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MMD > Archives > February 1997 > 1997.02.09 > 22Prev  Next

Repetition Spring Regulation
By Jon Page

Hi John, see if this gives you a visual concept. The spring should lift at a slow and steady pace. An easy flow, as opposed to a jumping motion. (More like the rise of one's head when you comprehend something saying: "Oh, I see"; not the jerking motion as when being pushed from behind).

Depress a key and hold it down so that the hammer is caught by the backcheck ('checked-in'), ease up on your finger enough to release the hammer from the backcheck (maintaining finger on key). The hammer should rise. Adjust the spring tension to the point where you no longer feel a 'kick' or 'bump' in your finger thru the front of the key (the raise should not be of such a velocity as to bang the repetition lever into the drop screw). Treble notes (above treble staff) could stand slightly stronger tension to insure repetition on trills. I need to add: the height at which the hammers 'check-in' should to be set before the spring tension is adjusted.

This spring tension (adjusted at this minimal setting) may need to be checked seasonally as the humidity of summer may require a stronger spring tension to maintain repetition. So, repetition springs set in the summer may be too strong for the drier winter action conditions. For this reason you will generally find jumping hammers in the winter. (Too strong a tension may cause a double strike if the backcheck leather is dried out and/or not catching the hammer securely or if the action is regulated to a close let-off).

But when all is said and done, if a piano has good repetition in summer, and the hammers do not double- strike, not many people re-adjust. Only the most critical pianists can notice the difference, and as for player pianos -- the mechanism is oblivious to the finer nuances.

Jon Page
Harwich Port, Cape Cod, Mass. (

(Message sent Sun 9 Feb 1997, 16:41:50 GMT, from time zone GMT-0500.)

Key Words in Subject:  Regulation, Repetition, Spring

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