Mixing 3/8 with 0.5" length - shortcut to "MOI match" long irons

There is a growing interest for MOI matched irons out there, but longer irons often need a weight reduction who is no DIY job, but if you dont mind the idea of playing parts of your set with 3/8 length instead of the standard 4/8, there is a short cut to progressive SW for DIY as a alternative to MOI match the long irons.

As an example, your #6 iron is the iron you wants to duplicate, and its just fine as it is standard to D1-D2 or whatever value.

If your set is 3-PW, and #6 is your starting point, simply butt cut all irons longer than your #6

#5 Butt cut 1/8

#4 Butt cut 2/8

#3 Butt cut 3/8

Now your irons 3,4,5 and 6 will have a 3/8 slope and with progressive SW close to real MOI matching, while irons shorter can remain with 0.5", and then you just add some lead tape to the heads.

Using 3/8 in the long can both be a short cut to progressive SW from the iron you to start from, but also to improve your ball striking in those long irons in general.

Yes, the shorter lengths in the longer irons can likely help many get better results even w/o the MOI considerations. Certainly wont hurt any.

Just might have to tweak lie angles a little with the length changes.

Yes, the shorter lengths in the longer irons can likely help many get better results even w/o the MOI considerations. Certainly wont hurt any.

 

Just might have to tweak lie angles a little with the length changes.

Most iron sets has average 0.5* lie pr. iron or equal to 0.5* pr. 0.5", so if we like in my example goes 3/8 shorter on the 3 iron, then less than 0.5* more upright for 3# iron will bring it back to the lie it should have, so it really depend how deep we shall split it, since 0.5* off is only 1.5 yard at 150 yard out (more to the right without lie adjustment. for a right hand player, but sure, loft and lie angles should be tweaked right anyway, so for those who still plays them as off the rack, another improvement factor can be found here, but for most its not a DIY job.

Howard,

I should've read your thread before I posted a new thread earlier.

I was asking about modifying an existing 1/2" length increment set to a 3/8" increment set.

You have explained how to do the long irons beautifully and clear. Is there a fairly simple way of doing something similar with the shorter irons? Perhaps pulling a few shafts and moving them along to shorter irons? This would obviously leave a the set short of a few shafts, so they would need to be bought in.

Thoughts?

I don't really like the idea of adding lead weight.

You may have to do small extensions if you want 3/8 length separation in your short irons. Howard used a 6 iron as his starting point but that is a point that would fit that particular player. If - say your 8 iron is your best club, the 3/8'ths from here down to your 3 is still valid. Pick your starting point and shorten and lengthen as required.

I've found that the 3/8 progression to help on both ends of the set....less crouching over on the short irons and easier to hit the slightly shorter long irons.....key is to get the right sw/moi and length in that 6-7-8 iron that you are basing it on. I do think the progressive sw/moi matched set feels better then a set having the same sw throughout.

You may have to do small extensions if you want 3/8 length separation in your short irons. Howard used a 6 iron as his starting point but that is a point that would fit that particular player. If - say your 8 iron is your best club, the 3/8'ths from here down to your 3 is still valid. Pick your starting point and shorten and lengthen as required.

YES, depending on starting club, our specs changes, so here is 2 typical set ups, the first standard 4/8 in 3-PW and "standard 5W and driver". The second set is 3/8" with the same length extension to 5W and Driver, both with 2/8" as normal from #9 and into wedges. Both set ups is with #8 iron starting point. The 3. set up is with 3/8 on both irons and wedges.

Howard,

 

I should've read your thread before I posted a new thread earlier.

 

I was asking about modifying an existing 1/2" length increment set to a 3/8" increment set.

 

You have explained how to do the long irons beautifully and clear. Is there a fairly simple way of doing something similar with the shorter irons? Perhaps pulling a few shafts and moving them along to shorter irons? This would obviously leave a the set short of a few shafts, so they would need to be bought in.

 

Thoughts?

 

I don't really like the idea of adding lead weight.

Anything can be done, but we have to ask how far and how much it takes to make it.

This tread was only made to show a "short cut" for the long irons, (no matter starting point), but we cant use the chop saw to add length, so when we really want to make it all as it should be, this is not the way, then we should start out from blank sheets, so we dont get hung up in hindres not really there like if we started from blank sheets. Extension is possible, but....it was not the way i wanted to advice someone to go, but ok, it can be done and weight added "in our hands" like a extension is, dont make any problems really, so for those who will proceed from sawing the long might consider it.

