Abstract: A balance pin assembly for mounting a piano key includes a balance pin, a mounting insert, and a self-locking pin. The balance pin has a lower externally threaded base, an intermediate annular shoulder, and an upper elongated stem with a top torque regulating head. The mounting insert has a central bore and is both externally and internally threaded for threading into a hole in a piano keybed rail member and for threadably receiving the base of the balance pin to establish the desired height of the piano key above the rail member. The torque regulating head is used to turn the pin and will shear off if the pin is overtightened in the insert thereby preventing stripping of the internal threads of the insert.