Hairline cracks in Treble Bridge

[BobDavis88@aol.com]

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In a message dated 11/17/2005 5:26:52 AM Pacific Standard Time, 
anrebe@sbcglobal.net writes:
It is possible that there is a beating in single strings caused by 
loose bridge pins due to cracking in the bridge.  Put a solid piece 
of metal up against that pin and if it quits, you've found it.  If it 
only loses volume, you're just damping it.  
I agree with this and your other suggestions to diagnose the problem before 
deciding on which avenue to pursue. It would also be a good idea to check 
soundboard crown and downbearing, as negative bearing can cause false beating even 
on tight bridge pins. But...
Re-seating the bridge pin 
in epoxy is a good solution for loose bridge pins where there is 
cracking (otherwise going up a size is good too and somewhat less 
permanent).  
I don't think going up a size is such a good idea. Filling the crack with 
epoxy or CA to stop the movement of the top of the pin is better than driving a 
larger wedge in. Also, a larger pin will increase the side bearing, and 
therefore the forces acting to separate the crack. 

Recapping would depend upon a more thorough assessment of the condition and 
value (including sentimental value) of the piano, and its owner's long-term 
plans for it. It's usually more appropriate during a major rebuild, when the 
strings and plate are out of the way. The cap is usually less than a quarter of an 
inch thick. If only the cap is replaced, the holes in the bridge root need to 
be plugged, and the cap material glued on, drilled in place, then notched; 
or, the root needs to be cut down and leveled, and a thicker cap installed. 
Either method is hard to do with the plate in the way. 

Bob Davis

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