What is missing from this scenario is lie angles. Howard, in every scenario (your charts above) you continue to cut down the length for every club - ending at the lob wedge. Are you continuing to bend the lie upright as you continue to shorten the wedges? If you are you must be ending up with a very upright LW?

I tend to steer towards constant length with identical lies as I progress trough the wedges.

we can make it what ever way we like, and im using 63* as standard Lie angle on SW and LW (-1* Flat) so we dont end up very upright in a 34.50 lob if we should go that short. We normally go down a bit on lie here to avoid to much pulled shots, so the GW to full swing will normally be the wedge with the most upright lie angle and then typical -1 on that value for SW and LW

Howard, I enjoy reading your ideas and utilize your knowledge as I experiment with my equipment. As I have been playing with a 3/8" progressive set for the last several years, this season I am trying a different variant on your latest idea.

Using my 7-iron as the middle of the set, I have the 7-iron at 3/4" over standard (37 6/8") and the 8-PW are 3/8" increments down from that. The 4-6 are each .5" increments going up so the 4-iron is 38 7/8". Since I am 6'3", my goal is to have the shorter irons longer and ease the stress on my back while the longer irons don't get to long to remain playable. This setup results in the shorts playing with a higher SW and the longer irons playing with a lower SW. I am excited to try them once the snow is gone here in Michigan.

MY lie angles are 3*-upright at this point, I can adjust as I need to.

Howard, I enjoy reading your ideas and utilize your knowledge as I experiment with my equipment. As I have been playing with a 3/8" progressive set for the last several years, this season I am trying a different variant on your latest idea.

 

Using my 7-iron as the middle of the set, I have the 7-iron at 3/4" over standard (37 6/8") and the 8-PW are 3/8" increments down from that. The 4-6 are each .5" increments going up so the 4-iron is 38 7/8". Since I am 6'3", my goal is to have the shorter irons longer and ease the stress on my back while the longer irons don't get to long to remain playable. This setup results in the shorts playing with a higher SW and the longer irons playing with a lower SW. I am excited to try them once the snow is gone here in Michigan.

 

MY lie angles are 3*-upright at this point, I can adjust as I need to.

Just remember that SW to "MOI" changes by club length like this

4/8" = 2/3 SWP

3/8" = 0.5 SWP

2/8" = 1/3 SWP

So when you mix lengths, you will also se "mixed SW values" so make sure you dont use the same SW progression for all, then they want be matched to "MOI" as you might want them. If you make a full bag, its not unusual to add SW value on hybrids, even more to woods, and the max for the driver, and in the other end, a bit extra on wedges vs irons, so i mostly make wedges with 2/8" and with 0.5 SWP to get them slightly above irons in resistance, and if we want them "heavy" use 2/3 - 1.0 SWP with 2/8" lengths in wedges

Im not sure if you plan to use the same length on all wedges or use 1/8" steps from #9 and further?

Howard, I enjoy reading your ideas and utilize your knowledge as I experiment with my equipment. As I have been playing with a 3/8" progressive set for the last several years, this season I am trying a different variant on your latest idea.

 

Using my 7-iron as the middle of the set, I have the 7-iron at 3/4" over standard (37 6/8") and the 8-PW are 3/8" increments down from that. The 4-6 are each .5" increments going up so the 4-iron is 38 7/8". Since I am 6'3", my goal is to have the shorter irons longer and ease the stress on my back while the longer irons don't get to long to remain playable. This setup results in the shorts playing with a higher SW and the longer irons playing with a lower SW. I am excited to try them once the snow is gone here in Michigan.

 

MY lie angles are 3*-upright at this point, I can adjust as I need to.

 

Just remember that SW to "MOI" changes by club length like this

4/8" = 2/3 SWP

3/8" = 0.5 SWP

2/8" = 1/3 SWP

 

So when you mix lengths, you will also se "mixed SW values" so make sure you dont use the same SW progression for all, then they want be matched to "MOI" as you might want them. If you make a full bag, its not unusual to add SW value on hybrids, even more to woods, and the max for the driver, and in the other end, a bit extra on wedges vs irons, so i mostly make wedges with 2/8" and with 0.5 SWP to get them slightly above irons in resistance, and if we want them "heavy" use 2/3 - 1.0 SWP with 2/8" lengths in wedges

 

Im not sure if you plan to use the same length on all wedges or use 1/8" steps from #9 and further?

