Weekly Piano Tips
Why tune your piano 2 times a year.
The piano sound board is what makes the piano go in and out of tune. If during a very humid season (summer) the soundboard will absorb moisture and swell. This pushes added tension against the strings which causes them to go sharp. The opposite effect happens when during a dry time (winter and the heat is on) the soundboard will release moisture and take tension off the strings and the piano will be flat.
If the piano is not tuned for a few years this moving back and forth of the soundboard will make the piano go our of pitch and cannot be tuned without doing a pitch raise (to A440) first.
Other causes of going out of tune
Loose tuning pins are a major reason pianos go out of tune. The tuning pins cannot hold the tension due to a low torque value. The wood around the pin needs to be relatively tight. There is a min/max torque value. Too much and you can’t turn the pin accurately enough to tune and too loose will just not hold the pin from sliding back. This is when a rebuilding should be looked at.