Hi Prof Tutelman. I assumed I'd get a response from you and I appreciate it. As always, reasoned and reasonable. I spent some time today with a couple clubmakers. We discussed this anomaly, if I can call it that. What occurred to me is pretty much what you mentioned re: clamp length. Clamping 2" or 4" or 5" simply measures butt frequency. We all know the butt end of a shaft is, typically if not always, the stiffest part of the shaft. Diameter alone should be obvious enough. So measuring down the shaft - "profiling" should provide much clearer data. The shafts I used, the Aldila filament wound, are significantly um, "stiffer" at about halfway down towards the tip compared to the PC Xtra Lites I replaced them with. What really bugs me about this is that I knew I was measuring butt freq on the Kaufmann meter. That simply didn't occur to me until I began clamping at different locations on the shaft. So now, I have a set of shafts which, if I can find a Godzilla-like member here who needs a reshaft job, I may be able to get rid of them. Otherwise I think I'll epoxy 20 penny nails in the tips and use them to pick up trash around the area. TFlan
> Date: Tue, 3 May 2011 15:22:15 -0400 > From: [email protected] > Subject: RE: ShopTalk: This is a mystery to me . . . > To: [email protected] > > I don't have the answer, but perhaps some suggestions. The two things > that occur to me are: > > (1) Profile: everybody has been talking about this, more in > terms of bend points or frequency measurements at certain > frequencies. But basically it is the profile. > > (2) Torque: more than 20 years ago, Tom Wishon and Jeff > Summitt found that shaft torque factors into the subjective > perception of stiffness, though it has absolutely no effect on the > usual stiffness measures (frequency, EI, deflection). > > There may be other factors as well, but those are the ones that come to mind. > > A few details... > > At 12:48 PM 5/3/2011, Tom Flanagan wrote: > >Measuring from a 5" clamp doesn't tell the whole story, obviously. I > >don't have the wherewithal to profile the shafts other than to try > >different clamp lengths, which I'll probably do next week. > > Clamp length is barely an issue here. The real thing is WHERE you > clamp the shaft along its length. The length of the clamp is a side > issue. Which brings us to... > > > At 01:03 PM 5/3/2011, Allen Humphrey wrote: > >TFlan...one of the measurements some of the AGCP guys make is a > >15-25-35 measurement from tip to butt with a 454g tip weight using a > >strain gauge freq meter.... > > That's a first step in the direction of profiling. It's a three-point > profile, and a reasonable choice of points if you're going to limit > yourself to three. > > The type of electronics and sensor isn't a big deal. The details of > clamping are a big deal. Such as: > * Is the cited measure (15-25-35) the unsupported beam > length or the total length including clamp. > * Length of clamp and assurance of clamp pressure. > > >Perhaps your NF4 does the same thing [ don't have one ] > > Tom doesn't have an NF4. Bernie Baymiller is the one who added that tidbit. > > The NF4 measured deflection, and is a good tool for profile > measurement. And, like a frequency meter, will not pick up on torque > if that happens to be the things causing Tom's problem. > > Cheers! > DaveT > > -- > Shoptalk ** Sponsored by the new Aldila Voodoo. > Learn more at http://aldilavoodoo.com/
