Dave T.
First, thanks much for taking the time and expending the energy to
respond so completely to my sophomoric question!
There clearly appears to be some strongly held divergent opinions and
theories, regarding residual bends, placement of spines, COG,
etc............! Thanks to you and all that entered the fray, I now know
more about these things than I care to know, but still don't know enough!
Like the scholar that returned from a 2 year sabbatical when asked what he
had learned said: "The only thing I can say with certainty is that I am
absolutely, totally confused, but at a significantly higher level!!!!!!
Again thanks all; I will eventually figure it out; hope ya'll do too!!!
----- Original Message -----
From: "Dave Tutelman" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>
Sent: Thursday, October 09, 2003 4:23 PM
Subject: Re: ShopTalk: NBP-COG
> At 12:48 PM 10/9/03 -0500, Bill Douglas wrote:
> >Gentlepersons,
> > I have been lurking on this NBP-COG "Fest" and lacing the level of
> >technical acumen the protagonists and antagonists possess have become
> >totally confused! However, its too juicy to not dive in; so here's at
it!
> >
> > I read some time ago that Golfsmith did some experimenting/testing
with
> >the Spine/Cog alignment and found there was no appreciable/discernable
> >difference in shaft performance vs. Spine at one of the 4 cardinal
> >positions. Also if I'm not mistaken, John Kaufman got confirming results
> >when he did similar experimenting/testing. Is this the same thing that's
> >being discussed in this case? Please advise. Thanks in advance!!
>
> Bill,
> You're right, it is confusing. In fact, lots of the people in the
> discussion are confused, because we can't all be right when we're saying
> such different things. Anyway, let me give you my take on it. If I'm wrong
> (of course I doubt that, but there are others who are SURE I am -- who
> knows?), then this will be further confusing.
>
> First of all, we are talking about spine alignment or NBP alignment. Leave
> COG out of it for a while, until we understand spine and NBP.
>
> SPINE is the stiffest plane of a shaft in bending. NBP is the most
flexible
> plane. The concept of plane is the first area of disagreement among the
> protagonists. Some say that it is possible for the stiff side to be 180*
> opposite the flexy side. But the engineers in the group say that is not
so;
> it is an artifact of an imperfect instrument used to find the spine. In
> fact, spines will be 180* apart every time, hence I talk about "plane".
> Similarly NBPs will be 180* apart from one another every time. BTW, that
is
> what John Kaufman proved. He proved nothing about how to align the spine
or
> NBP when you make a club, just that the order of things as you go around
> the shaft is spine-NBP-spine-NBP at about 90* intervals. This also agrees
with:
> * Theory that every mechanical and structural engineer learns in school.
> * Tests that others have done, including one I've witnessed involving a
> FlexMaster.
>
> There is another issue here: the residual bend in the shaft. That is, no
> shaft is perfectly straight. Some are straighter than others. Any lack of
> straightness will "fool" the simple spine finder. There are more accurate
> ways of finding/measuring the spine that are not fooled by lack of
> straightness. Dan Neubecker (inventor of the NeuFinder, which is fooled)
> takes the position that you should orient what you find in the NeuFinder,
> because bend affects performance in the same way that spine does. I don't
> believe any such thing. Oh, it might coincidentally be true, though I
doubt
> it. But there is no evidence to support it -- and two of the three
theories
> of spine alignment (the two credible ones, IMHO) say that's not even
close.
>
> OK, now we have talked about characterizing the shaft. Let's talk about
how
> we align shafts in clubs. I'll assume the shafts are straight, so that
> spine is the only alignment issue. There are three competing assertions
> about how to orient the spine:
>
> (1) Spine in the target line, NBP in the heel-toe plane. That is
> essentially what Weiss advocates. (He talks about the FLO. But if you find
> the REAL spine, then the higher-frequency FLO is exactly the spine.)
>
> (2) NBP in the target line, spine in the heel-toe plane. Most members of
> this forum believe in this orientation. It seems to make the most sense to
> me; no quarrel with the forum here. It also happens to be what Talamonti
> advocates.
>
> (3) NBP oriented toward the center of gravity (COG in the forum, CG
> traditionally). This is a brand new proposal from Tom Wishon. I've already
> posted my explanation of the theory behind it. Is this a more important
> effect than #1 and #2? I don't know. I don't think Tom does either yet.
But
> people are trying it out. None of the tests I've seen were controlled
> experiments, just "I built a set of irons this way and they work well." So
> far, returns are favorable. I don't know if that means much, given that
> most of the reports I've seen so far involve shafts with very little spine
> -- so orienting them any way at all might give fairly similar results.
>
> Let's get back to your statement, "there was no appreciable/discernable
> difference in shaft performance vs. Spine at one of the 4 cardinal
> positions". That says that orientations #1 and #2 are both good enough
that
> it's hard to tell the difference between them. I'm quite prepared to
> believe this. I hope to find out soon.
>
> Anyway, there are lots of interesting questions about spine alignment
where
> people are taking positions but there is either no data or no
strong-enough
> data to either support or refute those positions. Here are a few:
>
> * Obviously, which orientation is "best": #1, #2, or #3 above, or maybe
a
> different one altogether.
>
> * How much difference does it make? There are tests that have been done
> to determine this, but the results are commercial secrets; at least Weiss
> and Talamonti have done testing, and I'd be surprised if others haven't as
> well.
>
> * How big does the spine have to be to make a difference? I hope to
> answer that question before too long. If there is a spine size below which
> it orientation does not matter, and if there are manufacturers producing
> shafts below that number at reasonable prices, then my strategy would be
to
> buy those shafts and not bother with alignment.
>
> * How does lack of shaft straightness affect performance, and -- if it
> does -- how should residual bend be oriented to minimize problems? If Dan
> happens to be right about that, then simple spine finders are perfectly
> useful tools; if not, then they are flawed.
>
> * Does a well-oriented shaft with a large spine give better or worse
> performance than a shaft with very little spine? Some folks believe it
> gives better performance; this is called the "supershaft" theory. These
> clubmakers set aside the shafts with the biggest spines and save them for
> their own clubs, or charge customers a premium.
>
> These are the most interesting questions to me, but I'm sure there are
> others out there as well. They can only be answered by well-designed tests
> or by a good, valid, quantitative theory of how the club performs with
> varying spine orientation. As I've said, I've seen three such theories.
> Well, two that are quantitative, and one that is mostly hand-waving. Maybe
> this winter I'll try to simulate them on the computer and see if the
> results seem to agree with our collective experience and the few known
test
> results out there.
>
> Hope this helps rather than confuses.
>
> Cheers!
> DaveT
>
>
>
>
