>>> Since you mention the vacuum press for making laminated >>>soundboards can I assume you've decided that laminated soundboards >>>are superior to solid boards for giving the results that you want? >>>Phil Ford >> >>Yes, I now believe the laminated panel is vastly superior in >>performance to the solid panel.... After applying glue to the ribs >>and quickly removing the panel from the conditioning box, it is >>placed onto the telescopic guide pins, then the weight of the panel >>compresses the guide pins down until it rests on the rib set. >>That's it, just placing the diaphragm over the whole 'shabang' and >>turning the pump on is all that's left to do. > >This sounds like an efficient way to make up a soundboard. > >>After much consideration, I am now of the view that I probably >>won't ever use a solid sound board panel.... I am referring to >>carefully built laminated panels, where each laminate is >>constructed as if it were to be a first quality solid sound board >>panel, but 1/3 the nominal thickness, ie. properly quartered boards >>shot and joined properly with no air gaps. Three of these 2.5 mm >>thick panels make up one laminated panel (we sand the middle >>laminate to 2.5 and the outers to 2.8 - this allows for some final >>sanding after they are glued together). > >How did you decide on 3 laminations, rather than, say, 5? > >>There are several compelling reasons why I believe the laminated >>panel is superior to the solid version.....cracks in a laminated >>panel are almost unheard of. >> >>So the laminated panel, with cross grain which is much less prone >>to change dimension with hygroscopic variations, will result in a >>panel which is more stable regarding tuning stability. After having >>some experience with laminated panels, and after finding that there >>is almost no shrinkage of the panel when dried down to 6% moisture >>content, I would doubt if CC boards could be made using laminated >>panels, since to achieve any noticeable crown, one would almost >>certainly have to crown the ribs. > >I think you're right that CC methods wouldn't work with a laminated >panel. I also agree that a laminated panel seems superior to a >solid panel for a host of reasons. From a performance standpoint, >the only reason that I can think of to use a solid panel is that it >might be better sonically. I can imagine that this might be true, >but I can't imagine what the reasons would be. I suppose the only >practical way to establish this is pianists ears. If they say that >there's no discernible difference, or that the laminated panel >sounds better, I see no reason to use a solid panel. Some low end >manufacturers might prefer solid panels, since I imagine they might >be easier and cheaper to make. I wouldn't think the difference in >price would be a consideration for a high end maker. > >>We are running the top and bottom laminates in the same direction >>as for a traditional solid panel, ie. along the line of the long >>bridge, with the middle laminate at 90 degrees and parallel to the >>sound board ribs. While some might see this as a disadvantage, >>since 1/3 of the panel thickness is oriented with the ribs, I don't >>see any problems associated with it. Certainly the laminated panel >>is somewhat more flexible along the line of the long bridge, and >>stiffer parallel to the ribs, but the long bridge if adequately >>dimensioned will be more than capable of ensuring the whole >>assembly maintains its togetherness. With a rib crowned board, the >>most important job the panel has do is to ensure that air doesn't >>leak past the ribs when they go up and down. The laminated panel >>will do this without encouraging variations in crown as moisture >>levels change. >> >>Ron O. > >This topic of grain orientation has been discussed before. It's not >clear to me that there is any inherent advantage in orienting the >grain along the bridge. I can't think of a structural reason. Once >again, the only reason that I can imagine is a sonic one. Perhaps >the board behavior is influenced in some significant way by the >panel grain direction. Or perhaps it's not so much the absolute >grain direction, but the grain direction relative to the orientation >of the ribs. I've certainly seen many older pianos with various >grain orientations. But they generally seem to have the panel grain >nominally perpendicular (more or less) to the ribs. Perhaps things >were set up in this way because they were using the ribs to help >crown the board. Perhaps this layout is important for the >vibrational characteristics of the soundboard. I don't know. Here >also, I suppose the practical way to establish this would be >listening tests. If there was no discernible difference then it >seems to me that from a structural standpoint the most advantageous >grain orientation would be perpendicular to the bridge (parallel to >the ribs, assuming that the ribs are not oriented in a fan pattern). > >Thanks for the detailed response. I look forward to playing one of >your pianos with a soundboard of your own construction. > >Phil Ford
This PTG archive page provided courtesy of Moy Piano Service, LLC