes.

Enter those numbers in the "stand alone" SW calculator in the spread sheet.
Its below target for head wgt.

 

 

@Howard_Jones - i was trying to think about other factors that may have an impact on the measurements, aside from the measured lengths and headweights, and in particular, why such a big difference in the predicted weight needed to be added to the 7 iron vs. what the MOI machine read. so there is one factor that i did not think about and i am not sure what impact it would have, if any. 

 

my iron set, the long/mid irons (5 to 7), Titleist put an additional weight that is sort of toe side in the T300 model to make them easier to launch (these are GI, borderline SGI irons)

 

.

 

From 8 iron onwards, there isn't that weight (below is my 8 iron)

 

 

[Howard_Jones]

If the heads is still loose, you can measure COG quite simple.

Take a pen of the type where you push a button on the top to get the tip out.
Find some paint.
Dip the pen tip itself in that paint.
Push the button so the tip hides behind the cover
Put the pen in a vise tip up as strait as you can
Place the club head face down on the pen tip and move it around until you find the spot where the head can rest on the pen tip without your support
Hold the head in that position with one hand, push the pen button with the other to set a mark on the club face.

Do that with #7 and #8 and compare them

A Good designed set of irons has a slight progression UP for COG as loft goes up, to compensate for loft, since loft brings it down, and thats means the #7 shall have a slightly LOWER COG than the #8, but our numbers here indicates the opposite if that was the issue, and it takes "a lot" to move SW or MOI that much as we see on your numbers.

You can also try to add lets say 10 grams of lead tape on the sole, measure MOI
Move that 10 grams to the hosel and measure again
you will see that its not much we can change the numbers, and COG will be about 0.14 to 0.17 mm as progression from head to head, (0.14 equalize 4* of loft) and thats so little, we have issues to measure it, unless we compare a #3 iron to a #9.

Edited November 5, 2021 by Howard_Jones

[dlow206]

51 minutes ago, Howard_Jones said:

If the heads is still loose, you can measure COG quite simple.

Take a pen of the type where you push a button on the top to get the tip out.
Find some paint.
Dip the pen tip itself in that paint.
Push the button so the tip hides behind the cover
Put the pen in a vise tip up as strait as you can
Place the club head face down on the pen tip and move it around until you find the spot where the head can rest on the pen tip without your support
Hold the head in that position with one hand, push the pen button with the other to set a mark on the club face.

Do that with #7 and #8 and compare them

A Good designed set of irons has a slight progression UP for COG as loft goes up, to compensate for loft, since loft brings it down, and thats means the #7 shall have a slightly LOWER COG than the #8, but our numbers here indicates the opposite if that was the issue, and it takes "a lot" to move SW or MOI that much as we see on your numbers.

You can also try to add lets say 10 grams of lead tape on the sole, measure MOI
Move that 10 grams to the hosel and measure again
you will see that its not much we can change the numbers, and COG will be about 0.14 to 0.17 mm as progression from head to head, (0.14 equalize 4* of loft) and thats so little, we have issues to measure it, unless we compare a #3 iron to a #9.

 

Thanks, I had already built them last night. Going to try out the set as-is. But from an intellectual curiosity standpoint, going to try to figure out more what's going on with the numbers. 

 

One question @Howard_Jones, when i install grips, i think you mentioned i should weight sort them. Do I then install the lightest grip on the lightest club (i.e. 5 iron)?

[Howard_Jones]

22 minutes ago, dlow206 said:

 

Thanks, I had already built them last night. Going to try out the set as-is. But from an intellectual curiosity standpoint, going to try to figure out more what's going on with the numbers. 

 

One question @Howard_Jones, when i install grips, i think you mentioned i should weight sort them. Do I then install the lightest grip on the lightest club (i.e. 5 iron)?

Measure total wgt of all clubs w/o grips and draw a slope
Measure wgt of all grips
Use the tolerances in grip wgt to even out total weight progression as good as possible

[dlow206]

Quick update. Clubs are fully built including grips. A couple of clubs were below the 8 iron MOI measurement, so i added a small amount of lead tape, likely less than a gram or so to the few clubs that I added weight to. All irons are now pretty close in MOI measurement.

 

Still haven't figured out why the amount of weight added turned out to be a fair amount less than what was predicted by the calculator. With the MOI Speed machine, i check the level many times, calibrated it many times to make sure it was reading correctly, and i could not find any issue with the calibration. Overall, very happy with the process and many thanks to @Howard_Jones

[Howard_Jones]

4 hours ago, dlow206 said:

Quick update. Clubs are fully built including grips. A couple of clubs were below the 8 iron MOI measurement, so i added a small amount of lead tape, likely less than a gram or so to the few clubs that I added weight to. All irons are now pretty close in MOI measurement.

 

Still haven't figured out why the amount of weight added turned out to be a fair amount less than what was predicted by the calculator. With the MOI Speed machine, i check the level many times, calibrated it many times to make sure it was reading correctly, and i could not find any issue with the calibration. Overall, very happy with the process and many thanks to @Howard_Jones

Can you please post the specs from your notes with both head wgt, shaft wgt , grip wgt and total weight?

Are you saying that the numbers moved from DRY FIT on the MOI scale to built clubs?
Did you check final length after epoxy, BEFORE grips?