Don, Yes this will do the job as accurately as any method I'm aware of.
BTW, some of us do believe that a spine finder does find the correct NBP, that it should be a combination of flex differential and shaft geometric anomalies that determines this location. Dan Neubecker [EMAIL PROTECTED] >-----Original Message----- >From: Don Flatgard [mailto:[EMAIL PROTECTED] >Sent: Wednesday, October 08, 2003 4:49 PM >To: [EMAIL PROTECTED] >Subject: Re: ShopTalk: NBP-COG > > >NBP-COG alignment..... >I posted this the other day and received no response so I'll >do it again. >I agree with you on the difficulty of aligning the NBP and COG to the >degree. >My method is to prepare the shaft, install the ferrule, find >the NBP with >the NF. Take the DI off, turn the NF up-side down on the bench >and install >the head and let it seek it own COG, let the epoxy set up with >the club in >the NF. >In my small mind I don't see how you could get any closer....df > > > >----- Original Message ----- >From: "tflan" <[EMAIL PROTECTED]> >To: <[EMAIL PROTECTED]> >Sent: Wednesday, October 08, 2003 12:03 PM >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 >