The Driver will be in the D4 range, not sure on the hybrid yet. The PW will be 36 5/8", the GW - 36 3/8, the SW - 36 2/8", the LW - 36 2/8

Whoa, AmazinBlue, I just had that same idea and was going to ask Howard the same thing! I want to use my standard 7 iron as starting point, then go down 3/8 to 8 and 9, then down a 1/4 to PW, and wedges all the same. From 7, I want to use 1/2" increments up to the 3. Set would look something like this:

D- 44

3w- 42.5

5w- 41.5

3-39

4-38.5

5- 38

6- 37.5

7- 37

8- 36 5/8

9- 36 1/4

PW- 36

SW-36

So it sounds like my SWs may be all over the place, and not MOI matched if I don't do anything to the heads. Sounds like that may also impact how I need to do my lie angles. Would also affect gapping, decreasing gap in yardage between lower irons and wedges.

What do you think Howard? Is this crazy??

Whoa, AmazinBlue, I just had that same idea and was going to ask Howard the same thing! I want to use my standard 7 iron as starting point, then go down 3/8 to 8 and 9, then down a 1/4 to PW, and wedges all the same. From 7, I want to use 1/2" increments up to the 3. Set would look something like this:

 

D- 44

3w- 42.5

5w- 41.5

3-39

4-38.5

5- 38

6- 37.5

7- 37

8- 36 5/8

9- 36 1/4

PW- 36

SW-36

 

So it sounds like my SWs may be all over the place, and not MOI matched if I don't do anything to the heads. Sounds like that may also impact how I need to do my lie angles. Would also affect gapping, decreasing gap in yardage between lower irons and wedges.

 

What do you think Howard? Is this crazy??

yes and no, its crazy because you will be in big problems taking head weight down in those long irons. Ive been MOI matching sets of 4/8" for some years now, but strongly advocate using 3/8" for several reasons, and the most obvious is the head weight problems in the long, but using 3/8" steps also improve ball striking for most players in the same long irons if we can get them a tad shorter.

Going 3/8" does not mean you need a loft tweak, but lie angles would benefit from another slope, but we talk small numbers with 1 more up right on the #3 iron, and then just decimals for the others.

Consider this lengths, it would make the job way easier when we talk head weight.

Howard, I hope you don't mind me asking you a technical question?

You gave me some advice on the forum a few weeks ago with regard to changing my irons from 1/2" increments to 3/8".

Anyway, I've pulled all my shafts and cut them all length (39.5" 3 iron down to 36.5" LW, I'm tall so +1" over standard). I've weighed all the components and worked out the new weights for a specific MOI value (currently 2770kg/cm2 but I could change it).

However, it seems like I need to add most weight in the 3 iron and added weight is progressively less until I get to the wedges, where I need to reduce weight (by upto 10grams).

Does this seem normal to you?

I could further reduce the MOI target value but it would mean reducing a lot more weight from the mid irons and wedges.

I've calculated the MOI by using :-

(Mass of club x club length^2) + (Mass of shaft/3 x shaft length^2) + (Mass of grip/3 x grip length^2)/1000

Im thinking that the shaft/3 and grip/3 parts might be wrong, as the balance points of both are more central.

That was a lot at once...

Are you trying to make a SINGLE lengt set or is it something i misunderstand here? your numbers does not sound like a 3/8 set extended 1 inch

If you go 3/8 the regular head weight progression of 7 grams is very close to target, so this does not make sense to me, and thats the reason i suggest to use the short cut for DIY and just cut down "longer" clubs progressiv by 1/8" pr club. You will NOT be "perfect" then, but way closer than a SW matched 4/8 set, but yours dont seems to fit with thats, so what project is this really?

Thanks Howard.

It's a project to convert an old existing set from 1/2" increments to 3/8" and hopefully to MOI match them (as far as my limited equipment will allow). My head weight progression isn't regular - I'm getting gaps of between 4.0-10.0 grams prior to any adjustment. With my proposed adjustment I'm getting them around 4-7 grams.

Ok give me all specs

Where do you start from, the #8 iron?

Shaft in use ?

Head weight for all heads ex tip weights you took out.

I prefer doing this by using SW values, MOi is fine, but that formula is not correct, so let us take this by using the progressive SW calk to get a picture of what head weight changes needed to get them all matched.

