While the top-quality shaft makers do manufacture shafts with very high accuracy and consistency, there are shafts in the golf industry that possess a variation in the consistency of the stiffness about their circumference. If severe enough, these inconsistencies can cause mis-direction problems when the shaft is installed in such a way that those inconsistencies get in the way of the required bending of the shaft. When shafts are identified to be inconsistent in their stiffness, they are said to have a "spine."
Therefore, the practice of "spining" is offered by some custom clubmakers. Spining involves, first, locating the most consistent bending position of the shaft; and second, installing (or re-installing in already finished clubs) the shaft so that its most consistent bending position is pointing directly toward or directly away from the target line.
Today, many shaft makers pre-test their shafts to locate a consistent plane of bending in the shaft, and only then paint and apply the name/logo to the shafts. Thus, with the vast majority of quality shafts made today, there is little need to have the shafts checked for spine location and re-installed in the clubheads.
