String Scaling stratagy

[Ron Nossaman]

Hi gang,

Forgive me, but no one's posted anything truly aggravating for at least a
week, and I can't stand it any longer.

Cruising the exhibition area at Arlington, I stopped at the Fazioli booth
to play with the action model with the mag-lev retrofit, and scooped up
some of the offered general literature about the pianos while I was there.

In the brochure that tells me all about the magic resonant spruce trees
from the forests of the Fiemme Valley, I came across a page that looked for
all the world like a stringing scale spreadsheet printout for the model
F.308. Being of a somewhat debatable degree of soundness of mind, I went up
to my room shortly afterward, fired up my laptop computer, did a few quick
and dirty modifications to my scaling spreadsheet to accommodate the data
format, and ran as much of the scale as was printed in the brochure just to
see what it might tell me. This, at long last, brings us to the purpose of
this post. For those of you out there who also do rescaling, I have an
observation or so, and a similar number of questions. 

Scales that I've taken from current production pianos seem to favor
blending and smoothing the differences in core break% between the
monochords and bichords, and the wound bichords (or trichords) and plain
trichords, at the expense of tension and impedance curves. Technicians'
rescaling efforts (those I've seen) seem to tend more toward either trying
to strike a balance between the tension and impedance, and break%, or
ignoring break% altogether. I'm ignoring the inharmonicity curve because
you can do about anything you want with it if you don't mind jagging up
something else, so it's neither here, nor there for this bit. The various
stretch factor formulas I've seen indicate that the stretch% is related to
the break% so that the higher the break% tension, the less pitch change
will result from any given elongation change.

Ok then, here's the question. To the rescalers among you, not getting into
relative wrap proportions, length/diameter, and such, how much attention
and weight do you give jumps in the core break% at the transitions between
wound mono/wound bi, wound bi/plain tri, or combinations involving wound
tri - if you support such notions? 

Ron Overs has mentioned on the list that he takes break% into account for
tuning stability at scale breaks, as well as trying to keep low tenor
break% high enough to minimize the low tenor "tubbies". Other techs have
mentioned the low tension, low tenor "tubbies" as well, but not in the
context of break%. 

Any thoughts anyone would care to trot out along these lines?

Ron N