Hi Dave, Let me jump in here and add my opinion to one aspect of your reply. let me first say that Bernie has contacted me to let me know that he sent that message to the Shoptalk group by mistake. He meant to send it directly to Reed, but hit send before he changed the address.
See my comments below. I hope they make some sense. Dan Neubecker [EMAIL PROTECTED] > -----Original Message----- > From: Dave Tutelman [mailto:[EMAIL PROTECTED]] > Sent: Monday, December 23, 2002 10:04 AM > To: [EMAIL PROTECTED]; [EMAIL PROTECTED] > Subject: Re: ShopTalk: shaft flex v.s. frequency > > > Reed, > Just so you can get a somewhat balanced view... > > Bernie is retired from advertising. > I'm a retired engineer and researcher. > > When Bernie describes something he likes, it's a > full-court-press sales pitch. > When I describe something (I like or dislike) I can't bring > myself not to > present the other side as well. > > I am involved in the NeuFinder effort, and will be building one this > winter, so I'm certainly a fan. But I feel Bernie's sales > pitch leaves > another side to be told. > > First of all, he answered the questions you asked ("how do I > get one or how > do I build one?") but not the underlying "what is it?" It is > a deflection > board, with the following bonuses: > (a) Readout on Dial Indicator, so you don't have to do major visual > interpretation to do the reading. > (b) Dan & Bernie have pioneered a way to use it to match a > set of shafts > for building a set of clubs. The matching is much faster and > at least as > accurate as frequency matching -- possibly more accurate. > (c) Detailed plans are available to build it. > > My involvement in the effort is to help solve two shortcomings it has > compared with the frequency meter approach: > > (1) Set up a calibration procedure and/or tolerance control > so readings > from one NF2 will be the same as for any other [calibrated] > NF2 for a given > shaft. This is not a problem when matching shafts, but it is > when talking > with other NF2 owners about the stiffness of shafts. Which > brings us to... > > (2) Relate NF2 reading to frequency. This is necessary > because frequency > is the current lingua franca of clubmakers. The catalogs of > some of my > favorite shaft manufacturers provide frequency numbers. The > DSFI tables > provide frequency numbers. I know my own clubs by their > frequency numbers. > Etc etc etc. We need to be able to cross-reference with > NeuFinder readings. > > I also have some problems with Bernie's statements about > spines. A couple > of days ago, Bernie and I agreed that we both believed in > John Kaufman's > statments about spines in his tech notes. Apparently we > didn't agree on all > of them. You can see them at http://www.csfa.com/techframe.htm. Pay > particular attention to the note on "Inverted flex board"; > that has John's > more rigorous and quantitative explanations -- and the important > conclusions which are the ones I said I agree with. Here's a > copy of those > conclusions: > > BEGIN QUOTE___________ > Here's a summary of what I think about spines and stuff. (I > could be all > full of beans of course.) > * In a spine finder a bent shaft will react just as a shaft with > variable stiffness. > * Steel and filament wound shafts may be bent and react > in a spine > finder but their true stiffness is very uniform. > * The strong and weak axes are always 90° apart. > * A shaft has two weak axes 180° apart and two strong > axes also 180° > apart. See the "bow-tie" in Plot 2. > * I think one of the weak axes should be pointed at the target. > * The weak and soft axes can be found with a frequency > analyzer and are > the non-wobbling low and high frequency positions. > * The better the shaft the less important is spine aligning. > * Every shaft has two natural frequencies that are always > 90° apart. In > good shafts these two frequencies are very close, 1 or 2 cpms. > END QUOTE__________ > > A couple of specific comments on Bernie's points... > > At 07:07 AM 12/23/02 -0500, Bernie Baymiller wrote: > >With a frequency analyzer, you > >have to locate the NBPs and spines on every shaft in a > spinefinder first, > >then frequency match and as you tip trim, the spine location > can move and > >you have to re-spine the shafts again. > > Simply not true! > If you believe JK's tech notes, you get a more accurate spine > location from > the frequency meter. If you use a spine finder, you can only > consider it a > starting point, to save you some time finding the REAL spine with the > frequency meter. Dave, I may disagree with you here depending on what you aspect you believe is "simply not true". It may depend on