-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]On
Behalf Of Corey Bailey
Sent: Tuesday, March 04, 2003 1:56
AM
To: [EMAIL PROTECTED]
Subject: RE: ShopTalk: Harrison
Spineless Technology
Alan:
Indeed, Pat Kelly’s comment regarding the direction of shaft loading is
correct and your “Fun Experiment” supports that. However, neither
addresses the potential for the random location of a predominant spine to
affect the unloading of the shaft during the downswing. In fact your fun
experiment, while an interesting demonstration in one of the laws of physics,
actually supports the claims of those of us who go to the trouble to align
shafts in the first place.
Here’s why:
Let’s use the premise of your experiment only add the variable of a
prominent spine in the shaft being used for the demonstration. I would also
suggest that the shaft under test be secured in a device that can be precisely
rotated. Clamped in the chuck of a machinists lathe for example. Having located
and marked the spine on the shaft, you can now observe any influence on the
oscillation plane of the shaft as you rotate the shaft in a fixed position.
What you will find is that as the shaft is oscillating (having been twanged in
a vertical or horizontal plane) and you rotate it, you will force a momentary
wobble in the oscillation plane. Or: momentarily forcing a flat oscillation
plane onto an oval. Naturally, the oscillation plane will return to the
original state after a few cycles (wobbles) demonstrating “conservation
of momentum.”
For example:
We have marked the spine on a shaft and we mount it in the lathe chuck with the
spine located at 9 O’clock. When the shaft is twanged in a vertical plane
and rotated clockwise, a momentary oval will occur in the direction of
rotation. The same will happen when the shaft is rotated counter-clockwise.
So indeed, the spine, if prominent enough, can have a momentary affect on the
unloading of the shaft. If you were to use a shaft with prominent spines 180
degrees apart (us "spine geeks" refer to this as a type 2 shaft) you
would be able to easily see the effect. Type 2 shafts tend to behave more like
a Venetian blind when it comes to bending in line with NBP or against the
spines.
One really does not have to go to all this trouble to see the influence of
manufacturing anomalies on the bending properties of a golf shaft. Simply
locate the spine(s), clamp the shaft at the butt end, twang it, and observe the
oscillations. The oscillation plane will start out in a straight line and wind
up as an oval. As you rotate the shaft, clamp it, and repeat the procedure, you
will be able to observe the oscillation patterns change and finally, you will
find an orientation where the oscillation stays in a flat line. Clearly,
something in the make up of that shaft is affecting (or not) the oscillation
plane.
Yeah, yeah, I know, you are going to say that the shaft is not rotated enough
or loaded and unloaded long enough during the downswing (about a half cycle) to
make a difference. And you ask: “where’s the empirical
evidence?”
It exists in the notes of all of us shade-tree mechanics that have been
experimenting in our shops over the years. It exists in the satisfied customers
who know full well how much more playable their set is after having been
aligned by us fringe scientists. It exists in the 80% of the touring professionals
who have had their equipment carefully aligned and assembled by the OEM’s
clubmakers who still deny that their custom clubmakers are building shaft
aligned clubs for their sponsored athletes.
Pat Kelly is also correct in his assumption that what us spiners are typically
measuring on steel shafts is bend. I refer to it as residual bend and I do
have the data to support that notion.
FWIW, I would also be interested as to why the “pro builders” are
aligning S1 at 6. This tends to run counter to the findings of us “spine
geeks.”
Lastly,
While I love working with type two graphite shafts, I can't wait for spineless
shafts. It will speed up my assembly process and allow for all clubs to be
built with the shaft label up. And…… all of this discussion started
with graphite shafts. There’s no such thing as a spineless steel shaft
and probably won't be in our lifetime.
CB
BTW,
Being convinced that “the only thing
you find with a support-the-shaft-in-bearings-and-hang-a-weight-from-it spine
finder is bend (curvature) in the shaft, steel or graphite.”
Have you experimented much with a bearing finder?
At 04:03 PM 3/2/03 -0500, you wrote:
. . . Now, when the shaft is unloaded, it moves in the
DEFLECTED
direction that it was loaded in, not exactly on the swing plane line. If
this coincidentally works, great, but it IS COINCIDENCE, not science.
Here is a fun experiment that demonstrates this effect. Put a tip weight
on a bare shaft (no grip) and hold about a foot of the butt down on a hard
surface with the rest of the shaft hanging over the edge. Twang the
tip into a vertical oscillation plane and slowly roll the butt of the shaft
over the counter top. Bet your friends whether the plane of oscillation
will roll with the shaft or stay vertical. It will stay vertical, and it
is science; it's conservation of momentum. Use a tip weight because the
offset mass of a club head will cause the shaft to do strange things - it
basically stays in the vertical plane but it will do some funny oscillations.
The same flawed arguement works for 6-12 alignment of
the N plane. Although
the shaft is loaded in a neutral plane (and therefore deflection and twist
are minimized), it unloads in a spine plane. So, the spine has a chance
to
deflect/twist the shaft as it unloads.
All this said, the common answer from the guys who put shafts in tour
players' clubs that I've spoken with is to use shafts that don't exibit a
spine effect. With irons they tend to align S1 (I've been
educated/convinced that S1 in steel is bend, not spine) at 6, FWIW.
I'm convinced that the only thing you find with a
support-the-shaft-in-bearings-and-hang-a-weight-from-it spine finder is bend
(curvature) in the shaft, steel or graphite.
But I am really responding because I am curious why they align at 6? Have
they found that it makes a difference or is this a
we're-not-sure-so-let's-do-it-the-same-way-every-time thing? I've pretty
well convinced myself that it can't make much difference (for small curvatures,
less than a couple of millimetres) so I'd be curious if they have reason to
believe that it does.
Thanks,
Alan Brooks
