AL: Aha, lest we get things wrong in the translation, Mike quit working at Golfsmith before he contacted me to probe the waters about possible gainful (well I hope it is!!!) employment. And I am glad he did too because he is really working his tail off to get us up and running now and doing a SUPERB job! With that set straight, I have to say that any of the official research that was done with the Iron Byron at Golfsmith is the property of Golfsmith, and we respect that. But in this case, any of the testing done on the SST PURE process is the property of Dick Weiss because that was a part of the agreement whenever testing on shafts done with his system was done at GS while I was there. So alas, we can't help you in this area.
TOM W -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Al Taylor Sent: Monday, December 30, 2002 4:50 PM To: [EMAIL PROTECTED] Subject: Re: ShopTalk: shaft flex v.s. frequency Well guys, I can't find the info. TT made a presentation at one of our PCS Expo's, a few years ago, (read blatant plug for the PCS) and this was discussed then. I have, somewhere, my personal "profile" from the then current shaft lab equipment. There may be some info in that, but not sure and not sure where it is now. Maybe someone else has the requested info. A call to Memphis may help. I donno. Tom Wishon, a subscriber to this esteemed forum, has stolen Golfsmith's number one number Cruncher, and has him under employment. I wonder, if Tom reads this, if he could ask Mike Duggan to post a note on the findings. This info was presented at one of the GCA shindigs a couple of years ago. I believe I am accurate in stating that they found that by aligning the soft side of the FLO down the target line, they experienced a dramatic tightening of the face impacts around the sweet spot. The tests were conducted with an Iron Byron. Hope this helps. Al At 06:11 PM 12/30/2002, you wrote: >Thanks for that info Al, do you have any idea where I could find >information on what was done? Either by TT and/or Golfsmith? > >Alan > >At 04:00 PM 12/30/02 -0500, you wrote: >>Alan, >>We went through the 1/2 cycle discussion several years ago. You might >>want to look at True Tempers research that they did with their Shaft >>Lab. It is amazing what the head does in the last few milliseconds prior >>to impact. Toe Bob, I think, is what they call it. They found that pros >>had much less to nil amount of toe bob, compared to amateurs. They >>figured it was their ability to maintain a load on the shaft, due to >>continuous acceleration, into impact. The concept of spine aligning, >>which was later indicated by tests done by Golfsmith, tended to minimize >>this bobbing affect. The results were more "on center" hits. This, in >>effect, made for longer hits, by way of reducing distance loss due to off >>center hits. It's a maddening game some of us play, trying to fit golfers. >> >>Al >> >>At 10:48 AM 12/29/2002, you wrote: >>>Hi Al, >>> >>>Not from my perspective, I think that is exactly correct. Also, keep in >>>mind that a shaft only undergoes a half cycle of oscillation during a >>>golf swing (at least the part of the swing we care most about). Things >>>that happen after many cycles of oscillation don't really effect the way >>>the club hits the ball. >>> >>>Regards, >>> >>>Alan >>> >>>At 03:20 AM 12/29/02 -0500, you wrote: >>>>Well Alan, >>>>We may be getting there, but will let you be the judge. I understood >>>>your example and how the formula applies, but couldn't equate/apply the >>>>example to a golf shaft. Instead, I pictured two parallel springs (or >>>>a thick bar and a skinny one), one stiff, one weak, both tied together >>>>at both ends. I can intuitively now see how the force required to bend >>>>this in either direction would be the same and also how that would >>>>apply to a golf shaft. I just can't see how the formula applies in my >>>>case. (probably just as well too!) >>>> >>>>Anyway, assuming I am getting close, let me make a proposition. I >>>>would say that once you have found this point in a shafts axial >>>>rotation that allows it to oscillate in a flat plane, when twanged as >>>>we do it, and that since the force to bend it a certain amount in >>>>either direction would be the same, then the shaft will respond the >>>>same from equal but opposite direction pulls off neutral. That being >>>>the case (hahah I hope), it would then seem to me that it would make no >>>>difference which side of this planer oscillation was placed towards the target. >>>> >>>>Did I get too brave? >>>> >>>>Al >>>> >>>> >>>> >>>>11:41 PM 12/28/2002, you wrote: >>>>>The simple answer is that the two legs have the same load on them and >>>>>the paper leg is weaker than the steel one. But that really isn't a >>>>>good analogy to what goes on in a bending mode. Let's try this >>>>>one. You have two bars of equal length with the ends tied together >>>>>with springs of equal length so that, with the springs just pulled >>>>>tight the two bars are parallel, except that one of the springs is >>>>>twice as stiff as the other one. You grab the bars in the middle and >>>>>pull them apart, stretching the springs. The two springs have the >>>>>same load applied to them, but the less stiff one stretches further >>>>>than the stiff one, so the ends of the bars with the less stiff spring >>>>>separate further apart than the ends with the stiffer spring. The >>>>>more you pull the greater the difference becomes, or the two bars are >>>>>rotating away from each other the more you pull. Basically, in order >>>>>to balance the load on the ends of the bar so that they don't spin out >>>>>of your hands the less stiff spring