<HTML><HEAD></HEAD> <BODY> I had a Yam C7 that would be wildly out of tune= every few months.  Yamaha recommended letting down the= tension and tightening the plate/pinblock screws.  I did= this and the screws turned about an 1/8th of turn.  The= piano has been solid since...15 years or so.  Consider at= least snugging the plate screws and plate/pinblock screws even= if you don't let down the tension.  Check the bridge/string= seating.  Who's tuning this?  You or the= apprentice? David I.     ----- Original message= ----------------------------------------> From: jolly= roger <<A= href="mailto:baldyam@sk.sympatico.ca">baldyam@sk.sympatico.ca</A= >> To: <<A= href="mailto:pianotech@ptg.org">pianotech@ptg.org</A>> Rec= eived: Thu, 15 Aug 2002 02:10:44 -0500 Subject: Re: Flag= poling Petrof pins? Hi= Ron,          &n= bsp;    I would not be surprised if there was a= poor pin block to flange fit.  Particularly if it's a newer= instrument. Regards Roger At 09:52 PM 8/14/02= -0500, you wrote: <BLOCKQUOTE class=cite cite="" type="cite">I don't have any= information specific to the Petrof, but in general... <BLOCKQUOTE class=cite cite="" type="cite">Stability seems to be= a problem.  This piano has an open faced pin block which= means that the pins stand upright and do not lean back as in a= conventional design.  The coils stand 1/4" - 3/8" above the= block.  The hypothesis is that the pins may be bending= excessively due to the high coils, making setting the pins more= difficult. A possible cure would be to simply set the pins= deeper into the block,  although this is speculative= theory, (particularly since this is how it was designed). = Additionally this would add friction to the pins which may= contribute or create a new problem.</BLOCKQUOTE> I wasn't= aware that open face meant the pins stand upright instead of= leaning back, but there are a lot of things I don't know and= that isn't the problem in any case. Is the problem really with= tuning stability, or getting a solid tuning in the first place?= These are entirely different things, and driving pins won't= improve tuning stability. It will, however, give you a little= better control for getting the string settled in. An open face= block with the coil 3/8" above the block shouldn't tune any= differently than a piano with a non-bushed plate with the coil= 1/8" above the 1/4" thick webbing, so if you don't= characteristically have trouble with that very common type, the= Petrof shouldn't be a problem either - unless that's not the= problem. How tight are the pins already? What's unstable about= the tuning? Unisons, overall pitch drift in certain specific= areas? Do the strings render well across the bearing points= while you're tuning? Hot lights? Ron= N </BLOCKQUOTE> </BODY></HTML>