Sohmer

[Robin Hufford]

Dale,
     I looked again at this piano today.  The strings cross over, of
course, the board and reach the agraffe which they pass through, THEN,
the string proceeds upward at an angle of, approximately,  about 5 - 6
degrees for about 1/4 to 3/8 inch and then turns over a round to the top
of the bridge which is about 5/8 of an inch across.  As it passes across
the top of the bridge it rises at an angle of less than 1 degree.  After
leaving the bridge the angle reverses and it inclines at about 1 degree
(I am not sure as I write this from memory some twelve hours later)
downward to the string rest and hitch pin.
      With a little trig this could be calculated but I am reasonably
sure that a force couple exists here which has the effect of rotating
the bridge backward thus the shearing stess in the board which, I think,
the crack is evidence of.  Also, in point of fact, it is about two
inches or so from the bridge.  As I repaired the crack over a year ago
and sent the piano to a refinished for some months I must rely on memory
for its characteristics but I think the side closest to the bridge was
the high side.  In fact, I feel reasonably certain this was the case
but, again, I am relying on a very unreliable item, my memory.
     Incidentally, this piano, which is from about 1930, does not have
the agraffe system in the top section or the bass.  Conventional pining
is used instead.
Regards, Robin Hufford

Erwinspiano@AOL.COM wrote:

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