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<p>Ron Nossaman wrote:
<blockquote TYPE=CITE>>A couple questions here... I know several guys who
routinely use a scaleing
<br>program
<br>>to redesign the scale when restringing / rebuilding. These fellows
<br>typically are
<br>>repairing cracks in the soundboard (shimming). They take care to check
<br>"downbearing"
<br>>before and after lessening tension on the strings. Often they lower
the
<br>plate a bit
<br>>(something I question the reasoning for ... read Ed McMorrows book).
<p>* Doesn't anyone ever check the crown under load? That is, before lowering
<br>string tension? By my way of thinking, if there is little enough downbearing
<br>to necessitate lowering the plate, there had better be adequate crown
in the
<br>board to take the load or the board will be driven flatter, or farther
past
<br>flat, than it already is. Increased bearing angles = increased soundboard
<br>load, and if the board is already flat... where's the fix?</blockquote>
Exactly my point. Personally, tho not an accomplished rebuilder myself,
I have not seen a soundboard that has both too little downbearing and at
the same time plenty of crown.
<blockquote TYPE=CITE>
<p>* You didn't mention checking crown either. Do you? Also, I wouldn't
worry
<br>too much about sneaking up on the tension. Just chip and rough tune
to pitch
<br>immediately after stringing and keep it there while it settles in.
<p> Ron N</blockquote>
Hmm.. I guess I need to be more precise. String deflection at the bridge
is measured before easing off string tension, and then again afterwards.
The difference gives a reading of how much the board rises with tension
off. ie. crown. Does this jive with your meaning of crown ? If not I would
like to hear how you check crown.
<p>This is in any case what is done here in Norway by most of the fellows
doing rebuild work. And as I said in my last, they use this info most often
to decide how much they are going to <i>lower</i> the plate by. I have
never heard of anyone over here even think about raising the plate. (grin..
except me)
<p>What makes me scratch my head about this is that these two measurments
only give a picture of the present condition of crown. If a rebuilder increases
the press downwards by lowering the plate, with only this bit of info at
hand, then this seems to me to be an uninformed "choice" unless he / she
knows how much crown there was when the piano was new. Does this make sense
?
<p>Richard Brekne
<p>I.C.P.T.G. N.P.T.F.
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