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.