MOI Matched Iron Set Head Weight Progression

[CF88]

@Howard_JonesI have a quick question for a MOI iron build I'm currently working on. So far I have completed these steps

1. Heads weighed/recorded

2. Shafts cut to length and weighed/recorded

3. Built the 8 iron with no tip weight and determined the best amount of lead tape added for my swing

4. Cut off the grip and found the swing weight of the assembled club minus the grip and grip tape

5. Disassembled the 8 iron and re-weighed all pieces to determine the tip weight I need to get the desired swing weight

 

Now I'm at the point where I need to determine how much weight to add to each club in my set to get the correct swing weight slope. I will be using a swing weight scale to verify I have .5 swp increments between each club so my questions are more for my understanding of the process of MOI matching.

 

My question now is what is the correct way to approach head weight slope? I have used the search function and read every thread about MOI matching, but I can't figure out the correct way to approach this. I have read numerous times that a 7g slope with 3/8" between clubs would result in a roughly MOI matched set. Contrary to that I have also found your chart (shown below) in many MOI threads showing a progression based on a 9 iron where you add .7g to the 8 iron, 1.3g to the 7 iron, 1.9 grams to the 5 iron and remove 3.4g from the pitching wedge. Is the chart the most accurate way to go, and what formula did you use to determine the additional weight to add to each club above the 7g increments? I know you are one of the most experienced members on this forum regarding MOI matching so I want to make sure I'm following your instructions correctly and understand the underlying concepts. 

 

The set I am building is based on an 8 iron and includes 5-PW. My 8 iron head weight is 275g from the factory and I will be adding a 3g tip weight to obtain a dry swing weight of E3 with a standard DG S300 shaft. Based on a 278g head weight for the 8 iron, what would the correct head weight progression be? Thank you very much for any insight and help you can provide!

Edited September 26, 2022 by CF88

[ChaosTheory]

One small caution, and you probably know this but just to be safe since you are being meticulous.

 

Lead tape on the blade will influence swing weight more than the equal hosel weight will.

[CF88]

@Snowman9000, thank you for the heads up on that. That's something I was actually curious about too, but I hadn't read anything about the difference between the two. Would I be correct in using a swing weight scale and adding tip weight until I reach my desired E3 ungripped SW? Instead of assuming 3g of lead tape across the club head is equal to 3g hosel weight.

Edited September 26, 2022 by CF88

[Ri_Redneck]

2 hours ago, Snowman9000 said:

One small caution, and you probably know this but just to be safe since you are being meticulous.

 

Lead tape on the blade will influence swing weight more than the equal hosel weight will.

Wrapping it around the hosel will be more accurate.

 

BT

[ChaosTheory]

2 hours ago, CF88 said:

@Snowman9000, thank you for the heads up on that. That's something I was actually curious about too, but I hadn't read anything about the difference between the two. Would I be correct in using a swing weight scale and adding tip weight until I reach my desired E3 ungripped SW? Instead of assuming 3g of lead tape across the club head is equal to 3g hosel weight.

You can do that but the lack of ferrule and epoxy is about half a swing weight point.  

[CF88]

1 hour ago, Snowman9000 said:

You can do that but the lack of ferrule and epoxy is about half a swing weight point.  

Sorry, I should have specified that I will be dry swing weighting with the ferrule in place and I will compensate for the epoxy by adding .4-.5g of tape around the hosel.

[CF88]

1 hour ago, Ri_Redneck said:

Wrapping it around the hosel will be more accurate.

 

BT

That's a good idea. I wish I would have thought of that earlier, but now that I have everything broken apart again I was hoping to avoid having to build another test club. I do have the balance point and the overall weight (minus grip and grip tape) for the 8 iron test club I built as well as the calculated swing weight so I'm hoping I can use a swing weight scale and tip weights to get close enough.

Edited September 26, 2022 by CF88

[ARL67]

For my many builds over the years, epoxy is worth 0.2 to 0.3 SWP max.

[Howard_Jones]

On 9/26/2022 at 3:16 PM, CF88 said:

@Howard_JonesI have a quick question for a MOI iron build I'm currently working on. So far I have completed these steps

1. Heads weighed/recorded

2. Shafts cut to length and weighed/recorded

3. Built the 8 iron with no tip weight and determined the best amount of lead tape added for my swing

4. Cut off the grip and found the swing weight of the assembled club minus the grip and grip tape

5. Disassembled the 8 iron and re-weighed all pieces to determine the tip weight I need to get the desired swing weight

 

Now I'm at the point where I need to determine how much weight to add to each club in my set to get the correct swing weight slope. I will be using a swing weight scale to verify I have .5 swp increments between each club so my questions are more for my understanding of the process of MOI matching.

 

My question now is what is the correct way to approach head weight slope? I have used the search function and read every thread about MOI matching, but I can't figure out the correct way to approach this. I have read numerous times that a 7g slope with 3/8" between clubs would result in a roughly MOI matched set. Contrary to that I have also found your chart (shown below) in many MOI threads showing a progression based on a 9 iron where you add .7g to the 8 iron, 1.3g to the 7 iron, 1.9 grams to the 5 iron and remove 3.4g from the pitching wedge. Is the chart the most accurate way to go, and what formula did you use to determine the additional weight to add to each club above the 7g increments? I know you are one of the most experienced members on this forum regarding MOI matching so I want to make sure I'm following your instructions correctly and understand the underlying concepts. 

 

The set I am building is based on an 8 iron and includes 5-PW. My 8 iron head weight is 275g from the factory and I will be adding a 3g tip weight to obtain a dry swing weight of E3 with a standard DG S300 shaft. Based on a 278g head weight for the 8 iron, what would the correct head weight progression be? Thank you very much for any insight and help you can provide!

The summary of the standard head wgt slope and the correction factor, gives a head wgt slope of 6.4 grams, both ways from the #8 iron you started from who became 275+3 = 278 grams. Your target head wgt with tip wgt is:

 

Edited September 28, 2022 by Howard_Jones

[CF88]

2 hours ago, Howard_Jones said:

The summary of the standard head wgt slope and the correction factor, gives a head wgt slope of 6.4 grams, both ways from the #8 iron you started from who became 275+3 = 278 grams. Your target head wgt with tip wgt is:

Thank you Howard! That clears things up perfectly. Going to work on getting everything assembled in the next couple of nights.

[Kcct82]

Hi, will a starting head weight of 257g (8 iron head) and a club length of 33in (finished club length) alter the constant 6.4g head weight slope? Thanks!

[Howard_Jones]

11 hours ago, Kcct82 said:

Hi, will a starting head weight of 257g (8 iron head) and a club length of 33in (finished club length) alter the constant 6.4g head weight slope? Thanks!

 

SLOPE does not change, but the datas 257 gram #8 iron and play length 33 inches is numbers ive never seen