After finding acceptable FLO with the clubhead temporarily installed, I place 3/4" white paper tape on the shaft just above the installed ferrule and the same wrapped around the hosel below the joint. I then draw an line across the two pieces of tape with a .05mm pencil using a machinists square for a straight edge. (pencil doesn't smear when wiped with naphtha)
Assemble the club and eyeball the two lines. Sometime later, before the epoxy sets up, check and adjust the alignment by laying your eye up against the shaft looking down towards the hosel at your pencil lines. You can certainly ascertain a pencil width for alignment error and correct it if desired. FLO NEVER changes on the cured assembly.
Best,
CB
At 10:03 AM 10/8/2003 -0700, you wrote:
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
