Maltby Playability Factor (MPF) for Putters

If everyone struck a putt on the horizontal center of gravity location of the putter face there would be no need for putter head playability factor. We all know this is not the case. The actual ball impact point on the putter face is both a function of the golfers’ ability and how long the putt is. It is a fact that better players usually hit the ball more consistently close to the center of gravity and for most all players, the longer the putt, the harder it is to hit the actual putter face center of gravity.

A term that has been commonly used over the years is “sweet spot.” I think by now all golfers realize that the size of this so-called sweet spot varies from club to club, whether we’re talking about putters, woods or irons. There are a number of factors that help to determine a putter head’s sweet spot. However, there is one very significant factor that determines this. That factor is the putter head’s Moment of Inertia (MOI). MOI is simply defined as a measurement of the putter heads resistance to twist or turn when acted on by an outside force. An example would be a putt struck off-center or more correctly a putt not struck on the putter head’s horizontal center of gravity location. This will make the putter head twist or turn at impact. The farther off-center the hit, the more twisting that occurs. If the hit occurs on the center of the face, then no twisting occurs and MOI has little meaning. The more twist that occurs the more the putt will usually be off the intended line.

Moment of Inertia (MOI) is mainly responsible for the size of a putter’s sweet spot.

This brings us back to sweet spot. The higher the MOI, the larger the sweet spot and conversely the lower the MOI the smaller the sweet spot. Obviously, it would be very important for a player who has trouble hitting the putt consistently near the center of the putter face to use a very high MOI putter head. Common features of high MOI putter heads are head shapes with more material in the heel and toe areas, longer putter head lengths and heavy weights such as brass, lead or tungsten added in the heel and toe areas.

The Maltby Playability Factor (MPF) places putter heads in different categories. These are the similar categories that are used in iron head MPF but putter heads are calculated differently. Since the MOI is mainly responsible for the size of a putter’s sweet spot, it is the predominate mass dimension used for determining the putter heads MPF. The MOI is taken accurately and measured in inch-ounces squared or grams per centimeter squared. This MOI number is used, along with other weight distribution data to calculate the MPF category the putter head fits into.

Putter head playability based on Moment of Inertia and other mass and dimension properties was thoroughly tested and proven using actual robotic putting machines and ultra high speed photography. Hundreds of GolfWorks School students visited the Golf Club Design studio throughout the year and were actually shown these capabilities with live demonstrations. Every school student came away with a much better understanding of how putters work, how to fit putters better and to say the very least, they were all amazed at the differences in putter playability from the various MPF categories.

The complete method and all explanations for determining putter head MPF will be published soon in a new book titled The Maltby Playability Factor, Understanding Golf Club Dynamics – Book Three, Putters. Until the book is published I have included on this website a listing of putters and their MOI’s that can be compared by the reader. This listing will be updated periodically as new putter heads are measured.

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  • 11:47AM - Mar 10, 2008RE: Maltby Playability Factor (MPF) for Putters

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    Antony, I have been working on the putter MPF book for a couple years now. Of course it is stalled a little because I need to get out the new fiting book and also the wedge MPF book. I have measured over 200 putters for moment of inertia which is one of the more key variables in MPF for putters. This was part of the research to get a baseline on where the industry stood and also putter head historical data. I really have some great stuff and currently about 100 or so drawings and some photos explaining everything you ever wanted to know about putter playability. I needed to make up special putter heads for the robot and also for player testing. They are basically adjustable in MOI and center of gravity. I have decided to put a little bit of this information in the new fitting book because it applies to modern fitting techniques for putters.

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  • 6:16PM - Mar 9, 2008RE: Maltby Playability Factor (MPF) for Putters

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    Quote:

    Originally Posted by Richard

    Ralph,

    Can you comment on the MPF for an Odyssey White Hot XG #7 and #8 putter heads? And the Ping G5i Ug-Le? I have tried them and like the feel, but I want to make sure they are technically sound.

    Thanks

    Ralph Is there a MPF for Putters?, I haven’t found in your web page but in mi mind I remember I read you wanted to publish one…Regards

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  • 4:56AM - Mar 8, 2008RE: Maltby Playability Factor (MPF) for Putters

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    Thanks, Ralph! That makes good sense now (google gave me a different conversion). It’s very generous of you to respond so quickly!

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  • 3:45PM - Mar 5, 2008RE: Maltby Playability Factor (MPF) for Putters

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    fronesis, here is how it works; Lets say that a putterhead has a 40 oz/in squared moment of inertia number. You simply take 40 and multiply it by 182.9 and you will get grams/centimeter squared. So, 40 X 182.9 = 7316 gr/cm squared.

    I would agree that the GolfWorks really needs to put the actual moment of inertia of every putter next to it in the catalog. I think I can get this done.

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  • 9:34AM - Mar 5, 2008RE: Maltby Playability Factor (MPF) for Putters

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    Sorry, I wrote along post but it was evidently too long.

    Ralph, I LOVE what you do here and buy lots of stuff from you, but please give us gm/cm2 MOI ratings for your putterheads so that we can make reasonable comparisons.

    The link that b***player provides below is only confusing, since if you convert 40 oz/inch2 (from that link) into gm/cm2 you get a number that’s TINY compared to the 5000 gm/cm2 MOI rating that we see on drivers, and also on a large number of golfsmith heads.

    I want a new Golfworks head that’s centre-shafted and with an MOI as high as my design 09, but I want more options than the max moment, and right now I don’t have enough info to go on.

    Thanks!

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  • 8:20AM - Jan 1, 2008RE: Maltby Playability Factor (MPF) for Putters

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    GolfWorks putters list the MOI for the most part. I’m not really sure about a listing for all putters. It would be interesting to see. Here’s a bit about Putter MOI from the GolfWorks website.

    http://www.golfworks.com/article.asp?ai=169&;bhcd2=1199197182

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  • 8:58PM - Dec 31, 2007RE: Maltby Playability Factor (MPF) for Putters

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    Where exactly is the listing of the putter MOI’s?

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  • 12:02PM - Dec 31, 2007RE: Maltby Playability Factor (MPF) for Putters

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    Just fyi, I’m hoping to win a Maltby Max Moment putter soon, and I’ve decided to sell my Odyssey White Hot 2-Ball. I was immediately struck by the stability of the Max Moment, and, like I said, I sank a couple putts too.

    I’m keeping my MacGregor Bobby Grace V-Foil MOI M5K at least for now. I still plan to trim it down to 34”.

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  • 4:04PM - Dec 19, 2007RE: Maltby Playability Factor (MPF) for Putters

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    I tried out a 34” Maltby Max Moment putter today at Golf Galaxy. It almost swings itself, and I sunk 2 putts with it from over 10’. I may seriously consider it when I start getting into building.

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  • 4:41PM - May 2, 2007RE: Maltby Playability Factor (MPF) for Putters

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    Richard, I am a fan of both the Ping and Odyssey putters. They both put adequate loft on their putters and the faces are flat. If the putter has a double bend shaft, it will usually be installed correctly and they don’t cut special lines in the face to influence the balls roll. Soon I will have posted on this website the moments of inertia of over 100 current and past putter models. Regardless of which putter model you pick, be sure to at least have the length and lie properly fit to you. PS I have not measured the Ping Ug-Le as yet.

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