Piano Tech Talk - Repetition Lever Spring Adjustment

April 12, 2021

Tech Talk - Repetition Lever Spring Adjustment

“Repetition lever spring adjustment” is many official words for a simple adjustment. As discussed in the two previous posts on let-off and fall, we were able to see and measure (at least with our eyes) the hammer position relative to the string. To do this, the hammer is raised very slowly and in a controlled manner.

When determining the correct spring tension in our next adjustment, the hammer must be played in a mezzo-forte manner to allow the hammer to be captured in its “checked” position. In other words, just play the note. The hammer should come to rest around 5/8” from the string. From this resting position, again in a very controlled manner, lift the key ever so slightly. You should notice the hammer make its way toward the string on its own. This movement may be terribly slow, or quick and abrupt. The speed at which it is set is determined by a variety of other adjustments and considerations. Many speeds may work, but only one will be optimal.

Having the backcheck leather in good condition as well as the hammer tail sufficiently textured will also come into the equation of what the correct tension on the spring may be. In this case, stronger is not necessarily better, and too much can be bad. In the next Tech Talk, we will be looking at the last of the primary four adjustments to the grand piano action regulation, back check.

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