Find the amount of weight that, when released on the key top, just causes the string to sound. Hold the key up with a finger on the key end (or side for black keys), position the weight on the key, then pull the finger away suddenly. Easy and repeatable. No "touch" involved. ***This is what I have been doing. Since touchweights and and friction are known to be even, everything must be uniform until the jack toe strikes the let-off button. The only things that happen after this point and before sound are 1) the jack tip escapes from under the knuckle, and 2) slight compression of the repetition spring. We know it's not the rep springs, so the only possible culprit is jack-to-knuckle friction. Since the knuckles are in uniform condition, the only adjustment that is relevant and available is jack-to-knuckle alignment. Adjust it so each key just sounds with an equal amount (or a smooth progression) of weight. If any keys cheat, increase the weight a bit and repeat. ***Sounds reasonable, however as I have repeated this static test many times, the 84 grams required (sample note #40) and 77 grams (sample note #42) to get the hammer string contact without the sustain pedal depressed does not put the action through letoff. The jack is not rotating out of the knuckle. In otherwords, it does not appear to be necessary to fully depress the key to get the softest ppp sound, only to the point where letoff begins. And, as a bonus, I have found that I can do this with my fingers. Comments? -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/pianotech.php/attachments/20100126/7a4ab1f4/attachment.htm>
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