stretches further so the pull on >>>>>the end of the bar is the same as that from the stiffer spring and the >>>>>bars are stationary in your hands but rotated away from each >>>>>other. From a mechanics standpoint the 'moment' (force times >>>>>distance) about the pivot point, the point you are pulling the bars >>>>>apart from, has to balance. Because the distance is the same (you are >>>>>grabbing the bar in the middle), the forces applied to the ends of the >>>>>bar by the springs also have to be equal, but this means that the less >>>>>stiff spring has to be stretched further than the stiff spring so the >>>>>bars separate further on one end than on the other. This is kind of >>>>>your steel and paper table legs, same load but different deflection. >>>>> >>>>>Now lets move the pull point on the bars 1/3 of the length of the bar >>>>>from the stiff spring end, hence two thirds of the length from the >>>>>less stiff spring end, so that the distance from the pull point is >>>>>twice as far from the less stiff spring end than the stiff spring >>>>>end. Now pull the bars apart. The bars will remain parallel because >>>>>the moment about the pivot point from the stiff spring is the same as >>>>>the moment about the pivot from the less stiff spring, and the bars do >>>>>not rotate apart. The deflection in the less stiff spring, which is >>>>>the same as the deflection in the stiff spring, applies the same >>>>>moment to the bar (although half the force) because the distance to >>>>>the pivot (the point you are pulling on) is twice as large (half the >>>>>force times twice the distance). This new pull (or pivot) point is >>>>>the 'neutral axis'. If you could push on the bars they would still >>>>>remain parallel because the 'stiffness' is the same in both directions >>>>>and the forces on the end of the bar are still producing the same >>>>>moment about the pivot point. This is roughly analogous to what goes >>>>>on in a beam with an applied bending load. >>>>> >>>>>See if this helps. If not, I'll be glad to try again. >>>>> >>>>>Regards, >>>>> >>>>>Alan >>>>> >>>>> >>>>> >>>>> >>>>> >>>>>At 10:05 PM 12/28/02 -0500, you wrote: >>>>>>Alan, >>>>>>Thanks for the explanation. It seems to make more sense that >>>>>>way. Question: You have a table or statue or any other object that >>>>>>stands on legs. One leg is made of steel the other is made of >>>>>>paper. It falls over into the leg of paper. Why the paper leg and >>>>>>not the steel leg? I am smart enough to know this is too simple to >>>>>>apply to shafts, so await the dressing down. Is this not similar to >>>>>>the two sides of a shaft? As Dave referred to, it seems intuitively >>>>>>that it would bend in one direction more easily than the other, >>>>>>though in reality it doesn't. I may get out of 9th grade physics yet. >>>>>> >>>>>>Al >>>>>> >>>>>>At 05:18 PM 12/28/2002, you wrote: >>>>>>>In an attempt to understand where the 'weak and strong' sides of a >>>>>>>shaft concept came from it occurs to me that one of the problems >>>>>>>with understanding this concept is that it is easy to visualize a >>>>>>>shaft that is stronger on one side than the other; a thicker wall on >>>>>>>one side in a steel shaft, or more fibers on one side in a composite >>>>>>>shaft. This will, indeed, result in a shaft that is 'stronger' on >>>>>>>that side - to a tensile (or compressive) load applied parallel to >>>>>>>the axis of the shaft! Assuming the shaft remains straight the >>>>>>>strain and stresses in the shaft material will be the same through a >>>>>>>cross section but, because of the greater cross sectional area on >>>>>>>the 'thick' side of the shaft more of the reaction force to the >>>>>>>axial shaft load will be carried on that side of the shaft, so, in a >>>>>>>sense, it is 'stronger'. In a bending situation, however, because >>>>>>>of the redistribution of stresses that occurs in the shaft to >>>>>>>balance the forces on either side of the neutral axis, this does not >>>>>>>result in a shaft being stiffer in one direction than in the >>>>>>>opposite direction. In a given bending plane the shaft has the same >>>>>>>stiffness in both directions. The 'neutral axis' is defined, by the >>>>>>>way, as the line of zero stress through the cross section of a shaft >>>>>>>under bending load and is not always at the geometric center of the >>>>>>>shaft. The stresses in the material on one side of the neutral axis >>>>>>>are compressive and tensile on the other for bending in one >>>>>>>direction and then reverse for bending in the other, but the neutral >>>>>>>axis remains in the same location, hence the resistance to bending >>>>>>>(stiffness) is the same. I hope this helps. >>>>>>> >>>>>>>Regards, >>>>>>> >>>>>>>Alan >>>>>>> >>>>>>> >>>>>>> >>>>>>>At 04:58 PM 12/26/02 -0500, you wrote: >>>>>>>>At 04:32 PM 12/26/02 -0500, Al Taylor wrote: >>>>>>>>>I'm impressed. I have no clue if you answered my question, but I >>>>>>>>>was impressed. John, you still there? ;-) >>>>>>>>>Al >>>>>>>> >>>>>>>>OK, John and Alan and I all said, counterintuitive as it may seem, >>>>>>>>yes it bends exactly the same TOWARD and AWAY FROM the spine, as >>>>>>>>long as it's in the same plane. >>>>>>>> >>>>>>>>You could weld a small steel rod to the shaft, to give it as stiff >>>>>>>>a spine as you want. It will still have exactly the same stiffness >>>>>>>>in BOTH DIRECTIONS in the same plane. >>>>>>>> >>>>>>>>Twirling it in a spine finder might or might not say that. But >>>>>>>>measuring the REAL stiffness will. I have posted here how to >>>>>>>>measure true stiffness, several times over the past week. >>>>>>>> >>>>>>>>Hope this answers it. >>>>>>>>DaveT
