First time MOI build

[rebby]

I decided a few weeks ago that I really want to try an MOI build. Being that this is the first set that I'll have that is MOI matched, I don't really want to take the $500+ plunge for the MOI machine. Instead, I'm attempting a "poor man's" MOI match via some simple mathematics.

 

A couple of days ago I built myself a 7-iron that swingweighted out at just over D1. I took this club to the range today and hit about 100 balls while adding and removing lead tape. Using impact tape, I determined that my best impact patters came at roughly D4.25 (although, the pattern at D1 was pretty impressive as well, the club felt WAY to light though).

 

Based on my results, I created a quick spreadsheet to help me calculate exactly how I should build the rest of my clubs. Tonight I shafted up a 3, 5, and 9 iron and plan on repeating the above impact/lead tape test with these clubs as well. I'm hoping that I'll come out with results that are somewhat consistent with what my spreadsheet indicates.

 

Anyway, for a "poor man's" MOI match, am I going about this correctly or is there something in my process that I should change? Do my calculations in the spreadsheet look correct? I'll admit that they're probably too exacting, I can't help it, I'm an Engineer/Architect by day. ;)

 

The spreadsheet includes 2 tabs. The first will calculate the "correct" tip weight to match MOI once the bold/red fields are all populated. The second tab is basically for future reference, it's a detailed build spec of the irons that I'm working on at the moment.

 

Thanks!!!

[MrFlapjack]

Its been a while but I think its 0.6 SW points per half inch if you use a SW scale instead of an MOI machine. I have an MOI auditor, and from what I have measured it get's you pretty close.

[Cwebb]

The simple starting point is using 8g head weight increments for every half inch in length change. 4g per quarter inch change. Traditonal swing weight uses 7g per half inch

 

This will give you a nice slight progressive swing weight. You don't need to worry about a perfect MOI match all the way through when starting....and you could also experiment with some extra weight added to heads (lead tape), after your build. Many players don't benifit from a perfect MOI match all the way through, so don't assume that you will. Leave it open to a "semi blind" test

[rebby]

Its been a while but I think its 0.6 SW points per half inch if you use a SW scale instead of an MOI machine. I have an MOI auditor, and from what I have measured it get's you pretty close.

 

Sounds pretty close to what I've read as well. 2/3 SW point per 1/2" or 1/2 SW point per 3/8". In my case I want to build on 1/2" increments and avoid the inaccuracies (and/or tolerance stacking) of dealing with a SW, hence the manual calculations that I'm performing on a club by club basis.

 

If this works out as well as I'm hoping, I'll buy one of those machines for sure.

[rebby]

The simple starting point is using 8g head weight increments for every half inch in length change. 4g per quarter inch change. Traditonal swing weight uses 7g per half inch

 

This will give you a nice slight progressive swing weight. You don't need to worry about a perfect MOI match all the way through when starting....and you could also experiment with some extra weight added to heads (lead tape), after your build. Many players don't benifit from a perfect MOI match all the way through, so don't assume that you will. Leave it open to a "semi blind" test

 

That's actually the process that I'm using at the moment. After a bit of testing, once I settle on comfortable weights, I'll pull the tape and put some tungsten down the shaft.

 

I must admit though, the look of a baby blade w/lead tape on the back is kind-of sexy. All that you can see from the back is a healthy muscle pad and "FORGED". Kinda makes the onlooker wonder what's hiding under there. Then again, the majority of people who look at my irons think that they come from WalMart. LOL

[Cwebb]

Some of finest ball strikers ever, used lead tape all over their clubs. It's a useful method and makes a club look like an industrial battle weapon. Some might even find that "sexy". LOL

[rebby]

Some of finest ball strikers ever, used lead tape all over their clubs. It's a useful method and makes a club look like an industrial battle weapon. Some might even find that "sexy". LOL

 

I have to admit, I'm tempted to leave them this way.

 

My initial question still stands though, am I on the right track for an MOI build here??? ;)

[teamacacia]

My initial question still stands though, am I on the right track for an MOI build here??? ;)

 

Yes, I believe you should be. I did the same thing as you last year, and it took me from unhappy with my irons to absolutely pleased with my irons. I emailed back and forth with Tom Wishon as there is no one within a 5 hour drive that builds MOI clubs (per his website and my phone calls/emails). In the end, he recommended doing the 1/2 SW increase per club as you go down the irons. I think my 4i has 1" tape, 5i 2", and so on. I have considered purchasing a MOI machine in the future but the lead tape test works pretty well.

