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Dave Tutelman

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  1. I retired 22 years ago. The plan was golf twice a week with a bunch of friends whom I knew from work. That turned out to be 3 times a week: twice with my regular crew and once doing a free-lance walk-on to keep variety in the venues. I'll be 83 next month, and I'm still walking the golf course 3 times a week, year round. This is in NJ; I may get less than 3 times a week in the winter if the courses are closed for snow. But most weeks I can still get in 2-3. I found that was the most fun I could have, my best use of retirement. Sounds like yours has turned out to be something else. That's great for you! If the something else is more fun than golf, then you're in great shape. BTW, my son got a job in the mountains of AZ, and loves it there. His exercise is hiking in the bluffs and canyons around Sedona, which he can see from his front porch. Either way, whether you'd rather golf or hike, if it's what you want it's a great life!
  2. Julius, I'm an engineer, so it is a little hard for me to completely drop the technical stuff. But the first page of my web article about swingweight and MOI, while somewhat technical, avoids the math and keeps the explanation to words and pictures. You might find it a good introduction. Or maybe not. If you get through the first page, continue on until you are in over your head. No matter how far this is, you are going to learn a bunch about the topic.
  3. Thanks. That is a big help. But even more help is the explanation... I take that to mean that the HZRDUS' balance point is 2" higher than the ProForce. The rest of my response assumes you mean that. With that information, I can do some quantitative things with with swingweight. I can perhaps draw some qualitative conclusions about moment of inertia, but can't get really quantitative. (Remember, swingweight and balance point are static measurements. Moment of inertia is dynamic; it can't be deduced from just weight and balance point, but needs more detailed information about the weight distribution.) If this discussion leaves you wanting more, we can talk about further tests. For purposes of discussion, let me give some intuitive names to the shafts: S1-A is "long". It is 5/6 of an inch longer than the other two. S1-B is "nominal". S2 is "highBP". (I prefer that to "counterbalanced", because the latter can be done in so many ways. This one is same weight but a higher BP, which I would not have though of as counterbalanced before this discussion.) So here are my observations. The numbers relate to the H1 head, but the numbers and the observations are similar for the H2 head. "Long" is 4.5 swingweight points higher than "nominal". If you asked me to guess off the top of my head, I'd have guessed 5 points, using a rule of thumb of 6 points per inch of length. If you look at more precise tables of sensitivity, you see driver a little less than 6, so the 4.5 points makes even more sense. "Long" is 127kg-in^2 higher MOI than "nominal". That is a little higher than I would have guessed but really pretty close. Sensitivites say that a swingweight point is worth about 20kg-in^2 for more-or-less similar clubs, which these are. By that rule of thumb, 127kg-in^2 is a little more than 6 swingweight points. But then, MOI is proportional to the square of length, so changing the length might change the MOI faster than the swingweight. So, still a very sane result. "HighBP" is 3 points lower swingweight than "nominal". Let's take a raw shaft weight of 71g (130g assembly - 51g grip - 8g adapter), and move the balance point 2 inches up the shaft. That will reduce the torque on the swingweight scale by 71g*2in=142g-in. Since a swingweight point is 50g-in, that is a drop of 2.8 swingweight points. Very close match to the 3 points that was measured. "HighBP" is 32kg-in^2 lower MOI than "nominal". Again, using a rule of thumb of 20kg-in^2 equivalent to a swingweight point, that is only 1.6 points; that is considerably less than the 3 points of actual swingweight that we lost. This is the sort of number I would expect. Counterweighting doesn't do nearly as much for MOI as for swingweight. In fact, a pure counterweight -- a weight added at the butt -- should actually increase the MOI. But I can't make a quantitative calculation here. That is because I don't know the actual weight distribution of the "highBP" shaft, and I would need to know it for an MOI calculation. Just knowing how much the BP moves tells me static stuff, but nothing dynamic. So this is a pretty good sanity check for the theory (by my calculations) and your measurements. If we want to be more precise, we would need to do an actual counterweighting of the "nominal" shaft and compare that. I'll leave it to you whether you want to go that additional step. It will be quite a bit more work. The swingweight part is pretty easy; just tape a weight to the grip outside the shaft even with the butt. But I don't know if this can be done rigidly enough to clamp the butt in the MOI meter and expect the weight to follow exactly; you may have to stuff the weight into the shaft, which means removing the grip and re-gripping. Whatever you feel like doing. If you do more, I will gladly analyze the results. This has been a fun discussion. Thanks much! DaveT
  4. BigBoiGolf, please help me out here. I'm having a lot of trouble interpreting this experiment. I tried to make a table out of your lists (thanks for the color-coding; I think that helped), but I am failing on some very important considerations. Let me ask a very few questions, and see if the answers allow me to make the table so I can view what is going on. Is "installed length" the same as "club length with shaft installed"? If not, then what is installed length, and what is the club length? Where is the counterweight? I see three shafts of roughly equal weight with grip and adapter. I don't see anything that suggests a counterweight. Why two heads? Since you have adapters, it seems one head would answer the question just fine. Why more than one installed length? That should not tell me much of anything. Two of the shafts are pretty much the same length, the other is a good 3/4" longer. Let's see if the answers to these questions let me see what the experiment should show. Thanks. If you want to continue this discussion in private (outside the forum) and come back and report results, contact me at dave@tutelman.com.
