Overs laminated soundboard

[Phillip Ford]

>>>   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