Soundboard Torture - and Understanding!

[Delwin D. Fandrich]

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  ----- Original Message -----=20
  From: Farrell=20
  To: Pianotech=20
  Sent: Friday, April 11, 2003 4:36 AM
  Subject: Re: Soundboard Torture - and Understanding!




  > I was debating with myself as to whether or not I should warn you =
about
  > this, ultimately deciding that experience is a really great teacher =
and you
  > weren't jeopardizing any priceless pianos on your road to discovery. =
You can
  > use a spruce panel as a humidity indicator but you have to allow it =
to
  > free-float. I.e., you cannot allow it to come under compression.

  Gee whizz. Nice guy! It was a very good educational experience. Now =
how can you free-float a gauge? The only way I can imagine that is to =
not put a rib on it, and simply measure the change in length across the =
grain. Is that what you have in mind?

Ah, but Grasshopper, what you learn by doing will go into your being =
with much more clarity than what you learn by reading.

As to my idea of a wood-based humidity indicator--think in terms of =
levers.... Multiply that motion. (All of which is the sneaky way of =
saying I can't find the appropriate drawing or picture in my new =
computer. Soon! Real Soon Now!)


   > Yes, what you are witnessing is 'compression set.' This phenomenon =
takes
  > place any time wood cells are placed under compression and are =
particularly
  > observable when the compression is applied perpendicular to grain.=20

  I be a believer! I be seen it with my own eyes!
  =20
  This quickly brings to my mind the sight of several semis full of =
(compression-crowned-type) new pianos for a local "University Sale" that =
sat for a week in a blacktop parking lot in Tampa Florida in the full =
sun during the hot monsoon month of July. Not a pretty thought.
  =20
  Is it possible this had anything to do with the negative 1/4" of crown =
in MY new "famous NY manufacturer" piano?
Partly, yes.


   > Keeping a piano with a compression-crowned soundboard in a =
hermetically
  > sealed environment would not relieve the problem unless the =
atmosphere in
  > the hermetically sealed environment were maintained at such a level =
as to
  > keep the soundboard panel at 4% MC.

  Does a semi in an August Florida monsoon meet this criteria?
I don't know. What are the numbers?

Del

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