Making Matched MOI Iron Set

[texbychoice]

Have assembled a couple iron sets for myself, one set for a friend, and other individual clubs. Ready to do another set for myself. After quite a bit of reading leaning toward the matched MOI route due to Tom Wishon shared knowledge. Formulas found on the Internet to calculate MOI seem straightforward. However, formulas found for swing weight cast doubt on the reliability of Internet information. Swing weight formulas predict an outcome way different than measured results.

 

I know the weight of all the components. For example, 7 iron calculated SW is C8.8. Actual measured SW is D0.5. No way epoxy and grip tape could account for the difference. Of course, formulas are an estimate. Shouldn't the estimate be closer to measured?

 

Would appreciate feedback if anyone has done MOI matching.

[Stuart_G]

There are good estimates and bad estimates (for both swing weight and MOI). And even the good ones depend on accurate information being put into those equations. e.g. actual measured cut shaft weight (good) vs the uncut weight specs found on a web site (bad). Balance points +/- 1/4" or worse bad, +/- 1/16" good.

 

For swing weight, if it doesn't consider or involve measuring the actual shaft or club balance point, forget it and find something else. Even if it does, you're still looking at +/- 1-2 sw pts at best with any calculation or estimate.

 

So If you're building that many sets, it's time to invest in a swing weight scale, particularly if you do any building for others.

 

As for MOI matching, the "best" approach short of actually measuring MOI tends to be to use an actual swing weight scale and use SW increments based on the length increments. e.g. 1/2 SW for 3/8" length increments or 2/3 of a SW pt per 1/2" increments. And that's really just for the irons in a set. It's not for matching irons to hybrids or hybrids to fairways, etc.. The different type of clubs (wedges, irons, hybrids, fairways, driver) should be fit independently anyways. You don't use a single MOI value for all clubs in the sets.

[texbychoice]

Thanks for the reply, Stuart. Have a SW scale and scale to weigh components to tenths of grams. Read writings and watched videos made by Tom Wishon. He is a master club fitter with vast experience and extensive tools at his disposal. What he says about MOI matching is intriguing. Prepared a spreadsheet with component weights and calculated MOI and SW. Inclined to give it a try, unless there is wisdom out there saying not a good ides.

[Yrrdead]

http://www.tutelman.com/golf/design/swingwt4.php#measure_moi

 

He has a ton of great info on his site. Buckle up.

[Stuart_G]

Thanks for the reply, Stuart. Have a SW scale and scale to weigh components to tenths of grams. Read writings and watched videos made by Tom Wishon. He is a master club fitter with vast experience and extensive tools at his disposal. What he says about MOI matching is intriguing. Prepared a spreadsheet with component weights and calculated MOI and SW. Inclined to give it a try, unless there is wisdom out there saying not a good ides.

 

SW matching vs MOI matching is really a matter of personal preferences so there is no reason not to give it a try. My only suggestion is if you have a SW scale, just use it and don't waste your time with the possibility of inaccurate calcs on a spreadsheet.

[jth3333]

Get an auditor moi scale. Moi your favorite iron and start there. Decide if you want 1/2 inch increments or 3/8 inch.Dependent upon shaft choice and flex. I retro moi’d my first set at 1/2 inch with lead tape. The second set I had bulit with 3/8 inch increments. Same shafts both cases. I have an auditor. Technically I believe you start with a light club and add weight until it feels good and consistent.Then continue to add weight until it changes performance for you.

[Carvallo Golf]

MOI matching is good if the MOI fitting is done correctly, and constant MOI is not always best fit. I have MOI fit people with ascending/descending MOI and also curved MOI. Best practice is to fit throughout the bag. When you get fitted this way, SW or MOI can both give good results.