Old Upright, partial plate, Pitch?

[Dave Nereson]

  ----- Original Message -----
  From: Mike and Jane Spalding
  To: pianotech@ptg.org
  Sent: Wednesday, August 08, 2001 10:49 AM
  Subject: Old Upright, partial plate, Pitch?


  List,
     Can a partial plate upright be safely tuned to 440 or should it be kept
at, say, 435?

  Although "standard" pitch was the so-called "International Pitch" (435)
when many of these old uprights with 3/4 plates were built, I have raised
many of them up to 440 as long as I had a good feeling about the piano being
able to take it (not scientific, I know) AND:  I tightened plate screws
first, inspected for integrity of pin block, and no separation of plate or
pinblock from the back, inspected for rusty strings & pins, strings that
have been spliced or replaced, advised owner of risks, and preferably filed
& reshaped hammers and regulated at least lost motion and let-off first (to
give the hammer a firmer blow to the string to "get it vibrating real good"
to render through the bridge pins.  In 22 years of tuning, I've had only 1
old upright "give way", that is, the soundboard "broke" somewhere, I
guess -- I couldn't find anything obvious, but it sure made a big bang.
Held pitch, though, and still sounded OK.  Soundboard and bridge damage or
failure, and strings breaking, are more likely than the plate cracking, but
anything can happen, and apparently it's more risky with a 3/4  plate, which
is why Wim and others don't do it even with a full plate.  But I remember
somebody else in this list saying, "440 or die!"  Probably better to err on
the safe side and leave it low.
    The exposed pinblock itself shouldn't be of much concern; some verticals
with "full plates" have large openings for the tuning pin "fields" rather
than individual holes drilled through the plate.
      To the calculating techs out there:  what's the total tension
difference on the plate between a piano tuned at 440 and one at 435 (for a
typical scale design of an old upright)?   And what's the difference in the
total downward pressure of the strings on the bridge &
board?      --Sincerely, David Nereson, RPT