  5. Let me predict what will happen. IIRC, you have an GolfMechanix MOI meter. I gather from what you say, you intend to compare two drivers with the same head weight (I hope approximately the same head design), the same length, the same shaft model, the same grip, but one will will have extra weight in the butt of the shaft. (That's what I interpret "counterweight" to mean.) They will have very similar MOI measurements. The counterweighted one will be slightly higher, but the difference will be very small. But the counterweighted driver will have a noticeably lower swingweight, by about 3 points for each 10 grams of counterweight. Please let us know how that works out.
  6. That is part of it, perhaps even a big part. But weight (really mass) and force are useful for static feel and motion in a straight line. As the club picks up speed, more of the motion is rotational. At impact, 80% of the clubhead speed is due to angular velocity and only 20% to linear. (Could be more biased than that; I've seen studies go down to 87-13, but none more equal than 80-20 for decent golf swings.) So we need to account for angular motion as well. That means torque and moment of inertia, which are the angular equivalents of force and mass. Weight and CG reflect the zeroth and first moments of the club's mass. In order to reflect rotational acceleration/motion, you also need the second moment of the mass -- the moment of inertia. How does this fit golf reality? In fittings I have seen where each club was separately fit until they all felt the same, the set was very close to a moment of inertia match and not very close to a swingweight match. That means it probably isn't all about the transition nor static feel, but rather about feel as the club approaches impact -- rotating more than translating.
  7. That's a "yes but". People with a swingweight scale who don't understand it thoroughly might conclude "swingweights all over the map" when in fact the build accurately accomplished exactly what was needed. A properly MOI-matched set will not all be the same swingweight. Unless you graph the swingweights and notice they are carefully sloped (but not identical), you might conclude this is a sloppy set.
  8. It is certainly worth noting that this progression of swingweight is a step in the direction of MOI matching. In fact, if the swingweight changed by about 2/3 of a point from each club to the next, it was a very good MOI match. Bobby Jones's career predates swingweight. But I have read that his clubs were matched by the head weights times the square of the length. This is also closely related to an MOI match.
  9. We're very much in agreement here, BigBoiGolf. Even to our opinion of what Russ Ryden is doing. Just a few things I'd like to point out. A lot of the discussion -- too much in my opinion -- is centering around the fact that 14" is not a pivot or fulcrum for anything real. While true, that completely misses the point. The inventor of swingweight, I am almost sure, picked 14" empirically, because it simulated moment of inertia across a wide variety of clubs. That, and not any physical reasoning, is behind the number 14". If you look at the graphs I mentioned in my previous comment, you will notice that swingweight and moment of inertia track very well against one another, if all you vary is head weight or overall shaft weight or club length. If you consider swingweight to be a "cheap and dirty" way to measure moment of inertia, the errors are less than 10% for each of those club properties. (That relationship falls apart completely when you look at grip weight. We'll get back to that in point #3 below.) Until the 2000s, it was quite expensive to actually measure MOI, which cannot be done statically. (Well, either expensive or tedious and math-intensive.) So a swingweight scale was a remarkably good shop tool for getting an approximate MOI match. Very few of the clubfitters who used the tool every day knew that, but physics and history strongly suggest it is true. With 20:20 hindsight, here are a few things we need to think about when we think about swingweight: I have shown elsewhere that a really good MOI match can be obtained by doing a swingweight match with a sloped swingweight of a little over one point per inch of club length. This gets much closer to a true MOI match than a straight swingweight match does. All of this -- the origin of the swingweight scale, the sloped swingweight match, etc -- depends on varying length and clubhead weight only. There is a second correction for changes in shaft weight. Anything else simply does not fit the model, and can give nonsense results if you do them to match swingweight. That includes different weight grips, counterweighting, lead tape in the middle of the shaft, etc. The talk about a D-0 telephone pole is no more than a joke based on this truth. If you think about when swingweight was invented (the 1940s), there was not much choice in shaft weight and even less in grip weight. So swingweight worked fairly well as an MOI surrogate for the clubs you could build back then. With today's ability to play with shaft weight profiles and grip weights, swingweight is no longer a reliable surrogate for MOI -- unless you are careful not to use those "knobs" to adjust your clubs.
