String Spacing on Bridge

Michael Spalding spalding48@earthlink.net
Tue, 25 Jan 2005 09:41:28 -0600


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Terry,

For a given piano length, lessening the string spacing would shorten the low tenor strings.  Not a positive change in most piano scales.  Also, the heavier low tenor wires put a higher side force on the bridge pins due to their stiffness, so larger pins and wider spacing would reduce the bridge's tendency to crack.  Bad grain orientation aside (Knabe) most bridge cracking occurs around the closely spaced small pins in the high treble, or on the bass bridge where string tensions are greatest.  I could imagine that these factors were discovered during the transition from parallel-strung to overstrung designs, and also as string tension increased as cast iron plates were incorporated.

Mike


----- Original Message ----- 
From: Terry 
To: pianotech@ptg.org
Sent: 1/25/2005 5:55:38 AM 
Subject: String Spacing on Bridge


On most (all?) modern pianos, the mid and upper treble strings are roughly parallel to one another. However, in the tenor, and more-so in the lower tenor, the strings are spaced much further apart over the bridge than they are up near the forward speaking length termination.

Why? I ask that especially because I have heard much talk of design/performance concerns about the low end of the long bridge being too close to the rim - why not just lessen the string spacing and have the long bridge end further from the rim?

Terry Farrell
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