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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  • 11:40AM - Jun 10, 2010RE: Maltby Playability Factor (MPF) for Putters

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    Mr. Maltby, wanted to know if you make a heel-toe weighted putter with minimal off-set (1/2 shaft or there abouts)?

    Thanks

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  • 1:42PM - May 12, 2010RE: Maltby Playability Factor (MPF) for Putters

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    msf, the list was never put up on the site. I have measured quite a few putter heads for MOI and it will be something that will probably be published in the future after the new book comes out. I put some of them in the new book along with pictures.

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  • 4:33PM - May 11, 2010RE: Maltby Playability Factor (MPF) for Putters

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    • msf

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    Ralph,

    I read the article and it says “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”.

    Where can I find putter MPF’s on your website?

    I do see that you have putter mpf’s listed in the new GW catalog.

    Thanks, Mark

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  • 6:58AM - Dec 24, 2009RE: Maltby Playability Factor (MPF) for Putters

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    Ralph:

    I have used the Ping Zing 2 putter for over 15 years. I have tried different putters but have always gone back to this one. It feels more comfortable than anything else I have ever tried. This putter seems to be very light compared to newer putters. Given this, I have a few questions and here they are;

    Is there anything I am giving up by sticking with a putter that is several years old like this one?

    Have you run MOI tests/analysis on the Ping Zing 2 putter? Does it have a MPF?

    Lastly, this site is a great resource and I enjoy reading it very much.

    Thanks

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  • 4:14PM - Aug 20, 2009RE: Maltby Playability Factor (MPF) for Putters

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    I am in the market for a new putter and am looking for a face-balanced (or slight toe hang) putter with good MOI without being a huge branding iron. Do you have MOI numbers for Odyssey White Hot Tour #5, Scotty Cameron Newport Fastback 1, or Ping iWi B-60? Will the new putter book have the MOI list? When is it due to come out? Thanks!!

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  • 2:28PM - Jun 24, 2009RE: Maltby Playability Factor (MPF) for Putters

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    • Okie

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    Thanks for the information! I reckon this makes the Odyssey Tri Ball SRT almost twice as good as the old anser. Since I putt twice as bad as I used to then I guess it’s a wash!

    Kidding of course but I really wish we had the internet when I was in the golf business! This is good stuff! :)

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  • 10:40AM - Jun 24, 2009RE: Maltby Playability Factor (MPF) for Putters

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    thepig-pen, I did quite a bit of testing on face lines in putters and also curved faces. All the data indicated that to be the most consistent in putting a golfer needed a putter head with 3 to 4 degrees loft, a very flat face and as smooth a face as possible (fine milling marks are OK). So, most any putter head material will work and putter face inserts are fine, but lines put in the faces of putters can make the striking surface less consistent.

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  • 7:29AM - Jun 23, 2009RE: Maltby Playability Factor (MPF) for Putters

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    Ralph,

    A small line from one of your posts at the start of this topic jumped out at me.

    " . . . .and they don’t cut special lines in the face to influence the balls roll. "

    Are you saying the grooved faces of putters like the YES! and Rife models hurt the playability of a putter? It seems like everybody is doing that in some form or fashion now. I think either Rife or YES! (or both) had “test” data on their site to promote their technology. Do you have data that shows otherwise?

    Maybe I’m reading too much into this small line taken out of a post from 2007, can you elaborate?

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  • 5:06PM - Jun 19, 2009RE: Maltby Playability Factor (MPF) for Putters

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    Okie, I have the Odyssey 2 ball White Hot and I also have the Odyssey Tri Ball SRT. The 2 ball Moment of Inertia is 3553 grams per centimeter squared. The 3 ball MOI is 8520 grams per centimeter squared. For reference, the old Anser’s were in the 4300 to 4900 range.

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  • 12:14AM - Jun 18, 2009RE: Maltby Playability Factor (MPF) for Putters

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    • Okie

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    I was looking to compare numbers I saw in the mid 80’s to what you had. I attended a PGA business school which had Dave Pelz as a speaker and he introduced us to MOI and his 3 ball putter. I was looking into buying an Odyssey three ball putter and was curious how it compared to the old pelz 3 ball.

    Since then I went ahead and bought the Odyssey putter. Feels like crap compared to my 20 year old anser but I figure it will take some getting used to.

    If you have numbers on the Odyssey three ball putter and the old ansers that would be of interest to me.

    Thanks

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