Broken Piano Plate! Who is Responsible?

A plea for advice about a distressing occurrence comes from New York State:

“As a former member, retired, I am seeking some information. I pulled up an old piano 1/2 note to 440 pitch, informing the man it was risky to raise the pitch. In doing so, after the pull-up, the plate [cracked] in the treble section. What I want to know is, who is responsible? This is the first time this has happened to me in 58 years tuning.”

Some [technicians] tune pianos for a lifetime without ever experiencing a broken plate. But it does occur once in a while. It is always sudden and unpredictable, the result of some unseen internal strain in the plate. It may be the result of metal fatigue in a plate that was never quite perfectly fitted to the heavy wooden frame of the piano, but was forced to conform to it by the many bolts and screws. It may be the result of slight and gradual changes in the wooden frame itself, to which the cast-iron plate is not able to accommodate itself. It may be the result of a hidden weakness in the casting, which finally “lets go.” It is, as I say, a rare thing, but it does occur. It has been known to occur when the piano was sitting idle by itself, with no tuner within miles!

It is safe to assert that a “healthy” plate, properly designed, properly fitted and secured in the piano, will not break under the ordinary stresses of the tuning process, even when the string tension is being raised back to standard after long neglect. It is designed to stand much higher stresses than those set up by strings tuned to standard pitch.

There is even some question whether such a plate could be broken by deliberately over pulling the strings or whether the strings would not break first. But since the tuner does not do this, the question is academic.

So there is no basis for considering the tuner to be responsible for plate breakage that occurs during or after tuning. This fact is easier for customers to accept if they are forewarned that there is risk involved in raising the pitch of a piano. That this risk is extremely small is shown by the fact that our inquirer tuned for 58 years, including, I am sure, hundreds of pitch raises as drastic as this one, without ever experiencing a broken plate.

Don Galt

We have a sample issue from the Piano Technicians Journal which is about the piano plate. [Download PDF] 6.9MB