Bridges: Chew on this

a440@iquest.net a440@iquest.net
Fri, 17 Nov 1995 08:56 -0500 (EST)


At 07:52 PM 11/16/95 -0700, you wrote:
>To Jim Harvey -
>
>I understand you are describing and questioning the direction the string jogs
>when crossing the bridge.  And, of course the direction of the jog must be in
>the same direction as the downward slant of the bridge pins.
>
>I think I was not clear enough in my earlier post where I recommended
>slanting the bridge pins downward toward the middle of the bridge.  Let me
>try again.
>
>Assume we're dealing with a three-string unison in the mid-range of a
>medium-sized grand, and we're inventing the bridge from scratch.  In
>conventional practice, we would drill for the front row of bridge pins by
>drilling down and to the right (leaning the top of the drill to the left); in
>this case, the strings would deflect to the right as they cross to the rear
>row of bridge pins, then turn left as they continue on to the hitch pins.
> (The rear row of bridge pins would lean in the opposite direction of the
>front row, per usual.)  In the ideal scenario, all three front bridge pins
>would be parallel and in a vertical plane; they would also be in the same
>plane as the line of the bridge notch for this note; this plane would be
>perpendicular to the speaking lengths of the strings as well.  The question
>would be, should the front row of bridge pins lean left or right, not fore
>'n' aft.  The answer is, I believe, that the front row of pins should slant
>down to the right (leaning the drill to the left); in this way, the bottoms
>of the pins will be somewhat closer to the center of the bridge's width than
>the tops of the pins are; this is a stronger construction than leaning the
>pins the other way, with the bottoms pointing somewhat outward, toward the
>edges of the bridge.  The difference would be most dramatic in the tenor
>region of a long piano, where the bridge is running more nearly fore 'n' aft.
> And the difference would be least dramatic in the high treble where the
>bridge runs more nearly left 'n' right; even here you might as well angle the
>same way, for the same reason, and for uniformity with the rest of the piano.
>
>I don't think I've ever seen a grand bridge organized otherwise, although I
>suppose it could be.  An upright, when lying on its back, will usually
>(always?) have its pins leaning in the direction opposite the grand's pins.
> The same considerations prevail, but the bridge curve is in the opposite
>direction compared to the grand.
>
>Hope I haven't confused the issue more in trying to describe this principal.
>
>- Tom McNeil -
>Vermont Piano Restorations
>
>P.S.  I agree with Don Mannino's comments, too.
>
>Tom, I am the newsletter editor for the Indianapolis chapter PTG. I found
this reply interesting. I would like permission to print it in the December
issue of the Newsletter. Please let me know as I am prepareing the
newsletter now.
Thank You.
Mike Cook
A440@Iquest.net




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