 

Is the 6i your longest iron in the bag? I started with my 4i and worked straight down the bag since the 4i is my longest iron. It is certainly eye opening to watch how impact spots incrementally zero in on the sweet spot as you find the perfect weight.

[Howard_Jones]

I decided a few weeks ago that I really want to try an MOI build. Being that this is the first set that I'll have that is MOI matched, I don't really want to take the $500+ plunge for the MOI machine. Instead, I'm attempting a "poor man's" MOI match via some simple mathematics.

 

A couple of days ago I built myself a 7-iron that swingweighted out at just over D1. I took this club to the range today and hit about 100 balls while adding and removing lead tape. Using impact tape, I determined that my best impact patters came at roughly D4.25 (although, the pattern at D1 was pretty impressive as well, the club felt WAY to light though).

 

Based on my results, I created a quick spreadsheet to help me calculate exactly how I should build the rest of my clubs. Tonight I shafted up a 3, 5, and 9 iron and plan on repeating the above impact/lead tape test with these clubs as well. I'm hoping that I'll come out with results that are somewhat consistent with what my spreadsheet indicates.

 

Anyway, for a "poor man's" MOI match, am I going about this correctly or is there something in my process that I should change? Do my calculations in the spreadsheet look correct? I'll admit that they're probably too exacting, I can't help it, I'm an Engineer/Architect by day. ;)

 

The spreadsheet includes 2 tabs. The first will calculate the "correct" tip weight to match MOI once the bold/red fields are all populated. The second tab is basically for future reference, it's a detailed build spec of the irons that I'm working on at the moment.

 

Thanks!!!

 

im not sure if you have weighted up all components? both tape and ferrule seems a bit heavy, and the MOI return number seems to be way to high, but i did not look over your formulas.

 

Do you have a SW scale since you say your #7 was good at D4.25?

Is that your start iron, the one you wants to duplicate to the others?

[rebby]

im not sure if you have weighted up all components? both tape and ferrule seems a bit heavy, and the MOI return number seems to be way to high, but i did not look over your formulas.

 

Do you have a SW scale since you say your #7 was good at D4.25?

Is that your start iron, the one you wants to duplicate to the others?

 

First of all, thanks for chiming in here Howard. Your's is one of the names that I was hoping to see when I first posted this topic.

 

I did weigh everything with the exception of the tape. I found a source online that said 12" of double sided tape was roughly 4g so that's what I used. It seems a little high to me but, based on the equation, total grip weight doesn't factor into it a whole lot. Since all of my clubs match in this regard however, I'm not sure if the exact measurement is critical? The ferrule weight is accurate, it's high because I'm using 1"+ classic-style ferrules. They are all weighing in between 1.9 and 2.0g.

 

The equation that I'm using is as follows;

 

MOI = (L^2*(H + S/3) + 10*G) / 100

 

Where:

 

MOI = The moment of inertia of the club

L = Club Length (inches)

H = Head weight (grams) + Ferrule weight (grams) + Tip weight (grams)

S = Trimmed Shaft weight (grams)

G = Grip weight (grams) + Grip tape weight (grams)

 

I found the basis for this equation here -> http://www.tutelman.com/golf/design/swingwt2.php With the initial equation, I actually get numbers in the 430,000-range so I divided this by 100 to get something more inline with MOI numbers that I've seen elsewhere. The more that I look into it though, I'm not sure that this is a correct divisor (perhaps it's a totally incorrect equation)? It does seem close though, if I look at just my 7-iron and my 3-iron, here are my "results" (bear in mind, my SW scale is not digital, full/half SWs are pretty obvious but anything in-between is a bit of guessing game. This is primarily why I'm trying to do this based on an equation rather than using swing weight).

 

7-iron: "Natural" swing weight was about D1, maybe D1.25. I added just a touch under 6g and ended up with a swing weight in the D4.25 range (according to my scale, it's just a sliver higher than D4).

3-iron: Using the 2/3 SW pt per half-inch means that my 3-iron should come in at about 1.4 (based on a D4 7-iron). The "natural" swing weight was, like the 7-iron, roughly a sliver higher than D1. Calculations from the spreadsheet tell me that I should add 0.8g to MOI match the 7-iron which, using the 2g/SW pt, looks perfect.

