Ron and list, Thanks for the reply. I'm glad you had a close look at some pins. This is the type of applied theory I like to see. I've often said that a good thinker is one who can figure out why nine out of ten of his bright ideas won't work before he even tries them. In my first post I stated that the strings don't move on the pin. Let me clarify. Certainly they move, after all there's a whole lota' shaking goin' on when the piano is played, but I don't believe there is enough friction between the string and pin for the string to hang up on the pin, hence my original statement. The string will always return to its point of least deflection quickly. The marks on the pin do indeed tell us that the string is moving on the pin somehow. I think these marks are an indication of the changing of the string's point of least deflection as the bridge becomes grooved. The string starts at the high end of the mark when the bridge is fresh/ungrooved. It won't stay there long though because this is maximum deflection where the most/quickest grooving happens. As the grooving progresses over time the string will find its point of least deflection lower and lower on the pin. The string then moves down the pin forming the mark. The travel of the string and formation of the mark on the string happens more quickly at first, then more slowly as the the deflection becomes less and less. This is why the mark is wider at the bottom. The string has spent more time at the bottom as it nears zero deflection. Would you agree that the mark appears to be a swipe mark and not multiple individual indentations? If so, that would confirm both the lack of friction to hold the string up and the non-linear decent of the string over time. Gotta' go, I'm off to Wisconsin Days! Richard Anderson
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