How does one determine the original designed pitch?

[Joseph Garrett]

Clair,
Actually, it's a crap shoot. But, having said that, the establishment of
A=440cps came about in the 1920's. Prior to that, I SUSPECT, that a lot of
those who were actually doing scale design, were actually using it as a
criteria. However, there were those who chose to "label" their pianos as
being designed to "International Pitch A=435cps". The classic designer of
this is Chickering. Be aware that the written wire size on the plate is not
necessarily correct, as some time around the turn into the 20th century, the
steel industry CHANGED the number designations of piano wire! This is
evidenced in several books, the most common is William Braid White's Books.
If you refer to them, you will note that the wire size(s) are off by .001"
from what we know as "number" vs "mil" size.
IMHO, anyone who is rebuilding any piano, should ALWAYS do a scale
evaluation, using a program that will allow you to total the tensions of the
sections, show appropriate graphs and allow different Pitch Standards to be
used. This, plus actual observation of the physical mass of board, plate,
back assembly, etc., should give you some clues as to how the piano should
inevitably be scaled. One thing that really pushes my "hot" button, is for a
tech to arbitrarily drop all the wire sizes down .001"! If anyone of you do
this, please stop and get a computer program. Otherwise, get a qualified
scale designer to help you. There are many techs that do this, on a regular
basis. I am one. (commercial time<G>)
Regards,
Joe Garrett, RPT, (Oregon)