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DIY MOI self fitting

 sliight ·  
sliightsliight Members  11WRX Points: 31Handicap: 6.1Posts: 11 Bunkers
Joined:  in Avg Joe Swings Stiff and Below #1

Ordering some new (used) clubs and going with an inch longer vs the 1.5" I've been playing for years. Hopefully find a set factory made so head weight a bit lighter.

I was hoping people could chime in that have done moment of inertia matching and advise if they feel like it really helped.

I found this calculator and am curious what people think on it. Not sure I understand the measurement of pendulum... Seems like you just let it swing back and forth from a big start and count, then did the math.

There's also references here to skipping all the science and just using shoe spray to hit 5 shots, note dispersion and ball flight, add some lead tape, then repeat. Keep repeating until tightest dispersion on the club face, then that club is done. Repeat for each club...all of this is moot of course if head is overweight already...

I kind of feel like it would be best to start with best feeling club, do shoe spray test until dialed, then use MOI calculator to see what it is. Then use calculator to determine MOI for each club. From that it would be easier to get a head start on what it should be. Adjust, test by hitting, then tweak to finalize.

The more I read the more it seems like it really does improve consistency of impact, which just means more consistent distances and control.




  • BREWMASTER95060BREWMASTER95060 Members  195WRX Points: 41Posts: 195 Fairways
    Joined:  #2

    I have used that website

    i like it

  • GolfWRXGolfWRX Warning Points: 0  11 Members Posts: 11 #ad
    Joined:  ...

  • rx7markrx7mark Members  73WRX Points: 61Posts: 73 Bunkers
    Joined:  #3

    Personally I like to build a MOI matched set that is also MOI Balance Index matched or MBI matched. This matches the club balance point and MOI, but works best with clubs built with ascending weight shafts and built to 3/8 club increments. A guy named Monte created a spread sheet a few years ago to help do this and if done right makes the clubs feel and swing the same. It's really amazing but a little hard to do well.

    See this thread for more discussion and a copy of the spreadsheet with a technical explanation.


  • Stuart_GStuart_G New HampshireMembers  25555WRX Points: 1,939Posts: 25,555 Titanium Tees
    Joined:  edited Aug 1, 2020 8:46am #4

    For iron sets, most people do really well getting a good approximation of a MOI matched set by using a swing weight scale and a fixed swing weight progression. Assuming the exact same grip and shaft model, the swing weight should get lighter by 2/3'ds of a SW pt per 1/2" the club gets longer in length. Or what works well with most standard iron sets is to change the length progression from 1/2" to 3/8" and use 1/2 sw pt increments. That will require less adjustments to the head weights than the more typical 1/2" increments.

  • Howard_JonesHoward_Jones Members  11592WRX Points: 2,272Posts: 11,592 Titanium Tees
    Joined:  #5

    Thats way to complicated for most, and like Stuart writes, using the SW scale to get close to actual flat MOI is way easier using a offset factor of 1.33 SWP pr inch. If you have a iron set where the #9 iron is "just perfect", we can duplicate that club (modify the others to get a resistance like the #9), very easy, so i made 6 different options for play length progression, all using the #9 as starting point. All you need to do is to butt cut the others to get the length progression slope you want from this chart, and add the needed weight to each head that belongs to the same length slope. This set up assumes the #9 works very good as it is, and that the rest of the set has the same SW value now, and clubs is 4/8" apart. All values is "relative" to the #9 iron, so it does not matter if that #9 iron is "standard" or plus 0.5" or what ever.



    Unless you are a former Customer or someone i already have a PM dialog with, i want reply to tech questions on PMs.

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