Cylindrical Crown, Was: Killer Octave Question

[Bill Ballard]

At 11:08 PM -0400 4/14/03, Farrell wrote:
>I did the same thing to my flat Mason & Hamlin long bridge as Ron 
>suggested. I put a small dowel under somewhere near the middle of 
>the bridge. I can't balance it though, the midsection of it simply 
>rotates up and the two ends remain in contact with the table. How is 
>it yours balances when oriented bottom down and a pencil under the 
>middle?

Hexagonal core of the standard #2 pencil. I was simply trying to 
repeat Ron's demonstration, although that paragraph in my post may 
have missed a sentence or two to make that clear. My bridge remained 
flat whether sitting on the granite bench top, or balanced at the 
middle, ends in the air. I'd like to suggest to Ron those little blue 
pills for the difficulty which his tired old Knabe long bridge has 
with gravity <g>.

At 11:02 PM -0500 4/12/03, Ron Nossaman wrote:
>An old Knabe bridge, lying on a table and propped up in the middle 
>with a pencil, shows a lovely crown from end to end. Pull the pencil 
>out, and it's dead flat. That bridge will lay on a crowned 
>soundboard and very nicely conform to the crown of the board.

At 11:08 PM -0400 4/14/03, Farrell wrote:
>"Regardless of Terry's bald dome sticking through his topless hat..."
>
>I don't even remotely resemble that!

Cool your jets, Home. I was talking about the basketball. (Jeezum. 
touchy, touchy....)

At 8:20 PM -0500 4/14/03, Ron Nossaman wrote:
>I almost asked how many times it had happened to you, and were you 
>able to fix it, but I stopped just in time.

Usually I can take care of that kind of situation with a simple 
tuning. I'm doing a Well Composted Temperament.

At 8:20 PM -0500 4/14/03, Ron Nossaman wrote:
>Nope, it's simply the shape of crown formed by the ribs. It's a 
>consequence, not a design feature. And you're right, it's the ribs, 
>or panel compression cross grain in compression crowned boards, that 
>support bearing. That is, if anything does. And as long as there's 
>positive crown along the ribs, there will be crown along the panel 
>grain.

One remaining piece which didn't make it through the grinder last 
night, the tail (I'm thinking of taking it to a taxidermist for 
stuffing and mounting). Nowhere in any of this is mention of crown 
along the grain. It will be there temporarily while the board is in 
the belly press, but once out of the press there's no reason for it 
to be there (nor is there any need for it). So the crown is not 3D 
but 2D. I'd use the terms spherical and cylindrical, except the shape 
of the cylinder (the placement of the crown) isn't straight but 
follows the bridge (so as to best support the string load).

So much for spherical crown, right?

Bill Ballard RPT
NH Chapter, P.T.G.

"Did you find that listening to your father's records gave you a clue 
to who he was as a musician?"
     ...........NPR "Fresh Air" host Terry Gross to Ravi Coltrane son 
of John. As always, asking the tough questions.
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