Yeah, It's not double striking like Let-off/drop bobbling. On a firm Stacatto, I can watch the hammer "bounce back" from what appears to be rest position - checking really is not coming into play and neither would I see a reason to suspect the tail shape. Leading pattern in the keys is pretty normal 3 and a half in the bass, tapering up evenly. Yes, about 1/16" let-off, about 1/16" drop. After touch was huge prior to me regulating it (key travel was around .430" - yes, really), and the problem didn't change when the regulation specs were changed. There is some aftertouch, but not excessive - some rise, but certainly not back to the strings. Ed, why do you think 1 3/4" and .400" is markedly out of the normal range? Just curious. I find that this amount of key travel is on the wider side, but still workable with 1 3/4" blow in a lot of actions. Didn't get to measure the action ratio or strike weights. William R. Monroe On Thu, Jul 29, 2010 at 9:20 PM, Ed Foote <a440a at aol.com> wrote: > > William Monroe wrote: > > > Hi List, > > > > > > Anyone know of anything chronic in Boston Grands (GP178) that has the > > > hammer double striking on a quick/firm staccato blow? I've got one > > > that does. Anyone have any ideas/solutions? The piano is finely > > > regulated otherwise (just today, in fact). 1 3/4" blow, about .400" > > > Key Travel, Checking about 1/2", Rep springs are definitely NOT > > > jumpy. In all other ways, the action plays nicely, controllably. And > > > that is no mean feat. I took some DW/UW measures today out of > > > curiousity, and they were haywire. DW range from 62g - 46g, UW from > > > 18g to 35g or so. > > > > > > My thoughts are turning to action pinning (haven't checked yet). Key > > > Bushings and pins are clean and lubed (teflon), but that's as far as > > > we got. Wondering if tight pinning (of any parts) might contribute to > > > this rebounding back into the strings - and it is a full rebound. You > > > can watch the hammer appear to bounce off the rest rail, though I'm > > > not convinced that is exactly what is happening. Kind of musing aloud > > > here.............. > > Double striking? That usually is a let-off problem, however, on a staccato blow? I am not sure. Do we assume a1/16" let-off with a > > normal drop? What about after-touch.? > > On a simply firm blow, this could be a checking problem, so examine the tail radius and finish as well as the back-check angle. However, > > a staccato blow, checking doesn't enter into the equation. > > Your measurements seem to indicate that there is a pinning problem, but I don't readily see a connection. I can imagine if the rep > > pinning was extraordinarily tight, the springs would be way too strong, thus making the hammer's behaviour odd. > > . If the keys are overly heavy, that can contribute, but in a cookie cutter piano like the Bostons, I wouldn't > > start with the keys. The combination of blow with dip is strange, I would assume that there is a really low action ratio, or really heavy > > hammers. > > I think we could use some more info. > > Regards, > > > Ed Foote RPT > http://www.uk-piano.org/edfoote/index.html > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/pianotech.php/attachments/20100729/e099a93a/attachment-0001.htm>
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