Spine definition

[Chieflongtee]

How would define a spine in a golf club? Simply put a poorly made shaft has usually 2 planes 90* to each other. One plane is stiffer than the other. When one plane has 10 more cycles per minute than the other it means one full flex difference between the 2. To make it easy to understand let's take a ruler as an example. Hold a 36 or 48 inch ruler (wood or metal does not matter)as you would hold a golf club with the flat(thin) side in the 12 o'clock position. Waggle the ruler and it will flex towards the target. The flexible part is called the NBP short for neutral bend point. The thin side is called the spine. If you were to rotate the ruler 90 degres and perform the same exercise you would barely get the ruler to flex towards the target.
There is hardly any spine in a steel shaft and it's not worth aligning them. Unless you're a believer in residual bend(warped shaft) a steel shaft will never have more than a 1-2 cpm when rotated in a frequency meter 360 degrees. Big waste of time if you ask me.
Graphite shafts are different. Of course some shafts are excellent and don't need to be spined as the frequency is the same all the way around the circumference. Mercury shafts and SK Fiber shafts come to mind and they are guaranteed +- cpm by the manufacturer. There are others out there. Most filament shafts are spineless and are very stable.
Do you need a frequency meter or a NF2 or NF4 to find out if your shafts are properly aligned. The answer is no. But you do have to have a solid vise and an excellent clamp. all you have to do is to clamp the but end of the club and twang it either vertically or horizontally. If the shaft goes straight up and down then the club is properly aligned or is at least stable in 1 of the 2 planes. If it wobbles then it needs to be reoriented.
Hope this unconfuses.

[Kona Golf]

Interesting link on Spines!

http://www.clubmaker-online.com/spines.html

Jim

[Chieflongtee]

Interesting Jim but it's an old article and although most of it is true there is no way that a NBP is 180* in a steel shaft. It is a residual bend. Dave Tutelman calls it feel finding and it is not a true stiffness differiential. There is even a claim in there about a shaft having 3 spines. . . Not perfectly round maybe but 3 spines no way. Try it for yourself. Put a steel shaft in your NF2 and find one that will give you some resistance or a higher reading on your dial indicator. Now take it out and look down the shaft. You will notice a curve or a warp in the shaft. It is pretty much similar to the old technique of rolling the shafts on a flat surface and picking out the straight ones.Now conduct the same experiment in your frequency meter. Clamp the shaft and take lots of readings by slowly rotating the shaft. You'll never find a steel shaft with more than a 1-2 cpm difference.

Got the following from John Kaufman's website:www.csfa.com
Wobble



NOTE 3: If you get into the hairiest of mathematics you'll find any shaft has two natural frequencies and they are always located 90 degrees apart on the shaft. At one point you will get one of these frequencies and by rotating the shaft 90 degrees you'll get the other. If the shaft is flexed anywhere in between both frequencies will be excited and the two will beat against one another causing the shaft to wobble. The two frequencies in a steel shaft or a filament wound graphite shaft are generally very close such that very little wobble will occur. In wrapped graphite shafts this is not always the case due to the seam and wobbling can be pretty wild. I've seen as much as 12-cpm difference between these two frequencies in some shafts. If a shaft is regular along one axis and stiff along the other how do you install it in the club? It's best to buy good shafts. Again the frequency analyzer is a great quality control device. By the way, that vibratory gyro I mentioned in an earlier Tech Note had its two natural frequencies matched to a small fraction of a part per billion. Like I said it wasn't a cheap device.

[Chieflongtee]

The NF4 is a much better device than the NF2 as it takes out residual bend or shaft assymetries out of the equation. When a steel shaft is inserted in the NF2-NF4 if it has a bend it will automatically rotate or snap to a neutral position. The NF4 will take this under consideration as it has a preload setting which takes out factors such as steps and bends. Then the scale is tared to 0 and then it is loaded from that position. In other words NF4 readings are not affected by assymetries.

