Thanks Jim - that makes total sense! I attended Jack's class at last year's convention and it was very helpful. I halfway "turbo-charged" some Perzina uprights that had the same problem - I reduced blow distance, but I didn't tilt the action back, and even that much helped a lot. Maybe if I did the rest of the procedure it would have helped even more! The flange repinning has been successful for me too. I shy away from changing damper spring tension because a good technician did this on a whole slew of local institutional pianos to solve the problem, and next thing you know I had to undo it because the dampers were leaking! Just to clarify, in every flange that bobbled I was getting 10+ swings of the hammer, but I only repinned them to get them within a normal range of swings - nothing that would create "other problems" in the action. Also, I have never repinned an entire set of flanges; I only repin the 6 or 8 notes that have the bobbling problem. I've never serviced a Chinese upright that had more than a handful of bobbling notes, so it wasn't that big a deal to repin them. Scott ------ Scott A. Helms, Registered Piano Technician www.helmsmusic.net > All, > > Can I throw something else into the mix? Last year I posted a similar > problem on CAUT and got a lot of the same advice. Lot's of good advice, > great advice, for the "normal" or typical resolution of double striking. > However, nothing solved it completely. > > It was the same make as Britney's piano, and I tried everything. The real > problem seemed to be in the design, or at least the implementation of it, > whether right or wrong. (i.e. The design may have been good but the > gorrillas in the factory missed it.) If the hammer assembly doesn't tend > to "lean" (for lack of a better word) back so that the center of gravity > favors a return, it sometimes ends up double bouncing more. The Chinese > pianos use the Schwander type return spring, which is considerably less > strong than the American spring. The weaker spring can't overcome too much > of this gravity thing. If the hammer isn't raked enough, and/or if the > hammer assembly/action (balance) set up is not favoring a return this > problem seems to be exacerbated. On my piano strengthening the return > spring helped, but there was something else. > > With my piano I experimented by physically leaning the piano forward > (toward the player, slightly) and the problem went away. So... what I > ended up doing is "Turbocharging" the piano a la Jack Wyatt. I won't post > this exact procedure here since Jack might not like that, but maybe it's > been posted before. It consists of tilting the action forward (out, spacer > washers) then reregulating blow, etc. > > FWIW, that's what did it in my case.. > > Jim Busby >
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