How about shaft concentricity problems where the hole in the center of the shaft is offset a bit from center, resulting in different shaft wall thickness around the shaft. I'm sure you are aware that they can be slightly out of round, even if only for a portion of the shaft...
Dan,
That manifests itself as a difference in flexibility, or pure spine. It will show up in a Neufinder, but will also show as FLO, and will show from differential deflection measurement.
What I was talking about when I said "out of round" -- and what, I assume, Alan meant as well -- was small out-of-round places on the outside diameter, in the vicinity where the bearings rest on a Neufinder (or other bearing-based spine finder). That will affect the position at which the shaft "wants" to rest, but will have no effect on the performance of the shaft during a swing.
You have this interesting belief that flex asymmetry and shaft bend have the same effect on performance. I'm not sure where the belief comes from, but I know of no organized evidence to support it. The few tests I've seen to determine the effect of small bend on an otherwise symmetric shaft have not given the performance differences that folks have observed from spines.
Hope this clarifies things, DaveT
