Dave, Thanks for the explanation of why NBP-COG works. Some comments below:
> (1) As Alan Brooks and John Kaufman and I have said in the past, every > shaft will have the stiffest directions (that is, spines) at 180* > intervals. Similarly with the most flexible directions (that is, NBP). That seems to be true on many graphite shafts, but when I rotate some graphite shafts and watch the dial indicator on my NF2, I can often find the NBPs and spines well off 180�. Why is that? > If you measure anything else, there is something wrong with your measuring > equipment. (Others have already noted that residual bend affects a spine > finder's reading. That is probably the most common thing that is wrong with > your measuring equipment.) I agree, and find it quite easy to spot shafts with larger bends by their deflection drop, but have seen no evidence to suggest residual bend, which can show as an NBP on a spine finder, does not affect club performance as would an NBP. > (2) FLO is important!!! It is not important because of anything the shaft > may be doing during the swing (unlike a fishing rod), but it is one of the > more reliable ways to find the REAL spine, untarnished by things like > residual bend. In other words, FLO is a more reliable spine-finder than > Colin's or Dan's. Slower perhaps, but it finds the real spine. In my limited range testing with clubs (drivers) aligned NBP to target and with FLO (near NBP) to target, as well as spine plane to target with and without FLO, I can see no difference in performance. That includes 3 or 4 of my own drivers and observing at least a dozen made for my senior friends with handicaps from 8-18 in the past two years. But, Charlie brought up an interesting question yesterday that might change my mindset, when he asked if the NBP-COG alignment was on FLO. I've checked an assembled 2W and a 3-iron, plus a 9W I made yesterday (clamped without the grip) and all three clubs were very close to, if not on, FLO. I'll have to check a few more, as well as a Spine-COG alignment and see if that is also on FLO. Maybe NBP-COG alignment could turn out to be an easier way to FLO a shaft...no clamping and fiddling around with lasers, etc.? > (4) If you build your clubs with nearly spineless shafts (like SK Fiber, or > the new Harrisons, or many filament-wound shafts), then it makes little > sense to say, "I used NBP-COG alignment [or any other alignment] and it > worked GREAT!" You were aligning an effect that probably didn't matter one > way or another. I would agree that last statement makes sense, but again, my observations and those of three other players suggest NBP-COG alignment does make a difference in iron sets, whether the shafts have an appreciable spine or not. Accuracy with my short irons is so much improved with spines measuring no more than .006" (three shafts in 9 measured .013", .015" and .016", about 3 cpm?) that I found it hard to believe. After more than 10 years cussing my mis-directed wedge shots, there was a striking difference the first round with the new set...and after 5 rounds, they continue to be straight (sometimes chunked, but straight). The heads are nothing unusual and shafts are same weight and length as my other sets...all made with a 3/8" tip trim instead of the recommended 1/2". A 90+ player, who said he generally sprays the ball all over, phoned me after his first round with an NBP-COG alignment to say he had never hit the ball straighter in his one year of playing golf...took 10 shots off his normal score. He was using Precision Superlite steel shafts. I guess time will tell. You mention "Harrisons," using the plural. To my knowledge, only the Striper J was "virtually" spineless. Are there others? Bernie Writeto: [EMAIL PROTECTED]
