Grand Regulation – part XXIII

Step 37 – The Repetition String Strength 
Next step on the 50-point checklist is number 37, adjusting the repetition spring strength. What we want is to have the springs adjusted as strong as possible, without the pianist feeling it work at the key. This allows the repetition lever to support the knuckle after the hammer is released from the backcheck,.and enables the jack to return to its rest position as fast as possible. Note that during the actual playing of the piano action, the hammer does not rise in order to let the jack get back to its position.
This is just the way that we think it happens, since that is the way we see it while regulating the repetition spring strength. What really happens is that the whippen drops, while the balancier supports the knuckle, leaving room for the jack to get back to its rest position. Step 36 just previously performed was regulating the backcheck distance. Other than a very minor effect that the jack height has on the repetition spring, the backcheck distance is the only thing which affects the regulation of the repetition springs. This is why the backchecks and the repetition springs are always regulated as a pair, and in that order. A special note should be made, however, concerning the drop screw. If for some reason the drop screw is adjusted too far down, there will appear to be no rise in the hammer while checking for the correct repetition spring tension. The repetition spring will still do its job, but no rise will be seen. The balancier can not raise since the drop screw inhibits that rise. If this phenomenon occurs while regulating, simply raise the drop screw a little.

It is interesting that the repetition spring affects the drop as well as the drop affecting the repetition springs. If the strength of the springs is too weak …

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