On 1/31/2013 7:55 AM, Jim Ialeggio wrote: > From a straight mechanical connection perspective: > > In this case, where there is a cantilevered bridge, creating a torsion > stress on the foot to begin with. Glued or not, the curved shape of the > foot would result in reducing the available connection to the soundboard > panel at least in half. Curved shape? The foot should be flat. Why would it be curved? > This bridge will want to rotate under load. The > load will be pulling up at only the screw locations, pivoting at the > back edge of the foot. If the foot is screwed down, the action will be just as if it were glued because the mating surfaces would be in full contact. The stress will be greater on the screw and the wood, but the function will be similar. If there were a gap between the mating surfaces, yes, you would lose much of the input there as the bridge moved without moving the board much. > If glued, the upward restraint is spread evenly > across the entire span of the front of the foot. In order to pivot, the > glued foot needs to bring the soundboard panel with it (which under > serious load it probably will). From a mechanical standpoint the screw > only connection seems a bit optimistic, unless downbearing is kept near > zero. People have for years been trying to tell me that tuning pins move back against the plate holes because the block rotates, ignoring the wide contact surface between block and plate that would prevent that. Same here. If the screws are still tight enough to hold the mating surfaces in contact, the connection will be solid enough to work. No, it's not anywhere near ideal, but it's also not obvious from the sound produced. Ron N
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