action reg puzzler on M & H BB

R.Moffatt & Sons Piano moffatt5 at telus.net
Mon Sep 25 11:56:50 MDT 2006


  Sounds like the backcheck wire is loose in the key. After repeated blows it will change.

  R.Moffatt & Sons
  Piano Technicians
  2323 Lincoln Drive S.W.
  Calgary, Alberta ,  Canada T3E 5G4
  Phone. 403.243.0385
  www.moffattpianos.com
  Fax.     403.243.6821
  email:   moffatt5 at telus.net








------------------------------------------------------------------------------
  Original message
  From: "Mark Potter" 
  To: "Pianotech List" 
  Received: 09/25/2006 11:08:06 AM
  Subject: action reg puzzler on M & H BB


  List -

  I am having a puzzling problem with a M & H BB grand action that I have never encountered.  Complete regulation (w/new shanks& hammers), everything works great with the exception of 3 notes - F6, A#6, G7 -  in the high treble.  I cannot get this to happen on the bench, and even in the piano when the notes are played softly, even in a trill, they perform perfectly.  However, under continuous mf - ff blows, as in tuning, after anywhere from 1 to 10 strikes (letting the key all the way up), the hammer will get caught on it's way back up by the back check, thereby not allowing it to strike.

  I have tried numerous adjustments to the angle of the back check as well as to the height of check for these 3 notes, to no avail.  Everything seems to be identical to the surrounding notes, including jack reg - both in the window and to the knuckle core -, rep spring strength, key dip, stroke, the arc of the tails, let-off, drop, etc., etc... you name it.  Keys are rebushed and moving freely.

  If anyone can shed some light on this puzzler I would be most grateful!!

  Mark Potter  


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