  10. BigBoiGolf implies that you want to build to the club's moment of inertia rather than swingweight. I've been saying this for about 30 years. At that time, MOI meters were somewhere between expensive and nonexistent. So I came up with a way to MOI-match a set of clubs using a swingweight scale. It is only fairly recently that reasonably priced MOI meters have become available, and by that time I was very comfortable with estimating MOI with my swingweight scale. But my goal is still MOI matching. Here are a couple of articles I wrote about why swingweight matching is nonsense, how to do MOI matching with a swingweight scale, and my first cut at estimating MOI match with a swingweight scale (from 30 years ago, with the help of TJ Field).
  11. Well said. My experience was similar but more so than that. Until my youngest was in high school, I immersed myself in the family. That was much to the detriment of my other activities, including golf, and worth every minute of it. I was part of my children's lives for their formative years. If that meant I was their soccer coach, monitored their piano practice, was there if they needed homework help, then so much the better. Even if that meant I didn't even play golf once a year. I got back into golf seriously when they got to high school. Think about it. Think about your situation. Teaching is a full-time job. If you're a teacher, you know that parenting is very important -- and also time-consuming. If you have time for regular golf, then either your work or your family is being short-changed.
  12. One day in September of 1996 (wow! almost 30 years ago), I was in Newark OH. I spent the morning on a tour of Dynacraft and the afternoon on a tour of GolfWorks. I was there for a 3-day golf event, but the Friday got rained out. The host of the event "had connections", so he set us up to do this instead. Ralph Maltby was out of town, so a marketing guy led the GolfWorks tour; but Jeff Summitt showed us around Dynacraft and spent an hour answering questions afterwards. (Tom Wishon left Dynacraft a couple of years earlier, so we didn't get to talk to him.) I documented the visit (mostly the Dynacraft visit, where we had Jeff as the host) in an article that's on my web site. Come to think of it, that weekend was the annual convention of the Association of Clubfitting Professionals (now long defunct); Jeff had to leave about lunchtime to catch a plane to the convention. I bet that's why Ralph was missing when we got to GolfWorks. My impression of the Maltby stuff was that it was kind of ugly at the time, but effective. Their cosmetics are much better today. I believe the Maltby Playability Index was definitely on the right track, and they were after good numbers on that scale. That meant they were selling stuff for the average golfer. Tour players probably didn't need it, and most low handicappers of the time turned their noses up at it. Back in the '90s, I built a driver with a Maltby wooden head and a rather flexy graphite shaft. It worked pretty well, and was my gamer for most of a year.
  13. I love the feel. Not squishy, but it's not hard and never seems to get hard nor cracked. I have also found that the tack not only lasts a long time, it is restored to "almost new" with a good washing (water and strong detergent or de-greaser). A litle history here. A friend who is a reseller of a lot of golf components first told me about Star almost 20 years ago. Since I tried them back then: They have been the only grip I use on my own clubs. I have never had to replace one due to wear nor age. My current irons have had the same grips for over 400 rounds and their feel and tack are still very good. (Yeah, I know that speaks to Star's and Pure's business model. So be it!.) I blow grips on and off without tape. (2" of tape over the butt to get it started makes it easier, but far from necessary.) In fact, I just lengthened a driver, which involved removing the grip (with an air compressor), putting in a shaft extension, and blowing the old grip back on. No problems, and the old grip is still fine. The formulation (common to Pure and Star but no other grip I know) retains its elasticity as long as my experience with them.
  14. It does indeed. If that is important to you, then I fully understand why you are going to miss Pure. I'm an engineer. Yes, I appreciate aesthetics, but my primary concern is function. In that regard, Star and Pure are quite similar. Star does offer a pretty good color choice, but (a) nothing as eye-catching as that neon yellow, (b) only solid colors (I think dispersed into the rubber) -- nothing like the black logo on the light-colored grip. But check it out; you might like it.
  15. Pure was originally a spinoff from Star Grips. The folks who left Star for Pure were unhappy about Star's inattention to cosmetics and marketing -- but NOT the formulation of the grips. Star is still in business and still my favorite. Try them. If you liked the feel, handling, and longevity of Pure, you should like Star.
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