Farrell wrote: > Can anyone quantify the potential problems? I can see that regarding > the belly, it will lessen downbearing, and regarding the action, it > will cause the action frame to not sit flat on keybed, or if it does > curve with the keybed, the hammer height will get affected, etc. The construction of squares is that the action sits where effective framing might be. This is counteracted a little for late squares which have substantial wooden nameboard stretchers and nearby bass struts, but their effect is lessened by over stringing and relatively high tension. Bottom boards often are oriented to the main direction of the strain but which are coupled mostly through the case sides, with grain oriented parallel to the bottom which can distort some even before transmitting some of the burden to it; further, if a bottom is solid, it cannot resist any non-longitudinal, twisting strains so well. Another weak point in old squares is at the intersection of the spine and treble end of the wrest plank, a sort of sinusoidal distortion can be observed by sighting along the spine. Even while there may be no such evidence, you may see a flange or thicker section of plates in late squares around this same area. > The question being, does the amount of cheek lift in an old square > grand change much with strings in or out? Yes, but probably you're familiar with compression set through Del Fandrich's posts regarding soundboards. This is another sort of creep, like to old shelves and beams sagging under continuous load which will spring back when the load is removed but not fully. > Do we ever see piano case bending (front to back) in a > modern/traditionally designed grand ... ever bend up (front to back) > under string pressure? It is very common in old wooden framed grands. I just checked my oldest grand, ca. 1860 which doesn't exhibit this - however, its top strut is 70mm high and which is mortised into the cheek. Clark __________________________________________________ Do You Yahoo!? Get email alerts & NEW webcam video instant messaging with Yahoo! Messenger. http://im.yahoo.com
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