Shaft Orientation Lines

[Popeye64]

 

I see a lot of guys asking how to line up the factory shaft orientation lines. Shafts that are marked have a white line and a red line 90° of each other.

Here is a good read from Robin Arthur.

 

White and Red Lines on the XCaliber Shafts

When the factory does the first QC/QA check for butt frequency (stiffness) they are instructed to find the most stable plane (perfect oscillation) using the Auditor frequency machine (i.e. no "wobbling"/out of plane movement). That plane is then measured and if within the shaft’s specification tolerances (+/- 2/3 cpm), is marked w/ a WHITE line - a "poor man's PURing" if you will. The shaft is then rotated 90 deg. and again checked that it is w/in that shaft’s specification tolerances. It doesn't necessarily have to have "perfect motion", but it's normally pretty close. That plane is then marked w/ a RED line. This step then insures rotational consistency as we don't want a shaft that is very stiff in one plane, then a LOT weaker in another. That may cause out-of-plane bending under load/during a swing – not a good attribute for consistent bending during a golf swing. The WHITE line is then rotated 90 degrees counter-clockwise, or in the ball flight direction for a right-handed golfer. This rotation automatically brings the RED line to the top, or perhaps at 0 degrees. So, now we have the most stable plane aligned to the flight direction of a golf ball. Countless hours of testing has shown…

It WORKS!!!

 

 

 

A Brief Discussion on Frequency Testing

Historically throughout the years, the stiffness of a golf shaft was measured by simply securing the butt end of a shaft (called “cantilever”) and then suspending a weight at the tip end of a shaft and measuring how far it bended (was deflected) - the more deflection, the weaker the shaft. This method of determining shaft stiffness was limited in that it was actually measuring the sum total of all the incremental points of stiffness from tip end to butt end of the shaft. Imagine 2 shafts with the same degree of bend. One shaft could be stiff at both the upper and lower sections, and weak in the middle section. A second shaft could be very weak at the lower section, but stiff in the upper and middle sections. Can you see why these two shafts could play completely different yet have the same deflection?

 

Enter the measurement methodology called frequency. Frequency was originally thought to be a better method of measuring shafts because it was a “dynamic” test – meaning the shaft was “moving” or in this case oscillating up and down. Those cycles were read by an optic sensor and read as “cycles per minute” or CPM. This technique though advanced was still reading the summation of all the incremental stiffness referred to above. To make a long story short, while at Grafalloy I started looking at incremental stiffness along the length of a golf shaft using a test procedure that basically measured what is called EI Curves. To obtain an EI Curve, measurements are taken every 2” for the full length of a shaft. A graph of the stiffness measurements (profile) along the entire length of a shaft could now be visually seen.

 

Back to the 2 shafts above. Although having the same butt stiffness, now we could see and quantify “how” did they arrive at the same deflection or cpm values. Further, the performance of these two shafts could be better understood because of this distribution of stiffness (and the same is true for weight, torque, etc.). Because of the complexity and cost of the testing for EI Curves, Britt and I were members of a Team that established a simpler method call Zone Frequency – an invaluable tool in the design and testing process. It’s like knowing how a car engine works, and what need to be done to make it run even better.

 

 

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[aerospace_ray]

Absolutely concur with your reference data you posted. Very good information. Thanks for posting this.