>After raising pitch 50-100 cents,and leaving the piano at 440 I usually >expect the piano to drop and need another tuning within a few weeks. Does >this suggest that I am missing something? > >Sid Blum Hi Sid, Obviously, something is moving, but why does it have to be the plate flexing? When you raise pitch 100 cents, you most likely aren't going to get tensions in the string segments fore and aft of the bridge equal. Over time, temperature, and humidity changes, the string will tend to render through the bridge gradually until those fore and aft tensions are pretty close. Since you pulled the segments between the bridge and pins higher than they were, the segments between the bridge and hitch will probably be of lower tension that what you just tuned, so the pitch drops at the back scale steals tension from the speaking length (etc). If you leave more tension between the agraffe and pin than there is in the speaking length, the pitch may go high first (since there is less friction at the agraffe than at the bridge pins), then low later as the string slowly renders through the bridge. Anyway, that's my take. Ron N
This PTG archive page provided courtesy of Moy Piano Service, LLC