I also wants to know if you start from your #8 (or what ever), did you add or reduce weight on that head to get it right*?

We need a starting point to do the math

OK. The shafts are DG S300 SL

3 iron = 239.6

4 iron = 244.7

5 iron = 251.7

6 iron = 255.7

7 iron = 264.0

8 iron = 269.3

9 iron = 277.5

PW = 282.3

50 = 292.5

56 = 301.0

60 = 299.1

I'm making the 7 iron the same length as original, the rest are adjusted 3/8" from that club. My calculations led me to think that I needed to reduce the head weight of 7 iron by approx. 2g.

Thanks Howard.

I'm using my 7 iron as the 'start' club and that is 38". Will this throw those new weights significantly off?

The balance point of the SL shafts is almost exactly in the centre.

The wedges (50, 56 and 60) were going to be all the same length so that I'm not reaching for them too much. So, PW = 36 7/8 and 50, 56 and 60 = 36 4/8.

ive adjusted all numbers and changed the post above (i have to delete photos all the time to be able to upload new)

Still about 10 grams needed down on your SW

The excel sheet im using is a sheet ive made to match sets like this, it also take care of tip trim depending on hosel specs and flex if you want a different flex slope or what ever.

You can download it here

https://www.dropbox....nd SW calc.xlsm

one error spottet....ive used SW progression on your wedges, like they was 2/8 shorter, but just download the excel file, and you can do all calks on your own

ive adjusted all numbers and changed the post above (i have to delete photos all the time to be able to upload new)

 

Still about 10 grams needed down on your SW

 

The excel sheet im using is a sheet ive made to match sets like this, it also take care of tip trim depending on hosel specs and flex if you want a different flex slope or what ever.

 

You can download it here

 

https://www.dropbox....nd SW calc.xlsm

 

one error spottet....ive used SW progression on your wedges, like they was 2/8 shorter, but just download the excel file, and you can do all calks on your own

Thanks Howard, that's great!

It seems like I wasn't too far off, perhaps a couple of grams here and there. I can finally get my bench grinder going!

Howard, Brilliant idea for DIY MOI matching, so simple.

I don't really understand what you are proposing for driver and 5w. We don't match those with irons typically.

Howard, Brilliant idea for DIY MOI matching, so simple.

 

I don't really understand what you are proposing for driver and 5w. We don't match those with irons typically.

Good question

MOI matched irons should be known for most in here now, but its correct, we normally dont set the hole bag to the same value, so we normally dont extend this progression both ways. It might be a bit different from player to player, but i found the good old SW scale to be good enough to match the others, so at the bottom on the irons (longest) we can just go flat on SW value, who actually means going UP in MOI/resistance as the club goes longer.

That will also depend on how long we play the others, but in the case above where his #3 iron ended as D 2.6 he would most likely be fine using either D2.6 or D2 flat for woods and driver. i also like a bit more heft in wedges than irons, most players do, so a steeper progression than the one who keeps MOI/heft flat might be used.

That means the SW scale is not that stupid after all, as long as we dont use it like OEMs where the #9 iron and the Driver has the same SW value, that DONT work, the length difference is to big so will MOI be. but experience has shown that we most likely do benefit from a weak progression in MOI from Irons to woods, but in the end its all a personal preference.

ive adjusted all numbers and changed the post above (i have to delete photos all the time to be able to upload new)

 

Still about 10 grams needed down on your SW

 

The excel sheet im using is a sheet ive made to match sets like this, it also take care of tip trim depending on hosel specs and flex if you want a different flex slope or what ever.

 

You can download it here

 

https://www.dropbox....nd SW calc.xlsm

 

one error spottet....ive used SW progression on your wedges, like they was 2/8 shorter, but just download the excel file, and you can do all calks on your own

Howard, I don't know why but I'm unable to view that file. It just goes to my dropbox account but there is nothing there.

Try this link

https://www.dropbox.com/s/bmnx54v7whdv2h1/Descending%20weight%20FCM%20and%20SW%20calc.xlsm?dl=0

Howard.....I see you still went up in sw with the wedges despite having same playing length, wandering reason behind that. Thx

I will offer my opinion on why Howard might have listed clubs with the same finished length with progressively higher swing weights.

For clubs that are used for partial shots a slightly higher swing weight can offer better feel for some players for the perception of the relative position of the club head.