Susan re. "Shear"

[Ron Nossaman]

>You're right. I should have said 'and still be called a shear force as long
>as they are parallel and opposing directions. For our reference the bridge
>top is one plane and the string trying to slide across it is in another. I
>apologize if I confused the issue. Scissors shear what it is cutting as the
>forces are not in the same plane vs wire cutters in which the forces are in
>the same plane. Clear as mud?
>Keith R

The bridge top and any sliding direction the string may indulge itself in 
thereon are indeed parallel, unless the string is going to slide on the 
bridge top in a perpendicular direction, cheese cutter fashion. But the 
string sliding on the bridge top is just that, and hasn't much to do with 
shear stress on any glue joint that I can see except maybe that between the 
cap and root, and the root and apron or soundboard. These are the joints 
that are parallel to the forces applied. The stress on the bridge pin, and 
glue joint (though it's not a joint) between the bridge and the bridge pin, 
is perpendicular to the force vector, and subsequently isn't shear. It's 
stress, compression or tension, for the short time that the CA actually 
adheres to the pin. The scissor/wire cutter example is something so 
altogether different than what the bridge/pin interface is subject to, that 
it only applies in an oblique sort of way. I understand your intent, but 
it's an off track diversion.

Ron N