On Sun, Oct 24, 2010 at 3:02 AM, David Lawson < dlawson at davidlawsonspianos.com.au> 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 > As others have said, it happens. In my locale, RH varies from 15-70%, and changes in lost motion are particularly obvious with pianos that get service every six months. There is not as much change as you mentioned, but there is change. Rather than adjusting the capstans each time, I insert small pieces of bushing felt (or some other shim) under the hammer rest rail. These can be removed after the next humidity change. -- JF -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/pianotech.php/attachments/20101024/2f03c8a4/attachment.htm>
This PTG archive page provided courtesy of Moy Piano Service, LLC