At 03:10 PM 8/21/98 -0700, Jim Coleman, Sr. wrote: >I have seen centerpin plating flaking off on Yamaha, Kawai and Korean >pianos. No amount of shrinking solution will help this situation. Repinning >is the only option. I have looked at the ends of thes pins under >microscopes. There is a definit scoring around the pin ends. One technician, >deceased, had suggested that the silicon in the factory treatments had >turned back into glass and had therefore been the cause of the scoring. At >the time it made sense to me, but I have not proven this theory. If it were >true one would expect to see granules of glass in the bushing cloth. Others >have suggested that the hide glue wicked into the felt and caused the >scoring. I have never seen this phenomenon on american made piano actions. > >Jim Coleman, Sr. ------------------------------------------------------------ Hi, Jim Glad you have confirmed what I found. I always assumed it was the fragments of the plating, lodged in the bushing cloth, that were doing the scoring. Nickel is harder than brass, isn't it? (or is it?) The scoring was plainly visible using just my reading glasses. It must have been spectacular through a microscope. The worst of these pins _squeaked_ as one forced the flange to rotate. On the other hand, repinning with a little reaming, using unplated center pins, has always worked for me. Maybe the fragments fell out? But I never saw them. They had to go _somewhere_, though. Someone should remove the cloth and look at that under magnification, and see if fragments of plating are wedged into the cloth. The next time I come across one of these pianos I will. I have a friend who teaches chemistry at a community college. I can use one of their microscopes. I wonder if there might be a bad interaction between some chemical used in dying or sizing the cloth and the plating, or if they just had a few bad batches of poorly plated center pins. It must be miserable to manufacture a ton of pianos, and then several years later learn that some of your materials were substandard. No way to know until they've been played hard for a couple of years. Kind of like Baldwin's corfam nightmare. I credit this time and information lag for allowing designers to have other illusions, such as that teflon is noiseless in trapwork fittings or sprayed on damper flanges and hammer butts (to replace spring punchings.) I had also heard of center pin plating failing in Yamahas of an earlier vintage, especially practice room grands seeing heavy use. I've encountered it in DaeWoos, though nowhere as badly as in several Samick grands of about 1990 vintage. Someone told me that Yamaha stopped using the plated pins because of it. Someone else said that the only reason to use the plated pins is because they work better with some of the machinery doing the pinning. Complete failure of about 1/4 of the center pins in some of their pianos seems a heavy price to pay for this convenience in manufacturing. For some reason, I've only seen it in grands. Do you know if the pinning is different in uprights? Or have I just been lucky? I don't know why our friends back east haven't found this happening to (_some_, not _all_) Samicks, except that maybe the Samicks there also suffered from more normal dampness-related tightness, and the centerpin problems went unnoticed. They treat so many actions. We're spoiled, out west. Best wishes, Susan ----------------------------------------------------------------- > > >On Thu, 20 Aug 1998, Richard Moody wrote: > >> >> >> ---------- >> > From: Susan Kline <skline@proaxis.com> >> > To: pianotech@ptg.org >> > Subject: Re: Re: Samick (again) >> > Date: Wednesday, August 19, 1998 5:52 PM >> > >> > List, Richard, Avery, Jim -- >> > >> > Everyone seems so sure that tight flange bushings are the problem, yet >> I've >> > never known a Samick to seize up from anything except failure of the >> center >> > pin plating. >> >> HMm If the easing methods work from lubes or shrinking solutions, I >> would never look at a c pin. Darn, on hind sight I should have "watered" >> the action on that Samick since it has been such a sure fire remedy. After >> that, the seller, who was also a technician could have re-pinned to his >> heart's content. I wonder what the content of the felt bushings are? >> >> Richard >> ----------------------------------------------------------- Susan Kline P.O. Box 1651 Philomath, OR 97370 skline@proaxis.com
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