 

Yes, I did start with the 7-iron. No good reason to do so other than picking my "favorite club" and working from there. I did not start with a "finished" 7-iron though, I built it with no tip weights and added/removed lead tape to find my best impact pattern. Interestingly enough, the final swing weight of the 7-iron came in pretty close to what I likely would have built it at from the start. While I was at the range, I proceeded to add a little weight to a few of my shorter clubs (from another set) and saw improvements in my impact patters there as well (apples/oranges though, different shafts, different head weights, etc). Now that I have a few more clubs built, I'll repeat the test to see if the numbers match up (3, 5, & 9-irons).

 

FWIW, I'm building the set as a 2-PW, 52, 57, and 62. Dialing in the 7-iron was pretty easy so I may just use that process for every club using the numbers that I get on the spreadsheet as a suggestion more than anything else. It would be nice if the MOI matched perfectly, mathematically, but in the end what I'm really aiming for here is impact consistency and results so maybe the math doest matter (gasp).

[Howard_Jones]

im not sure if you have weighted up all components? both tape and ferrule seems a bit heavy, and the MOI return number seems to be way to high, but i did not look over your formulas.

 

Do you have a SW scale since you say your #7 was good at D4.25?

Is that your start iron, the one you wants to duplicate to the others?

 

First of all, thanks for chiming in here Howard. Your's is one of the names that I was hoping to see when I first posted this topic.

 

I did weigh everything with the exception of the tape. I found a source online that said 12" of double sided tape was roughly 4g so that's what I used. It seems a little high to me but, based on the equation, total grip weight doesn't factor into it a whole lot. Since all of my clubs match in this regard however, I'm not sure if the exact measurement is critical? The ferrule weight is accurate, it's high because I'm using 1"+ classic-style ferrules. They are all weighing in between 1.9 and 2.0g.

 

The equation that I'm using is as follows;

 

MOI = (L^2*(H + S/3) + 10*G) / 100

 

Where:

 

MOI = The moment of inertia of the club

L = Club Length (inches)

H = Head weight (grams) + Ferrule weight (grams) + Tip weight (grams)

S = Trimmed Shaft weight (grams)

G = Grip weight (grams) + Grip tape weight (grams)

 

I found the basis for this equation here -> http://www.tutelman....gn/swingwt2.php With the initial equation, I actually get numbers in the 430,000-range so I divided this by 100 to get something more inline with MOI numbers that I've seen elsewhere. The more that I look into it though, I'm not sure that this is a correct divisor (perhaps it's a totally incorrect equation)? It does seem close though, if I look at just my 7-iron and my 3-iron, here are my "results" (bear in mind, my SW scale is not digital, full/half SWs are pretty obvious but anything in-between is a bit of guessing game. This is primarily why I'm trying to do this based on an equation rather than using swing weight).

 

7-iron: "Natural" swing weight was about D1, maybe D1.25. I added just a touch under 6g and ended up with a swing weight in the D4.25 range (according to my scale, it's just a sliver higher than D4).

3-iron: Using the 2/3 SW pt per half-inch means that my 3-iron should come in at about 1.4 (based on a D4 7-iron). The "natural" swing weight was, like the 7-iron, roughly a sliver higher than D1. Calculations from the spreadsheet tell me that I should add 0.8g to MOI match the 7-iron which, using the 2g/SW pt, looks perfect.

 

Yes, I did start with the 7-iron. No good reason to do so other than picking my "favorite club" and working from there. I did not start with a "finished" 7-iron though, I built it with no tip weights and added/removed lead tape to find my best impact pattern. Interestingly enough, the final swing weight of the 7-iron came in pretty close to what I likely would have built it at from the start. While I was at the range, I proceeded to add a little weight to a few of my shorter clubs (from another set) and saw improvements in my impact patters there as well (apples/oranges though, different shafts, different head weights, etc). Now that I have a few more clubs built, I'll repeat the test to see if the numbers match up (3, 5, & 9-irons).

 

FWIW, I'm building the set as a 2-PW, 52, 57, and 62. Dialing in the 7-iron was pretty easy so I may just use that process for every club using the numbers that I get on the spreadsheet as a suggestion more than anything else. It would be nice if the MOI matched perfectly, mathematically, but in the end what I'm really aiming for here is impact consistency and results so maybe the math doest matter (gasp).

