anyone ever dry install the head on a shaft , clamp it in a freq. meter with the toe up ,face pointing to an imaginary target [right handed club] and twang it to see if you could the head to "run flat" or flat line ? if you rotate the head on the shaft , then reset it toe up until you you can get a flat line run , what does that tell you about a shaft/clubhead assembly? Ray ----- Original Message ----- From: "Bernie Baymiller" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Wednesday, October 08, 2003 5:36 PM Subject: Re: ShopTalk: NBP-COG
> Tom, > > You need to build yourself an NF2. If I rotate to the spine on my NF2 with a > dial indicator and can read the deflection in thousandths, as well as see > the deflection go up as I go toward the spine, and see the resistance > direction of the shaft and its affect on the dial indicator's probe, then it > is obvious to me that the point of least stability is a spine, or stiffer > point on the circumference of the shaft. If there are two, I can measure > them both in thousandths and know which is the S1 and which is the S2, as > well as their magnitude from the NBP deflections. > > I think that if I mark the location of the NBP, a dead stable point, with > the accurate marking guide (dead center over the shaft on an NF2) on the > wider section of the shaft just below the grip, that I can get closer than > 4° in an NBP-COG alignment. In fact, since gravity pulls the head to the COG > (I hope), my only alignment variables are my NBP marking accuracy and my > ability to put the NBP exactly at 6 o'clock. Since the marking guide is very > close to the flexed shaft, I think that I can mark it within 2°...but > whether I can get the NBP exactly at 6 repeatably, I'm not sure yet. I made > a small jig from a section of graphite shaft that is exactly 1/2 the > circumference of the shaft at the point I mark the NBP. This allows me to > put a mark 180° from the NBP, which I will be able to orient at 12 on a > table top. Of course, this assumes I'm using a similar-diameter shaft at the > marking point. > > Another way that I've tried marking the 12 o'clock point is to put the > NBP-marked shaft in my Workmate slot and close it up to the point that I can > just rotate the shaft. Looking up from underneath, I can center the NBP mark > in the small slot, then mark the top dead center. There are probably some > other ways that might work better. > > How've you been playing lately? Is your lurch still lurching down the > fairway? I was just getting consistently back into the mid-high 70s when I > tore up my left shoulder (probably rolled over in bed the wrong way) about a > week ago and might not be able to play for at least a couple of weeks. Then, > it'll be back to trying to break 80 again. There is always another challenge > for us senior players. :-) > > Bernie > Writeto: [EMAIL PROTECTED] > > > ----- Original Message ----- > From: "tflan" <[EMAIL PROTECTED]> > To: <[EMAIL PROTECTED]> > Sent: Wednesday, October 08, 2003 1:03 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 > > > > > > > > >
