I often encounter repetition springs strong enough to hurl the hammer up out of check, but not strong enough to support the hammer assembly while winking the jack tender: Symptoms: The jack won't return under "test" conditions, even with the rep. lever set much higher than tolerance. Note: The back end of the lever "bobs" (Ed Foote started the maritime metaphor!) up/down when you wink the jack. After several discussions and experiments, I'd kind of resolved loose repetition-flange pinning was the sole culprit. However, on two recent instruments (Yamaha/Steinway) it was the hammer-flange pinning causing the problem. In each case, both the hamnmer and rep-lever flanges were in the 1g friction range, or less. Repinning the rep- levers even to 7 or 8g slowed hammer-rise very little, meaning the springs couldn't be strengthened much, and didn't solve the support problem. However, repinning the hammer flanges to 3-4grams, did. Regarding Steinway, the loose pinning (currently 20% RH at this particular venue), coupled with raising the hammer line several mm (key-dip; a very skinny .400") brought about the dread CAF on several notes. (see Eric's test) I called David Kirkland at Steinway for help, and he had a set of rest cushions on their way before I could spit out the last digit of the instrument's serial number. Thanks David! Mark Cramer, Brandon University PS Sometimes the traditional rep-spring strength-test is indicating a loose center, not sufficient spring strength. Try the hammer center first. > >> > >>"catastrophic action failure". > >> > >>I have a test for this that I call the "absolute test for minimum action > >>function" i.e. - will the note work? > >> > >>Play a note at a normal blow and after it checks, lower it to rest > >>position very slowly. Then give the note a sharp blow. This will uncover > >>a myriad of little problems which can result in non- functionality. > >> > >>Eric Wolfley, RPT > >>Head Piano Technician > >>Cincinnati College-Conservatory of Music > >>University of Cincinnati > >> >> >>Yea, I learned that knots will capsize if tied incorrectly or used > >>incorrectly, just seemed to fit the action condiition formerly referred > >>to as > >>"catastropic action failure". > >>Regards, > >> > >> > >> > >>Ed Foote RPT > >>http://www.uk-piano.org/edfoote/index.html >
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