 

im not on my regular computer, and formulas like that is not something i remember in my head, but we need the balance point of the object, not only its lenght and weight, so if you have a SW scale, use it, its not a bad instrument when you know its limitations and you seems to know already that we have to use a progressive slope vs club length with 2/3 or 0.66 SWP for each 4/8" of club lenght, and at 3/8" its 0.5 SWP and at 2/8 its 1/3 SWP, so just do it using your SW scale.

 

SW points to gram is not a constant of 2 grams, but 2 is the average for irons

 

http://www.golfwrx.com/forums/topic/44071-swing-weight-factors-in-relation-to-parts/page__st__240__p__10867357#entry10867357

[rebby]

im not on my regular computer, and formulas like that is not something i remember in my head, but we need the balance point of the object, not only its lenght and weight, so if you have a SW scale, use it, its not a bad instrument when you know its limitations and you seems to know already that we have to use a progressive slope vs club length with 2/3 or 0.66 SWP for each 4/8" of club lenght, and at 3/8" its 0.5 SWP and at 2/8 its 1/3 SWP, so just do it using your SW scale.

 

SW points to gram is not a constant of 2 grams, but 2 is the average for irons

 

http://www.golfwrx.c...7#entry10867357

 

It sounds like I'm on the right track, overthinking it like usual, but on the right track.

 

The formula that I'm using does not take into account the balance point, I did find that a little odd. My assumption is that the calculation is based on a specific shaft balance point that may be "accurate enough". I can't say for sure though. I will say this, I certainly have an immense respect for the MOI machine that is available on the market and completely understand why the price point is where it is. It's certainly a precision instrument (fractions of a gram matter!) and it's normalizing a great deal of a variables into a single consumable value, that's impressive.

 

My primary reasoning for attempting to build this per calculations rather than simply doing a progressive swing weight are the limitations of my equipment. I know that the scale that I own is not capable of making the measurements as precise as I'd like it to be in order to follow a 0.66pt/0.5" slope. Therefore, I'm hoping that by doing the math, I can get closer to the the actual numbers. If this personal experiment works out and I decide to base my future builds on MOI, I'll buy the proper equipment. If not and I decide to stick with constant SW builds, I'll get a better SW scale.

 

I did realize that SW/gram was not a constant at 2 which is why I used my 3-iron in my above example instead of my 5-iron or 9-iron (for my 3-iron @ 39", 2g is correct). The post that you're linking to appears to be similar to what I have in my build notes;

 

length - Grams pr. SW point

45.0 - 1,59

44.5 - 1,62

44.0 - 1,65

43.5 - 1,68

43.0 - 1,71

42.5 - 1,74

42.0 - 1,77

41.5 - 1,8

41.0 - 1,84

40.5 - 1,88

40.0 - 1,92

39.5 - 1,96

39.0 - 2

38.5 - 2,04

38.0 - 2,08

37.5 - 2,12

37.0 - 2,16

36.5 - 2,21

36.0 - 2,26

35.5 - 2,31

35.0 - 2,36

34.5 - 2,41

 

In all honesty, I believe that information came directly from you (the comma being used to denote the decimal tips me toward a 99.999% certainty).

 

I can see why the "average" club builder doesn't focus on MOI based builds. They're more time consuming, more exacting, more work. With the vast majority of people not even being able to ascertain a difference in swing weight, I can see how being so meticulous could be viewed as "wasted time" by somebody trying to turn a profit based on volume. Also, I can understand why OEMs haven't gone in this direction either with everybody having their "own" MOI. Although, I am beginning to wonder why a progressive SW of something arbitrary like 0.5pt/0.5" hasn't become a little more common...

[Howard_Jones]

Yes, that quote might be from me, we use comma as separator in Europe, and i rebuild my own set to progressive SW before i got any Club making equipment like SW scale or anything, so if you dont trust the instrument, but trust your self using a ruler and a gram scale, then use this method.

 

The play ready club is placed over one finger to find the approximate balance point of the club.

Take a piece of painter tape around the shaft at that point.

Now "fine tune the balance" on the edge of a knife, and when the club is in perfect balance, push it down against the knife to make a mark in the painters tape. Now measure the length from the top end of the grip and down to the Balance point, use millimeters if possible. Then put the hole club on a gram scale, and go to this web page where you can enter weight in grams and distance to BP, and the page return a SW value. its just as good as any SW scale, and if you measure without grips on (dry fit), just SUB 9 SWP from the return value.

 

http://www.leaderboard.com/swingwt.htm