Cylindrical Crown, Was: Killer Octave Question

[Ron Nossaman]

>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>.

Nothing tired about that old Knabe bridge. It's still stiff as a piece of 
maple, and gravity works on it quite well. Does that vertically laminated 
long bridge you made happen to be straight?

>>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.
>
>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).

This is the case until the board is glued into the piano, at which time 
crown along the grain appears. It's unavoidable unless you have no crown 
along the ribs. I thought I'd mentioned that pretty thoroughly. It's not 
something you design or build in. It's something that happens as a 
consequence of rib crown and a relatively plane rasten.


>So much for spherical crown, right?

Soundboard crown never has been spherical in the piano.

Ron N