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<p>Ron Nossaman wrote:
<blockquote TYPE=CITE>
<p>* They're out there. I've seen negative bearing on a board with about
6mm of
<br>crown at the longest rib, and between 2 and 3mm in the killer octave.
It
<br>looked like the plate had just been set too high in the first place,
and
<br>lowering it a little should work wonders in that piano. If it was one
of
<br>those where the tension could be dropped and the plate, pinblock, and
<br>strings could be lifted out as a unit, it wouldn't have been that hard
to do.</blockquote>
<p><br>This has <u>gotta</u> be on cheap pianos.. or what ???
<blockquote TYPE=CITE>
<p>>Hmm.. I guess I need to be more precise. String deflection at the bridge
is measured
<br>>before easing off string tension, and then again afterwards. The difference
gives a
<br>>reading of how much the board rises with tension off. ie. crown. Does
this jive with
<br>>your meaning of crown ?
<p>* Yes, sort of, but I meant crawling underneath with a string and
<br>flashlight, stretching the string from rim to rim against the underside
of
<br>the board - parallel to and between two ribs. The gap between the string
and
<br>the board in the middle is the crown.......</blockquote>
Ah... yes.. well we do this with a long straight edge that can be moved
around a bit on the underside of the board to check for flat spots and
get a general picture of the shape of the crown and how much there is under
tension. It is my understanding that as long as this is in good shape,
and there is a noticeable difference in the string deflection readings
at the bridge before and after tension is let down, then the board is worth
fixing. This much I can do.
<p>What I <u>dont</u> do is routinely lower the plate as part of such repairs.
If I run into one of the pianoes you mention above I suppose I will have
to, but most of the time I run into either reasonably ok boards, or ones
that are just to far gone to do anything about.
<p>But what I'd like to be able to do is learn more about this buisness
of how ribbing, soundboard frequency modes, stringing scales and other
such considerations inter-relate. Until I do I am never going to really
get to do much more then "filling cracks" without screwing the piano up.
(a bit overstated, but you get my point) Finding written info on this is
at best...er.. difficult and time consuming. I'd love to take a couple
years off and go work for somebody like Del, but well I gots to make a
living donts I.. grin.
<blockquote TYPE=CITE>
<p>I hope this makes sense. I'm pretty helpless at trying to explain most
<br>things without pencil and paper, and lots of hand gestures (gesticulating
<br>wildly, occasionally scratching, often befuddled).
<p> Ron N</blockquote>
<p><br>Grin.. Me thinks ya does fine. Thanks to both you and Del for following
up on this one. Del, I do hope this book of yours is like out of the "how
am I going to start" phase and more into the "I need a publisher", grin.
I aint getting any younger. :)
<p>Richard Brekne
<br>I.C.P.T.G. N.P.T.F.
<br>Bergen Norway
<br>
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