Hi there Stéphane The degree of compression on the underside and top side of the board is determined by some combination of two basic conditions yes ??.. If you first take the degree of curvature of the panel and figure how much compression there is on the underside and how much tension there is top side, and then figure in the amount of compression imposed on this situation by the fact that the ribs are constraining the thing soundboard from expanding when it takes on moisture.. then you can figure the absolute degrees of compression / tension in the panel itself. Remember that the amount of compression imposed on the panel is by the ribs is not constant through the entire thickness of the panel, rather decreasing as one gets farther away from the constraining force (ribs). I have yet to hear a conclusive description of what the end condition is for a given assembly with x amount of curvature and so and so amount of compression due to the ribs. Whether or not the top of any given soundboard ends up in tension or in compression... or at about equilibrium... I'm not sure. Cheers RicB /Hi David. I thought in a CC board, the under side (the one where the ribs are glued on) is compressed due to the opposite changes in dimension of the ribs and the pannel when stabilizing the moisture, while logically, the upper side is tensionned, for the very same reason. Is this correct ? Does that come into play ? (Or did I miss something ?) I would believe, for a RC board with same curvature, the underside of the board is less compressed, as the ribs dont tear on the pannel. Best regards, Stéphane Collin./
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