Music Trade Review

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TECHNICAL^SUPPIY DEPARTMENT
William Br aidWhitefec/imcal Editor
The Necessity for Absolute Accuracy
and Correct Scale Design in the Piano
Replies to Two Questions Which Are Often Asked in the Piano Industry and Which Have
Good Basis for Being Asked—The Possibility of Accuracy in the Use of the
Decimal Scale and Its Value to the Scale Draftsman and Piano Builder
T
WO questions are often asked by prac-
tical men who have listened to talk about
scientific method in scale drafting. One
is, in effect: "Why calculate string lengths to
less than one-tenth of an inch, when the best
efforts of the bellyman are almost certain to
introduce a larger error?" The second one is:
"Why place so much stress upon a correct scale
design when the best pianos on the market
have been developed more by patient experi-
mentation on soundboards, hammers, action
work and tone regulating, than upon anything
else?" or words to that effect.
These are not idle questions. They are often
asked by men who have no wish at all to throw
cold water upon any man's honest attempts at
accuracy. Those who ask these questions are
looking solely for information. They realize
that the argument for scientific method is very
powerful, for they are aware that the piano in-
dustry has been technically in a static condition
for many years, whilst other industries not
otherwise any more advantageously situated
have gone steadily forward along the road of
improvement. Yet these men also find that
their experience sometimes contradicts the
claims of the proponents of scientific method.
They have experimented with many scales and
always have found that they have to do an im-
mense amount of work on them before they can
make from them instruments satisfactory to the
ear. Thus they feel that they have a good right
to demand of the scientific man that he prove
what he alleges.
• Personally I never object to these challenges
and in the present case am more than willing to
try to answer the two typical objections I have
quoted; for they are insistent and cannot
rightly be ignored.
The Possibility of Accuracy
At a meeting of the Wood Industries Divi-
sion of the American Society of Mechanical
Engineers, two weeks ago, a paper was read on
sash and door manufacturing. In the course of
it the engineer, who was its author, remarked
that the machines he was describing were far
more accurate than most of the machinery used
in machine shops. He gave evidence in sup-
port of this rather surprising thesis and showed
that modern wood working machines are
amazingly accurate in their construction as well
as in their performance. On the other hand,
wood workers still talk and think as if the error
range in wood-working operations were always
and inevitably very large. It is true that wood
is a refractory material, in the sense that its
susceptibility to the influence of moisture,
whether atmospheric or artificial, renders it
variable in respect of dimensions. Rut it is also
true that wood-working has been steadily be-
coming more accurate during the last twenty
years. Any one who is acquainted with the
methods which prevail in most piano shops
knows that accuracy in following given meas-
Punchings
Washers
Bridle Straps
581437th Ave.
urements could, in most cases, be vastly in-
creased.
The Object of Accuracy
Now the object of closely calculating the
lengths, of strings is to obtain the greatest pos-
sible accuracy in the fitting of bridge and plate,
to the end that the actual lengths appearing on
the completed piano may be as near as possible
to being absolutely accurate. By very closely cal-
culating the lengths, after having arrived at a
proper basis for the calculation, we are able to
set out a pattern for the plate maker, and also
for the patternmaker who is to give the belly-
man the bridge and the drilling jig for it, with
which these latter mechanics may be able to do
their work as it should be done. I am quite sure,
from actual experience, that the longest strings
can be laid out within an error not exceeding
.05 inch, when the bridge pattern has been prop-
erly followed in making the bridges and in drill-
ing them. When these two last-named points
have been properly attended to, the bellyman
has only to make sure that he gets the proper
length of string at the first and last unisons on
each of the two bridges, treble and bass. Nor
is there any good reason for any error larger
than 1/16" ( = .0625") at the worst, which, on
short strings, can be reduced to less than half
this much.
Value of Accuracy
What then is the use of such accuracy? In
the first place, if one calculates every string
length to the second place of decimals, one
may always be sure of measuring distances with
an error not exceeding .02", merely by being
careful always to use a decimal rule. I have
for long used such a rule, made of steel and
graduated to l/100ths of an inch. By using a
pair of dividers with sharp points, there is no
.difficulty in coming within one division of the
scale, plus or minus. The prick mark one makes
on the paper when the point of the dividers is
pressed down need not be more than .02" in
diameter. It is, in fact, just as easy to work to
a decimal scale, attempting to measure within
an error not exceeding ± .02", as to work to
thirty-seconds. And there is the added advan-
tage that one is far more often able to land
square on the exact length. In fact when a
EASY TO REPAIR
DAMAGED FINISHES
Y
OU can easily repair the damage
to varnished surfaces through fol-
lowing the instructions given in our
book "How to Repair Damage to Var-
nished Surfaces." Dealers everywhere
are enthusiastic over the ease with
which this is done—and the losses
which have been eliminated. A copy
will be sent to you free upon request.
The M. L. Campbell Co.
1OO8 W. 8th St.
Kansas City, Mo.
George W. Braunsdorf, Inc.
Direct Manufacturers of
TUNERS' TRADE SOLICITED
Also—Pelts and
Cloths, Furnished
in Any Quantity
Woodside, L. I., N. Y.
35
length is expressed by some number of which
the fractional part is .05, .10, .15, .20, .25 or
others of that order, one can be certain of land-
ing upon the exact point on the scale without
any trouble. The decimal scale in fact pro-
motes practical as well as theoretical accuracy.
Effect on Results
A second reason for insisting upon calcula-
tions more accurate than can always be carried
out is to be found in the fact that the bridge
curve always comes out more nearly as it is in-
tended to be, when the plotting of lengths is
done to the limit of accuracy on the decimal
(Continued on page 36)
Our large stock is very seldom
depleted, and your order, whether
large or small, will receive imme-
diate attention. In addition, you
get the very best of
Felts— Cloths— Hammers —
Punchings — Music Wire —
Tuning Pins—Player P a r t s -
Hinges, etc.
We have in stock a full line of
materials for Pianos and Organs.
The American Piano Supply Co.,
110-112 East 13th St.
New York City
William Braid White
Associate, American Society of Mechanical
Engineers; Chairman, Wood Industries
Division, A. S. M. E.; Member, American
Physical Society; Member, National Piano
Technicians' Association.
Consulting Engineer to
the Piano Industry
Tonally and Mechanically Correct Scales
Tonal and Technical Surveys of Product
Tonal Betterment Work In Factories
References
to manufacturers of unquestioned
position in industry
For particulars, address
209 South State Street, CHICAGO
Piano Technicians School
Courses in Piano Tuning, Regulating and Repairing.
(Upright, Grand, Playar and Reproducing; Pianos.)
Professional Tuners have taken our courses to
broaden the scope of their work. Write for Catalog R.
Tat T. M. C. A. «r Philadelphia, 1421 Area Street