Key dip

[Mike Bratcher]

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Before I would go and start sanding the key bottoms, I would try and =
"unshim" the balance rail.  Typically pianos of this vintage would shim =
the balance rail "universally" to get the keys in the ballpark.  Then =
they level keys from there.  This is how I usually raise the key height =
on older pianos that have excessive lost motion.

Mike Bratcher
  ----- Original Message -----=20
  From: Alpha88x@aol.com=20
  To: pianotech@ptg.org=20
  Sent: Thursday, November 06, 2003 11:19 PM
  Subject: Re: Key dip


  Clyde,

          In my experience at school, there was a similar problem in a =
studio upright in one of the rooms at school. There were no punchings =
that could be removed except the the cloth ones from under the balance =
rail. Our teacher suggested that the key itself may have swelled from =
moisture and never shrunk back and the whole key lever may be a slight =
bit bigger (hence sit higher on the balance rail than originally made =
to).=20
          We took about a 150 sandpaper and sanded off a slight bit to =
bring the key back down. It worked. But we only sanded a few =
thousandths. When one sands, the bottom of a key, it must be sanded a =
bit, put back tested then removed, sanded a bit more, checked again and =
one has to keep repeating the process until the desired height is =
achived (Just a possiblity) Does this make sense?

  Julie
  Reading

           =20
  In a message dated 11/6/03 6:33:33 AM Eastern Standard Time, =
cedel@supernet.com writes:


    Friends,

    While tuning a 1980 Wurlitzer studio piano today I noticed some of =
the
    bass hammers would damp the strings depending on how they were =
played.
    Letoff was fine, but there was too much keydip, resulting in the
    backchecks pushing the hammers into the strings after letoff.

    It appears to me that all other specs will be in the correct range =
if
    the keydip is reduced.  Can this be done by shimming up the front =
rail
    of the key frame, if there are no shims to remove from under the =
balance
    rail?  I've never tried this.  I could put card punchings under all =
the
    front felt punchings, I know.  Advice?

    Regards, Clyde





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