> Farrell wrote: > > > > > I guess this is where I am getting hung up here... I can > > easily accept that there is a shear force exerted on the > > bridge pin getting "pinched" as it were between the > > string > > pushing at it from the one side, and the bridge from the > > otherside. > > I believe the above described a compression force of the > string toward the pin, and a second compression force > between the pin and the wood on the other side of the pin. > If the pin had been glued in, then there would also be a > tension force between the pin and the bridge wood directly > under the string. > Yes... or said another way... The bridge and string together exert a shearing force on the pin (ie the pin is under some degree of shear stress). Yet the string and pin share a mutual compressive stress as do the pin and bridge hole. And tho the relationship between the bridge and pin is much like the nailed plate example above... the relationship between the string and pin is really just plain compressive force me thinks. All in all,,, this adds up to the only real shear stress involved being exerted on the cross section of the bridge pin exactly on the plane of the opposite forces created by the string pushing the pin against the bridge holding the pin. >If the pin had been glued in, then there would also be a tension force between the pin and >the bridge wood directly under the string. There would be anyways.. just not exerted on the glue but on the two (parallel, lengthwise) surfaces of the pin and bridge pin hole. Agreed ? Grin.... I still am not sure whether or not we are on track with each other here or all mucked up by word usage. Great fun eh ? RicB
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