Tom, Ok, I see that you did ask about the hard spot. I was thinking NBP-COG wince that is the subject line :-) In that case I agree with you. The hard spot, being the most unstable spot on the shaft, can't be precisely oriented and many of us don't care where the hard spot is, since it is not the plane that the shaft most wants to naturally bend in.
Many of us are orienting shafts based on NBP for that reason. The NBP can often be precisely found and oriented, if you believe in what a spine finder tells you. In the case of NBP to any related clubface alignment, it can be done quite precisely. Dan [EMAIL PROTECTED] >-----Original Message----- >From: tflan [mailto:[EMAIL PROTECTED] >Sent: Thursday, October 09, 2003 4:13 PM >To: [EMAIL PROTECTED] >Subject: Re: ShopTalk: NBP-COG > > >Uh; > >I didn't mention anything about NBP-GOG. What I said was its virtually >impossible to assemble a club with the "hard spot" in a >precise position. I >have a spinefinder and a freq machine. I find hard spots - >spines, and soft >spots - NBP's easily. No problema. I don't deny the existence >of spines, >NBP's, or COG's. My argument is about marking and assembling. > >TFlan > >----- Original Message ----- >From: "Dan Neubecker" <[EMAIL PROTECTED]> >To: <[EMAIL PROTECTED]> >Sent: Thursday, October 09, 2003 6:44 AM >Subject: RE: ShopTalk: NBP-COG > > >> Hi Tom, >> >> It depends on what theory you believe in. If you believe >that a spine >> finder can find the correct NBP location as I do, then you >absolutely can >> get the NBP exactly at the COG. >> >> Bernie's post on NBP to COG alignment contained a quote from an >experimental >> set I made up. I did not have any high expectations for >that set when I >> made it up. Let me tell you that I was shocked by the >difference in the >> results. The results continue today after months with this set. I >continue >> to hit the best irons of my life. Now this set was a >combination of new >> things for me. First, I used a new shaft, PC Mach 22's, >with R+, S- and S >> shafts in the set. I used my NF2 to tip trim them to a >matching profile >of >> .010" deflection between clubs, never having to trim more >than 1/2" tip to >> do so, and the find the NBP locations. Then I made up the >clubs with a >3/8" >> change between lengths, for a poor man's MOI match. Finally >I assembled >> them using the NBP (N1) to COG alignment. >> >> It could have any of those factors, or all of them that led to these >> results, but I was literally shocked by how much better they >played than >any >> set I've used. It was the most difference I have seen in at least 10 >years >> of experimenting with clubs, different lengths, different >shafts, flexes, >> torques, components, you name it, I've tried it. >> >> I can't ignore results like that, regardless of how tenuous >the theory. >> >> Dan Neubecker >> [EMAIL PROTECTED] >> >> >> >-----Original Message----- >> >From: tflan [mailto:[EMAIL PROTECTED] >> >Sent: Wednesday, October 08, 2003 12:04 PM >> >To: [EMAIL PROTECTED] >> >Subject: Re: ShopTalk: NBP-COG >> > >> > >> >Dr Tutelman: >> > >> >A question, por favor. When this subject was broached several >> >months ago, >> >and the thread unwound for about 3 weeks, I asked a question >> >that got no >> >universally agreed upon answer. The question was; is the spine >> >found at the >> >top of the shaft or at the bottom of the shaft when testing in >> >Dick's spine >> >finder? Responses were equally, and passionately, divided. >> > >> >I then asked another question; if when one finds the spine, >> >the "hard spot" >> >via the use of our arguably primitive methods, how can one >> >accurately mark >> >and then place the hard spot in a specific position? As I >recall, you >> >responded, correctly, that we'd be lucky to get the spine >> >situated to within >> >3 to 4 degrees. You mentioned the circumference of the >.335" tip, when >> >reduced to 360 degrees, would be virtually impossible to set >> >accurately. I >> >agree. An assembler would need to identify the spine at the >> >shaft tip by >> >marking it with a needle, then mark the hosel in the >precise finished >> >position. Then he'd need to mark the ferrule so the entire >> >assembly could be >> >stuck together in one operation. That's nearly impossible given the >> >workplaces of most assemblers. >> > >> >So, this thread re; placing cog/spine in some specific location with >> >accuracy is theoretically interesting but in practice its >pretty much >> >useless. I'm not knocking anyone, just making a point >that's been made >> >several times in the past. >> > >> >TFlan >> > >> >----- Original Message ----- >> >From: "Dave Tutelman" <[EMAIL PROTECTED]> >> >To: <[EMAIL PROTECTED]> >> >Sent: Tuesday, October 07, 2003 10:49 AM >> >Subject: Re: ShopTalk: NBP-COG >> > >> > >> >> A few points I'd like to make concerning things that were >> >brought up in >> >> this thread: >> >> >> >> (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). 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.) >> >> >> >> (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. >> >> >> >> (3) There are three theories that I have seen about why >> >spine alignment >> >> matters. NBP-COG is one of them. Here's the reasoning behind it: >> >> * At the moment of impact, the major force bending the shaft is >> >> centrifugal force. (That is probably true, but not >> >universally accepted. >> >> But let's proceed on the assumption that it is true.) >> >> * That force will bend the shaft in the plane of the CG of >> >the clubhead, >> >> because centrifugal force acts through the CG of the clubhead. (In >> >essence, >> >> it is pulling the CG of the clubhead straight away from >the hands.) >> >> * If the shaft bends in a plane where the forces due to >> >bending are not >> >> in the same plane as the bending, there will be spurious >> >torque on the >> >> clubhead; you don't want that. >> >> * But the only planes where the force and the bending are >> >aligned are >> >the >> >> NBP and the spine plane. In other planes, there will be some >> >small angle >> >> between the bending and the force in the shaft. So you need >> >to align one >> >of >> >> those planes (either the NBP or the spine) with the CG of >> >the clubhhead. >> >> >> >> (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. >> >> >> >> Hope this helps, >> >> DaveT >> > >
