Hi Don, A great deal of information from a lot of great minds. So thanks before I poke holes. ;-] If anything, balance holes are too tight. They don't drop freely at all, and must be "encouraged" to seat. I had actually considered that the tight balance rail holes (and possibly too thick as well) could be contributing to the crazy touchweight data I took. So I'm pretty confident dismissing that one. Most other points check out, though I would consider the back rail cloth to be firm. Not from compaction, but it just is - the piano is only 2-3 yrs. old. As to chasing a "technician's symptom," the malady was brought to my attention because it was happening during practice for the pianist. I merely duplicated the symptom (at will) after the fact. So it is, in this case, a performance issue. Thanks again for putting some thought into my puzzler. Unfortunately though, this is a piano in the pianists home and I won't be seeing it again for a bit. When I do, though, I'll be sure to report back. William R. Monroe On Fri, Jul 30, 2010 at 10:13 PM, Don Mannino <donmannino at ca.rr.com> wrote: > William, > > > > A few thoughts if I may, since the basic specs in the Boston action are the > same as the Kawai: > > > > - Dip of .400 is pretty much the same as normal 10.2mm spec, so > that’s fine. > > - Blow of 46mm is normal > > - Key balance hole is probably too loose, allowing the key (and > it’s lead weights) to bounce up off the balance rail. This bounce can > coincide nicely with the return of the hammer, sending it back up with more > energy than the hammer alone. To test this, place a finger firmly on the > key button just behind the balance pin and do the Staccato blow. If this > reduces the hammer bounce, you have a solution. Make the balance hole > tighter, so that is will SLOWLY drop back to rest position instead of freely > falling. > > - Balance rail bedding keyframe should be rechecked as well > > - Hammer rest felt should be about ½ the hammer shank thickness, > so you may have it correct already. > > - Hard back rail cloth could contribute. > > - Very loose hammer centers might contribute as well, but I > wouldn’t consider that the prime cause. > > > > As Ron said, if one tries to make an action do this, one can usually make > it happen. But it really shouldn’t show up when playing music. Check the > balance rail holes – that’s my best guess as to the primary problem, and set > the hammer line a little lower along with resetting the hammer rest > (rebound) rail to match. > > > > Don Mannino > > > > > > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/pianotech.php/attachments/20100730/3c2553c2/attachment.htm>
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