[link redacted at request of site owner - Jul 25, 2015]

Bridge Crown

John Hartman [link redacted at request of site owner - Jul 25, 2015] [link redacted at request of site owner - Jul 25, 2015]
Tue, 02 Dec 2003 11:21:52 -0500


David Love wrote:
> Nice photos.  One obvious question is that even though the bridge was
> creating a portion of the crown on the detached panel, how much crown would
> it actually support under tension.  From previous posts on this topic the
> answer seems to be virtually none.  So if the crowned bridge was part of
> the design to support crown under tension, it would appear that it would
> have been for naught.  What do you think?


David,

Take a typical rib with crown and place in on a flat bench. Press on it 
and it will flatten with little effort. Does this mean that crown along 
the ribs is of little use to supporting bearing? Experience building 
soundboards shows that the crown along the ribs does influence the 
board's ability to support bearing even though each individual rib 
appears to be too weak to do this.

The bridges, panel, ribs and rim all contribute to supporting bearing. 
So improving the performance of the bridge by machining a crown to it's 
bottom should contribute to the overall performance of the board.

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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