IMPROVEMENTS IN THE CONSTRUCTION OF PIANOFORTES
Year: 1885

page_text: I JOHN BRINSMEAD of the Firm of John Brinsmead and Sons of Wigmore
Street W. in the County of Middlesex, Pianoforte Manufacturer do hereby declare
the nature of the said invention for IMPROVEMENTS IN THE CONSTRUCTION OF
PIANOFORTES to be as follows:-
My Invention relates to improvements in the construction of pianofortes and has
for its object, first, to dispense with the wooden bracings and framing on which the
metal string frame is ordinarily dependent to enable it to sustain the tension of the
strings, secondly, to enable the said frame, with the sounding board and adjuncts
fixed thereto, to be readily placed completely strung and with the action attached,
in any suitable case. The instrument proper is thus self contained and quite
independent of the case.
My Invention has also for its object to provide an improved means of enabling
the sounding board to be bellied or raised more or less towards the centre, as
required, for the purpose of obtaining or restoring the proper bearing of the strings
on the belly bridge so as to compensate for inequalities at different parts of the
sounding board, or for any yielding of the sounding board under the pressure of
the strings. By means of this adjustment great regularity of power and purity of
tone may be permanently obtained.
My first improvement consists in constructing the metal string-frame with a
deep flange on both front and back at each side and at bottom whereby to stiffen
it sufficiently to resist the tension of the strings without the support of the usual
wooden bracings and framework to which such metal frames have heretofore always
been fixed. The frame is also cast with supports for the key bed and provided
with means of securing the frame in its place in the case.
My second improvement consists in a mode of fixing the sounding board to the
string-frame whereby the instrument proper is rendered completely self contained
and the desired adjustment or bellying of the sound board to compensate for the
pressure of the strings is obtained. The sound board is provided with fillets at two
diametrically opposite points (for instance in an upright piano with a diagonal
fillet across the left hand upper corner and with fillets extending a short distance
along the bottom and side from the right hand corner) which fillets take a bearing
against the back of the metal string-frame, and at suitable points on the inner side

page_text: of these fillets screws are inserted which draw the sounding board towards the string
frame whereby the sounding board is bellied until the true bearing of the strings
on the bridge is obtained-Other screws are also inserted at intervals around the
free edges of the sound board to assist the above mentioned screws and render the
bellying of the sounding board uniform throughout.
COMPLETE SPECIFICATION.
Improvements in the Construction of Pianofortes.
I, JOHN BRINSMEAD, of the Firm of John Brinsmead and Sons, of Wigmore
Street, W. in the County of Middlesex, Pianoforte Manufacturer, do hereby
declare the nature of this invention and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement:
My Invention relates to improvements in the construction of pianofortes; and
has for its object, first, to dispense with the wooden bracings and framing on which
the metal string frame is ordinarily dependent for the rigidity necessary to enable
it to sustain the strains due to the tension of the strings secondly, to enable the
said frame with the sounding board (and, in the case of an upright instrument, the
action) attached to be placed completely strung and ready for use in any suitable
case, the instrument proper being thus self contained and quite independent of the
mere outside case.
My Invention has also for its object to provide an improved means of enabling
the sounding board to be bellied, or raised more or less towards the strings; as
required for the purpose of obtaining or restoring the proper bearing of the strings
on the belly-bridge, so as to compensate for inequalities in the structure of the
wood of which the sounding board is made, or for any yielding of the sounding
board under the pressure due to the down bearing of the strings. By means of
this adjustment, great regularity of power, and uniform purity of tone, may be
permanently obtained.
Reference is to be had to the accompanying drawings forming part of this
specification wherein I have illustrated the Invention as applied to an upright
Pianoforte, but I would have it understood that the Invention is equally applicable
to instruments of the horizontal, or grand, type.

page_text: Figure 1. represents a front elevation of the string frame and sounding board
with the strings and action removed.
Figure 2. is a rear elevation of the same.
Figures 3. and 4 are cross sections at lines 1-1. 2-2. Figures 1. and 2
respectively.
The cast-iron string frame a is a single casting of the general outline usual in
iron-framed instruments. It has a deep rib b, cast in one with it at top to receive
the screw-tuning pins, the rib and screw pins forming the subject of previous
Letters Patent, and being fully illustrated in the specification N° 5609 of 1884.
In order to give the string frame sufficient stiffness to enable it, unsupported, to
resist strains of flexure due to the tension of the strings, and their "down bearing"
on the sounding-board, the frame a is cast with a deep flange c projecting both
from the front and back of the said frame, and being continued entirely around the
frame except where the flange b is situated.
In the case of an upright instrument, the frame is also cast with lugs e on the
inside of the side flanges c to receive the bearers for the key bed which supports
the key-board action and pedals in position, so that the instrument is complete in
itself and is quite independent of the case. The frame a is provided with studs f
at each side, which drop into slotted plates or brackets fixed to the inner faces of
the side cheeks of the case whereby the instrument proper is supported in position
within the case, or it may be otherwise fixed.
The mode of fixing the sounding board to the string frame whereby the
instrument proper is rendered completely self contained consists in connecting the
sound board to the rear side of the web of the frame a, and within its flanges by
screws g inserted at intervals through holes drilled in the web of the frame a and
screwing into fillets h glued to the back of the sound board around its four sides,
the sound board not being drawn up tight against the frame but being entirely free
therefrom except at two bearing points or fulcra hereafter referred to in connection
with the mode of adjustment next described.
The desired adjustment, or bellying of the sound board to compensate for the
pressure of the strings, is obtained by providing the sound board with fillets
extending across two diametrically opposite portions thereof (for instance in an
upright piano with a diagonal fillet i across the left hand upper corner and with
fillets / extending a short distance along the bottom and side from the right hand
lower corner of the sound board) which fillets are glued to the front of the sound
board and take a bearing against the back of the string frame a and constitute
bearing points or fulcra for the application of power by means of screws / inserted
through holes in the cross-bars of the frame a and screwing through the sound
board and into fillets m n glued to the back thereof, and situated at points nearer
the centre of the sound board than the bearing points or fulcra whereby the centre
portion of the sounding board is bellied or drawn up towards the string frame
until the true bearing on the strings on the bridge is obtained, the screws g before
mentioned assisting to obtain the true bearing of the strings on the bridge beyond
the limits to which the bellying of the sound board would otherwise extend, and
to render the adjustment of the sound board uniform throughout.
Having now particularly described and ascertained the nature of the said
Invention, and in what manner the same is to be performed, I declare that what
I claim is
1st A pianoforte wherein the string frame is constructed as herein described, so
as to be self-supporting without the use of wooden bracings, and is placed, with the
sound board attached and completely strung, into the case.
2nd The method of adjusting the bellying of the sounding board by a leverage
action produced by the sounding board bearing against the string-frame at
diametrically opposite points, and by screws situated between the bearing-points
or fulcra, substantially as herein specified.

page_text: 3rd The method of adjustably supporting the sound board against the pressure
of the strings, and attaching it to the frame in such way that the edges of the
sound board are free from the frame substantially as described.
4th The method of attaching the sound board to the string frame by the
combination of the two adjustments claimed under clauses 2. and 3. and as herein
described and represented, whereby the bellying of the sound board and the
pressure of the strings upon it is capable of being regulated at all points as
described.