jack in the mortise

[Dave Nereson]

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  ----- Original Message -----=20
  From: daniel carlton=20
  To: pianotech@ptg.org=20
  Sent: Monday, January 12, 2004 8:36 PM
  Subject: jack in the mortise


  i have a question regarding centering the jack in the mortise (using a =
hammer tap on the head of the jack).  do the jacks need to be positioned =
in the exact center of the mortise or can they get away with being =
off-center?
  another question.  it seems that bending the center pins like this =
sometimes causes resistance toward the end of the jack's travel.  this =
concerns me because it seems that it can affect the regulation and feel. =
 is this just my imagination.  is it any big deal?
  any info and advice is greatly appreciated.

  thanks

  daniel carlton

      It doesn't have to be precisely in the center, as long as it's not =
rubbing the side of the "window".  Yes, bending the pin can cause =
resistance in jack travel and no, it's probably not a big deal for your =
average piano player, but for fine regulation of fine grands, it might =
be.  And for this reason some techs recommend straightening the =
repetition lever post instead.  It's claimed that this is what causes =
the jack to rub the side of the rep. lever window in the first place.   =
The rep. lever post dries out and warps, or twists slightly as the wood =
ages or acclimatizes, and then the rep. lever is no longer exactly =
parallel above the wippen body. =20
       I don't know how one goes about straightening those posts -- pull =
'em off and re-glue 'em?   --heat 'em up with a heat gun and try to =
twist them?  They're pretty thick -- I haven't tried straightening them =
as I don't know an effective method for doing so.=20
      Anybody else?
      --David Nereson, RPT 
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