Owen wrote: Ron, Would gluing on an uncrowned long bridge not force some of the valuable and available crown out of the rib/board assembly? Owen Greyling, RPT Ontario, Canada Owen, Your right, it would. I have noticed this while building soundboards. If the bridge is flat it fights the crown of the ribs as it is clamped into the case. I am no scientist and I don't have a degree in engineering but it seems perfectly logical and consistent to machine the bottom of the bridge to more or less follow the crown created by the ribs. I would think this would add to the overall strength and durability of the whole soundboard. I don't know what it does to the tone but a soundboard that lasts longer will sound better longer. I have worked on many brands of grand pianos and have observed that some pianos seem not to have this feature but the two brands that consistently show evidence of bridge crowning are Steinway and Mason and Hamlin. Newer ones will have more crown than old ones indicating that the crown does dissipate over time but not as fast as the ribs. Large pianos have a much more noticeable amount of crown than the little pianos. As some have suggested tilting the bridge back would accomplish the same thing. I don't think so. Most bridges I see are curved in both directions as seen from the top. Besides it would be more difficult to plane a slight bevel to the bottom of the bridge rather that cutting a crown into the bottom. Tilting the bridge in this way would also screw up the position of the unisons moving them back. It is fairly simple woodworking to re-machine the crown into the bridge root or to machine it into a new bridge. So I say let's retain this feature. Who knows, maybe our predecessors in this business knew what they were doing. After all they made a lot more pianos than we ever will. John Hartman RPT John Hartman Pianos [link redacted at request of site owner - Jul 25, 2015] Rebuilding Steinway and Mason & Hamlin Grand Pianos Since 1979 Piano Technicians Journal Journal Illustrator/Contributing Editor
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