Abstract: An apparatus for locating the spine of a golf club shaft and performing dynamic stiffness measurements on the golf club shaft includes a clamp assembly and a flexing assembly. Both assemblies are mounted on a common frame and distanced from each other to allow the clamp assembly to operate on one end of the golf club shaft and the flexing assembly to operate on the other end. The clamp assembly includes two collets having six pins per collet to clamp the shaft. A mechanism to rotate the clamped shaft about its axis is provided. The flexing assembly includes a robotic hand to deflect and release the free end of the shaft. A force gage is provided to measure. the force required to deflect the shaft. A photo eye is included in the flexing assembly to measure the oscillation frequency of a shaft that has been deflected and released.

Abstract: A club shaft for a golf club and method for making a club shaft for a golf club are provided herein. The club shaft includes a shaft butt section, a shaft tip section and a shaft intermediate section which connects the shaft butt section to the shaft tip section. The shaft intermediate section includes a shaft outer diameter which tapers from the shaft butt section to the shaft tip section. Uniquely, the amount of taper varies along the shaft intermediate section to avoid any abrupt transitions in the club shaft. The resulting club shaft has a continuous, smooth geometry, without stress concentration areas. This improves the strength, fatigue and fracture toughness of the club shaft. Further, the amount of taper can be specifically tailored to obtain a club shaft having the desired moment of inertia, resistance to torsion, mass distribution, flexure, frequency, strength, and stiffness properties.

Abstract: A shaft for a golf club includes a main shaft, a ring shaft and a flex shaft which are mounted onto the distal end of the main shaft, and a sleeve which may be used to cover the ring shaft portion and the flex shaft portion. Each portion of the shaft is made of a material that is specifically selected for its particular modulus of elasticity, and the modulus of each portion is selected relative to the moduli of the other portions. For the present invention, the ring shaft portion has the highest modulus of elasticity, and the flex shaft portion has the lowest. With this combination, a club head is affixed to the extreme distal end of the main shaft, and a grip is attached to the proximal end of the main shaft portion.