Terry, and others following along. After reading back and forth a few times I find myself in agreement with you on everthing except this one point about what happens when glue comes into the picture. You seem to be saying that when there is glue present between the bridge pin and hole then some shear stress is present that isnt there without the glue present. A couple posts back you said : "..., if the pin were also glued to the wood in its hole, until the glue completely fails, there would be a shear stress between the pin and the glue and the wood on the forward and rear side of the pin (where the pin would be sliding past the stationary wooden bridge during its migration)." Thats where I get confused. The direction of the force from the string is the same, as is the resistance from the bridge. The pin still stands more or less perpendicular to these. The only thing that has changed is a thin layer of glue between the lengthwise surface of the pin and the inside of the bridge pin hole. I think you are saying that at the very top of the hole, half the pin/glue/wood surface is under shear stress, and the other half is under tension/compression,,,. But if this is so, how significantly does this change the total picture, and how does any of this figure into bridge cracking ? Just about there methinks :) I think I read you clear now on the rest of it. Thanks for your patience Terry. :) RicB
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