My english being what it is I have copied below a post from Dan Neubecker(the NF4 founder) which clearly explains what I mean

Quote:


Two words, differential deflection. Here is the problem with the NF2.
It's readings are dependent on the shape of the shaft. For example, it
you were to cut a shaft in half lengthwise and look at it from the side,
you would a taper, maybe several, maybe some steps, etc,., at one time
maybe a bulge or two. The NF2 cannot take these changes into account
from one reading to the next, because it just reads total deflection
caused by that shaft. To exaggerate it for clarity, say you have a
shaft that has a .60" butt but a bulge below the grip that was 1.6"
across. If you were to take a reading with the middle bearings sitting
just before a big hump in the shaft, and then move onto the hump area
with the bearings, you readings will increase substantially. The NF2 is
reading extra deflection because the hump on the middle bearing has
caused the tip to raise up and additional 1" and the tip will therefore
be deflected an extra 1" to get it under the tip bearing. The same
happens with a step, with a quick taper, with a grip, or even with some
grip tape. Just before the bearings drop across a step and just after,
can give you somewhat skewed readings.

The NF4, on the other hand, uses differential deflection to take all
readings. This means that you move the shaft to the position you want
to take a reading at, you deflect the shaft a preloaded amount, you tare
or zero the scale, and then you deflect the shaft an additional amount
to get the final reading. This process ensures that cross-sectional
changes in the shaft, and anomalies, such as a bent shaft, or a piece of
grip tape, the grip itself, or even the hosel of the club, is taken out
of the equation and doe not effect the final reading. Now, the softness
of a grip might have some effect, but the effect of a change in
thickness will not.

In fact, you can read a completed club with the grip under the rear
bearings and the hosel under the front bearings, and get accurate
readings. This means you can even profile a completed club pretty
accurately! All you have to be able to do is estimate how deep the tip
is in the hosel, and place the club in the NF4 so that the hosel is
positioned so that the tip inside would be at the tip stop. I do this
by measuring back from the top of the hosel to the tip stop when placing
the shaft. If I know the tip is 1.25" deep, then I set the club up so
that the top of the hosel is 1.25" back from the tip stop and I do this
at each beam length and profile reading. I tested this in once case. I
took a set of profile readings with the completed club. I then pulled
the shaft and took another set of readings without the head and the tip
against the tip stop (the grips were still on in both cases) and the
readings were within +-.04kg, which would be in the range of 1cpm or so.

Dan
Quote

[Chieflongtee]

Quote:

-------------------------------------------------------------------------------
An independent study on spine aligning was undertaken by Golf Science Consultants, Inc. The study was performed by J. Howard Butler, President of Golf Science Consultants, Inc., and former vice-president of shaft technology at True Temper.

Preliminary test results clearly indicate that when the golf shaft is properly aligned the club becomes more stable, thus improving the impact repeatability (hitting the sweet spot more often).


So far it has only been proven that spining improves impact repeatability i.e on centre hits. Spining is not the holy grail that people would like to believe. You are not going to start drawing the ball all the sudden because the the spine was placed in a specific position.(although illegal) Spining a shaft(when it needs to be spined) will only provide the golfer a better tool. Everything else is up to the golfer.

[Big Johnny69]

I'm well aware that spining won't change your ball flight (draw,fade) but if spining improves repeatability than that would be why my dispersion is tighter. So if that is the case then I am becoming a believer of spining.

[Chieflongtee]

Only on certain shafts Geoff. Earlier this year I got my hands on a MAS shaft. I put it in the frequency meter and twanged it. Sever wobble. So bad of a wobble that the head hit the sensors. It turns out that there was a 12 cpm differential between the spine and NBP. One full flex difference. After reorienting the shaft in it's proper position and retwanging it then the wobble was gone and the shaft oscillated straight up and down. That is the way it should have been aligned in the first place. But that does not happen because it would be too costly and slow down production big time. Does that mean that all MAs shafts are similar. Not necessarily but this particular did have a large spine differiential. SK Fiber and Mercury shafts are all guaranteed +- one cpm. Excelsior shafts are excellent as well spinewise. I am sure there are other excellent spineless shafts out there but I have limited funds and time. Oh how I wish I could spend a day in Golfworks warehouse and test all their shafts.

[Chieflongtee]

If you are interested in the topic check out Chuck Silco Jr's spin indexer.

http://home.att.net/~flo-fixture/wsb...ID-727851.html

http://home.att.net/~flo-fixture/wsb...ID-727856.html

The main purpose of the SpinIndexer,
is so you can clamp ( only once ) an ungripped shaft with clubhead attached and rotate the shaft in increments
In this link, you can see the back of the indexing faceplate which has 36 holes for index rotation of the shaft
http://home.att.net/~flo-fixture/wsb...ID-727849.html


http://home.att.net/~flo-fixture/wsb...ID-727849.html

[Chieflongtee]

Check out this video. It explains it all.

http://www.horsepowergolf.com/VideoSpineFrequency.asp