Wiser heads will probably have better ideas, but is it possible that the keybed itself tried to expand lengthwise from humidity, was constrained by the case, and bowed upward instead? Is the problem uniform across all registers, or is it worst in the middle? Susan Kline, Oregon, it's raining and windy and warm: "Hawaiian Wet Front" slamming through. On 10/24/2010 1:02 AM, David Lawson wrote: > I regularly service about twenty pianos at a Conservatorium, both > uprights and grands. The uprights are mostly Yamaha U1 models about 15 > to twenty years old, with a couple of Kawai KS models also. I regulate > the lost motion on these instruments so that the capstan holds the > wippen so there is no lost motion, however, it is not holding the > hammer off the rest. I have just finished the regular maintenance of > these this week, and discovered that all but one had increased the > height of the capstans to hold the hammers off the hammerest by about > 1/4 inch or 6cm. My first reaction was that someone had been at them, > turning up the capstan. However, this is not possible as I am the only > tech. who attends to these pianos. > So, my question is this: Would the sudden change from drought,(about > ten years) to very wet conditions, have brought on this amazing > change? I find it difficult to believe that this much change could be > brought about by humidity. Let's face it, the metal pin holding the > capstan is tight into the rear of the key, which would surely not > increase the height by this much with humidity! I checked the back > touch on the key-frame, and it seems quite normal.The only piano that > did not have this happen to it, had an additional heater in that room, > which may give us a clue. > Your thoughts please. > David Lawson Wangaratta Australia -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/pianotech.php/attachments/20101024/c7717af6/attachment.htm>
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