dangerous pianos

[Delwin D Fandrich]

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  ----- Original Message -----=20
  From: Dave Nereson=20
  To: pianotech@ptg.org=20
  Sent: June 19, 2003 11:51 PM
  Subject: Re: dangerous pianos


      A technician friend of mine showed up to tune a grand and noticed =
all the plate screws were missing.  He asked the owner about it, who =
said, "Oh, I took them out to have them re-plated."  Needless to say, he =
didn't raise pitch or tune, but just waited til the screws were =
returned, then reinstalled them.  Nothing bad happened, (not to say it =
never could).=20
      --David Nereson, RPT

This subject line does bring up the interesting question of just what =
the "plate bolts" actually do. And how much stress from string tension =
is actually born by the rim. In pianos such as the Steinway in which a =
horn is used as a gap-spacer some string tension is deliberately =
transferred to the bellybraces. In all others (grands, that is) the =
plate is designed to support all of the string tension without the aid =
of the rim. The plate bolts are there to suspend the plate, to fix the =
plate to the rim and keep it from rattling around inside the rim and to =
keep the plate stable and prevent undo twisting and flexing.=20

Removing all of the plate bolts for plating, while certainly not =
recommended, probably did not increase the stress load in any part of =
the plate enough to be dangerous. This is especially true with short =
pianos. The reason the practice is not recommended is that there are a =
few under-designed plates out there that just might already be marginal =
and a bit of extra twisting and flexing would be enough to take them =
over the top.=20

But, as to their being dangerous to life and limb, they are not. Some =
factories break plates on a more-or-less regular basis. (OK, not every =
day, but often enough that it is not a really big deal when it happens.) =
What happens when they break is they break. A crack develops somewhere. =
Usually with a nice, resounding bang that draws everybody's attention to =
the thing but nothing goes flying anywhere and nothing explodes.

Del

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