Tuning Fork Setting

Wittner Piano Tuning Fork

To start tuning your piano by ear you need the tuning fork, It’s the most common tuning fork, it’s a standard traditional steel tuning fork, its 0.9 cents flat.
A440 is the international standard frequency.
Traditional Steel tuning forks can vary in pitch depending on temperature, you can adjust if it’s cold you can warm it up in your hand.
When setting A4 (located on the 3rd. octave) to a tuning fork you want to:

First start by striking the tuning fork on a hard surface (you don’t want to do it on the surface of the piano because you could dent the piano). Because it’s quiet you want to put the end of the tuning fork (you’ll see that there is a ball at the end) on a hard surface and with that you hear the sound vibrate and then you can tune the key or you can tap it and hold with small distance next to your ear to hear the sound.
Then once you got the tune to the tuning fork, you can check it by playing the octave below it, if it’s not completely in tune it is okay, as long as its close and you can hear an audible beat. Now strike the tuning fork on a hard surface, place the end of the tuning fork on the piano and play the note and see if the beat rate is the same.

Article courtesy Gemm Piano Supply