----- Original Message ----- From: "Farrell" <mfarrel2@tampabay.rr.com> To: <pianotech@ptg.org> Sent: April 23, 2002 4:12 AM Subject: Re: Soundboard Installation & MC > What argument would there be for drying prior to installation? With a compression-crowned board? It is easier to work with and glue into the rim if it is dry, having little crown. With a rib-crowned board there is just the matter of consistency. You don't want the board too dry or too wet--both have a negative affect on the glue bonding strength. We rib our boards at 6.5% and glue them in at 6.5% to 7.5%. > > Has this become the "standard" because the "masters" did it that way back when it was a fact that the rim supported the crown? It has never been a 'fact' that the piano rim supports the crown though many have believed this over the years. Some argument can be made that beveling the rim--as is the practice of some--does have some nominal effect on soundboard crown, but it is very short-lived. Consider that this effect is greatest in the treble region of the soundboard panel and yet this is the region that typically looses its crown--certainly the stiffness related to crown--the earliest in a compression-crowned soundboard system. Obviously, the effect is minimal. > > I suppose if you flat ribbed it and dried the bajeezers out of it, the rim just might help to hold a bit of crown - at least until it got off the showroom floor! If the rim actually did support crown you'd never see a M&H with a flat board! Wood--primarily the spruce used in the soundboard system--simply has too much compliance and is to susceptible to long-term creep for the rim to have any real function in sustaining crown. Del
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