Couldn't you raise the hammer rail with a punching (for experimenting!) and take up the lost motion on a sample and see if the jack escapes? Seems to me the simplest solution. Easier than altering the dip. The jack return spring isn't puny in any case... David Ilvedson, RPT Pacifica, California ----- Original message ---------------------------------------- From: "Annie Grieshop" <annie@allthingspiano.com> To: "Ric Brekne" <ricbrek@broadpark.no>, pianotech <pianotech@ptg.org> Received: 11/2/2005 8:04:01 PM Subject: RE: Yamaha jumping jacks >Howdy Ric, et al., >The jack tops did appear to be unreasonably close to the butts, which I >wondered about. And, yes, the double-strikes are a soft-blow phenomenon. >But I could feel the hammers wobbling when I played before starting tuning, >and I'm not about to leave customers with that, even if they'd never >recognize (or probably even notice) the wobble. I thought the jack return >springs looked pretty puny, but maybe looks are deceiving in this case. >When did Alan deal with these issues in older instruments? I haven't seen >any such reply to my query, so I'm wondering whether I missed something (as >usual <g>). >Thanks! >Annie >> -----Original Message----- >> From: Ric Brekne [mailto:ricbrek@broadpark.no] >> Sent: Wednesday, November 02, 2005 12:11 PM >> To: pianotech >> Subject: Yamaha jumping jacks >> >> >> Hi there Annie >> >> If these are new pianos, and the action is reasonably well regulated >> then my first guess is always too strong jack return springs and / or >> too strong damper springs. Both tend to leave the jack top just a tad >> too close to the butt. A clue that these springs are involved is that >> the double strike goes away if you insure a very firm bottoming of the >> key stroke. >> >> On older instruments, lots of things can come into play. Alan delt with >> most of that nicely. Tho I would add that the jack stop rail on >> occasion can also need adjustment. >> >> Cheers >> RicB >> >> Annie Grieshop wrote: >> >> I had two tuning jobs yesterday that involved relatively new Yamaha >> verticals - an M500 and an M450. Both have very jumpy jacks (or, >> at least, >> that's my analysis of why they're tending to double-strike, even when >> well-regulated), and I'm wondering why. >> >> Both have plastic jacks and synthetic buckskin. The M500 had been treated >> with something that looked graphite-like and was less jumpy than the M450, >> which leads me to believe that the proper lubricant (or other treatment) >> might solve the problem. I would very much appreciate any >> suggestions as to >> how to proceed. Thanks! >> >_______________________________________________ >pianotech list info: https://www.moypiano.com/resources/#archives
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