Key dip is the amount of distance the key travels when it is pressed. This is adjusted by adding or removing punchings at the front rail, or by shimming the keybed. At rest the height of the key is set by adjusting the key height at the balance rail. From this the amount of dip can then be set.
Key dip is one of the most important parts of piano regulation, having a direct effect on the touch and weight of the piano key when pressed, and the effect of other regulation such as aftertouch, let-off, and hammer travel, . In brief, the greater the key dip, the lighter the touch will feel; and vice versa. Too much or too little however can significantly affect the playability of the action, and cause notes not to work.
On most keyboard instruments key dip is set to approximately 10mm or 3/8”. Some pianists prefer a shallow key dip for a heavier touch, and others a deeper key dip for a lighter touch. In larger grand pianos the dip can be greater, and Hohner Clavinets and keyboards it can be considerably less.
For Rhodes piano the key dip is not usually adjusted by inserting punchings on to the front rail, though it can be done. Key dip is usually fairly consistent in Rhodes but if needed the correct way is to shim the keybed where the dip is greater to even out the whole keyboard.
On Wurlitzer pianos the process is the same as acoustic pianos – setting key height and then adjusting key dip through paper punchings.
Clavinets are a little different. Since the hammer strikes the string directly underneath the key, the hammer tip itself is responsible for key dip, along with setting of the entire key height of the keyboard. This can be delicate process as is the dip is too shallow then the tip man not strike the string and anvil correctly.
