Tedd/Tim : The trick to using frequency as a means to measure the bend profile of a shaft does indeed have variations which one has to be able to identify as significant or not within each area of the shaft. Over the years of working with our current means of measuring the frequency of shafts at the beam lengths of 41", 36", 31", 26", 21", 16" and 11" with a 454 gram tip weight, we have found that as the beam length shortens, the range in frequency among multiple units of the same shaft is automatically going to spread.
The main reason this happens is simply because of the much higher CPM rate for the shorter beam lengths combined with the counting methodology of the analyzer being used. So one of the things we do to get a much better feel for whether the range we're seeing at the short beam lengths is real or not is to measure the OD of the shafts at each beam length clamping point. Given the fact that the mandrel used to make the ID for any graphite shaft is completely consistent (from the better shaft makers it definitely will be spot on with a +/-0.0005 inch tolerance) that means the main point of error will be seen in the OD from shaft to shaft of the same model/flex, which comes from sanding the shaft after it is rolled and baked. After checking thousands of shafts which included as many as 10-20 pcs of the same model/flex from all sorts of shaft makers, we have found that when you see a variation in the OD at any beam length within units the same model/flex that is 0.002" to 0.003", that is VERY GOOD sanding quality. When you see the range run up to a variation of 0.005" and higher, here is when you start to really see CPM variations that would indicate a variation in the bend profile that a VERY GOOD ball striker could detect. At a 0.010" variation in the same beam length point of measurement among shafts of the same model/flex, that becomes large enough that an average ball striker with lots of ball hitting experience can note the difference in feel and indicative of less than stellar quality control over the sanding of the shafts by the shaft maker. So in translating this back to the CPM readings for the different beam lengths from 41" down to 11", we have been able to identify what type of CPM variance among multiple shafts of the same model/flex is significant in terms of enough variation to account for bending or feel differences in the shaft for golfers who have the ability to detect such differences. IN the butt end, where the beam lengths of 41" and 36" control the measurement, this one is easy because so many Clubmakers have the experience of performing basic butt end frequency readings. Here, when you have a variation of 10-12cpm, you are looking at a difference of a FULL FLEX, as you know. Variations in the butt that are 2cpm and lower indicates a very good quality shaft production standard. 3-4cpm are not likely to be detected by any but the best ball strikers, but anything over 4cpm is not that great. In the center area of the shaft, which is indicated by the beam length measurements of 31", 26" and 21", because the CPM readings now are high enough to start messing a little with the repeatability of even the best frequency analyzers, it takes a separation of 20-25cpm to equal the same relative FULL FLEX difference seen in a 10-12cpm difference in the butt section measurements. Thus in the center areas when you have multiple units of the same model/flex of shaft that are 4-6cpm off from each other, this really is insignificant with respect to shaft inconsistency. Only when the center area of the shaft starts to show a 7-10 cpm spread among units of the same model/flex does it start to indicate a difference that could be detected by good to decent ball strikers. Down at the tip section, which is indicated by the beam length measurements of 21", 16" and 11", here you can definitely see wide variations from "twang" to "twang" of the same shaft because of the analyzer's counting methodology. When we do the short beam length tests in our work, we will often "twang" the shaft 10-12 times, then re-clamp and do it again before we start to identify just what IS the CPM reading for these very short beam lengths, and correspondingly high CPM measurements. Down in the tip, we now feel (and concurred by John Oldenburg, VP of R&D of Aldila) that what is a difference of 10-12cpm in the butt and 20-25cpm in the center is now 40-50cpm in the tip section measurements. Thus it takes a 40cpm difference between the tip measurements of two shafts to indicate something close to a FULL FLEX difference. And from that, when you see a 10-14cpm difference in the tip section measurements, that really is imperceptible to all but the very best ball strikers. Tip section CPM differences have to be in the area of 20+ cpm and more before any signficiant segment of golfers would ever start to feel any difference in hitting shots. Granted, I do believe that in the long run, electronic deflection would be a better way to do bend profile analysis because of the difficulty in making the counting protocol of a good frequency analyzer to be able to be a little more repeatable for short beam length measurements. But since virtually no Clubmakers own a proper electronic deflection machine, this sort of makes bend profile analysis impossible for each clubmaker who is interested to do on his/her own. Thus for now, I plan to stay with CPM bend profile measurement because it becomes a little more possible for more Clubmakers with their FQ analyzers to participate themselves. But if this gets to be more and more difficult to wrap our arms around, we may have to make the switch some day to deflection. IN the meantime, hope this helps a little, TOM WISHON -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Childers, Tedd A Sent: Monday, November 06, 2006 10:39 AM To: ShopTalk@mail.msen.com Subject: RE: ShopTalk: Shaft Profiling Discussion EXCELLENT post John. I have not gotten into shaft profiling for this very reason, as I have not seen enough data out there to convince me that the profile is consistent from shaft to shaft on the same brand/model of shaft. Quite a few people have profiled single shafts, but no one (except Tim apparently) has systematically tested the "same" shaft (i.e many of the same brand/model) many times to see if there is a consistent profile. Tedd -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Monday, November 06, 2006 9:54 AM To: shoptalk@mail.msen.com Subject: ShopTalk: Shaft Profiling Discussion Hi Gang: Thought this might get the juices flowing early Monday morning. I noticed a post at another discussion group by Tim of MyOstrich that seemed to say that profiling can be troublesome without a very large sample size for some manufacturers. Have any of you also noticed this? Tim's post is below. He hangs out here every so often (may be off this week on a SMT trip, though). Here's Tim's post: As you get more and more into profiling, you'll also find that there are shafts with identical bend profiles that feel and play nothing like one another... It's a fun part of trying to understand the golf shaft. There is one problem with the data set - at least the last time I saw it - shafts are profiled in very small "sets" and generally from the same run from the manufacturer. I have 50 different shafts profiled in the same model and flex from a very well known shaft company. These shafts were purchased from different sources, a just a few at a time. They profile into nearly 6 different shafts - very, VERY different shaft profiles. You can't even average them, and the profile in the database is not really representative of the shafts that I have either. Consistency or a very large sample size are needed to get a picture of how weak or poor a shaft profile may be as a representation of a particular shaft model and flex. -- Thanks! John Muir shoptalk 810.923.7396 http://clubmaker-online.com http://gripscience.com http://elevongolf.com