how you define "spine". What we are really trying to find is the plane the shaft most wants to bend in or the NBP. It is a combination of flex and shaft geometry that determines this, not flex alone, IMO. I can attest that I've had many shafts where the spine/NBP location does in fact change in the bearing finder as it's position, relative to the bearings, changes. I can't say if this is a change in stiffness or rather a change in shaft geometry, but I have observed this many times. For example, let's say a shaft is out of round for a portion of the butt and/or tip. As this shaft is placed in a bearing finder, the bearings will react to this geometric difference, and place the shaft in the orientation with the least resistance to bending. If this difference is not consistent along the length of the shaft and the shaft is placed in the finder such that this anomaly is avoided by the bearings, then the finder will react accordingly and find a different low resistance plane, hence the NBP/spine will move. Again this may not be stiffness related, but it certainly could be. Even if it's strictly a reaction to a shaft's geometric irregularities, I would argue that this these irregularities are just as important or more important a matching consideration as stiffness, since they directly effect how the shaft will "prefer" to bend when under flex. With a frequency analyzer, it seems to me, all you can be sure of is the frequency you get, not whether it reflects how the shaft is likely to react to bending. In addition, most frequency analyzers are optical and must be plucked in one plane to get an accurate reading, otherwise the optics can't pick up the shaft movement. This is a major drawback, IMO, when analyzing a shaft with geometric irregularities, which include most shafts. If you aren't reading an irregular shaft on a FLO plane, you can have severe wobble. I would argue that, with significant wobble, you do not receive an accurate flex reading, since the optics can't read both the up and down and back and forth readings. A severe wobbler, might make a number of cycles in the direction opposite of it's plucking, so that the optics don't see any cycles at all. As you know, I'm not an engineer, but I believe using frequency readings alone, with the goal of orienting shafts to weaker or "preferred" bending planes only looks at one aspect of what should be considered. It almost completely ignores the very important consideration of local geometric irregularities. It's these local geometric irregularities that can determine what plane a shaft will "prefer" to bend in. How about this scenario. You use a bearing finder and mark the NBP/Spine at full shaft length to get you close to the FLO planes. You put it in your frequency analyzer and tweak it to find FLO. You read the frequency at FLO and having tested for the tip trimming sensitivity, you determine you need to trim around 4" off the tip to get you close to your target frequency. You trim the tip and it turns out there was an irregularity trimmed out and it no longer FLO's. Is your frequency reading at that point valid or accurate? How much wobble is ok until it is not accurate? Do you have to rotate the shaft back into a FLO condition to get a valid reading of flex? If so, might that change your frequency reading as well? Wouldn't you have to re-check this shaft for spine/NBP location if you want to be sure you are reading frequency along the "preferred" bending plane. We've had reports from numerous clubmakers that have indicated that the spine or FLO has changed with trimming of the tip. My guess is that it's probably due to an irregularity being removed with tip trimming or one coming into play in the butt area that did not show up in the untrimmed spine or frequency testing. > > >The dial indicator also can tell you > >the exact magnitude of the NBP-S1, simply by rotating the > shaft and watching > >the dial indicator. > > That is mostly true, and it is a significant advantage over > most spine > finders. > > I say "mostly" because, like all mechanical spine finders, it > can still be > spoofed by geometric, rather than stiffness, imperfections in > the shaft. > Again, see JK's notes for more detail. > > >You have to unclamp and reclamp the shaft in a frequency > >analyzer to do the same operation. > > Definitely true. > > But if mechanical spine finders (including the NF2) worked > properly -- that > is, they found true spine stiffness rather than a combination > of spine and > geometry -- they would have as time-consuming a process. > Again, see JK's > note on inverted flex board for the proper way to determine spine. > > Hope this helps. > DaveT > >
