David Love wrote: > A point made earlier in this discussion about the tightness of fit around > the perimeter brings up a question. I know that some soundboard installers > prefer to do the bridgework with the board out of the piano, i.e. notching > and pinning. So, they lay in the board, and put the plate in on top, clamp > in a few key places, wedge the board down under the struts and set the > bearing, take everything out and notch and pin the bridge. With a certain > amount of gap around the perimeter of the board, you would think that the > board would move outward slightly in the wedging process such that setting > the bearing would give a different result than when the board was actually > glued in. Any comments on this method and whether it presents a problem? David, I set DB with the bridge glued on and the SB dry fit in the case. The plate is clamped in with wood spacers between the plate bosses and the SB. Wedges are used to pre stress the board so that DB can be set with the SB at its point of equilibrium. Later after all the bridge work is done and the SB is glued in DB is checked before the bolts and screws are installed. I am not sure about the sliding problem you mentioned (I can't see this happening) but I always find that the plate needs to be a little higher. It seems that the SB is a little stiffer (about 20% ?) when it is glued in. I can tell this when I install the wedges. This would indicate that the rim does contribute in some way to the stiffness of the SB. Weather it does this by preventing the ribs from sliding or by preventing them from rotating I am not sure. I do not have the information in front of me but as I recall that a beam that is clamped at its ends is stiffer than one that is not. I am now building and installing my 200th Soundboard (A guess based on dwindling shop supplies and fatigue) and have found this increase in stiffness to be predictable. 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 [link redacted at request of site owner - Jul 25, 2015]
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