IMPROVEMENTS IN BOW SAWS
Year: 1872

page_text: LETTERS PATENT to William Cotter, of Gloucester Street, Bloomsbury,
"
in the County of Middlesex, for the Invention of "IMPROVEMENTS
IN BOW SAWS."
Scaled the 10th September 1872, and dated the 11th June 1872.
PROVISIONAL SPECIFICATION left by the said William Cotter at the
Office of the Commissioners of Patents, with his Petition, on the
11th June 1872.
I, WILLIAM CUTTER, of Gloucester Street, Bloomsbury, in the County
of Middlesex, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN Bow SAWS," to be as follows :—
This Invention relates to certain improvements in the construction of
bow saws, whereby the saw is easily adjusted or removed, the operation
of cutting being also facilitated, more especially in regard to curves or
fret work, and more than double the depth of cut being effected than
can be made with the ordinary bow saw, in which the stretcher is made
with a rigid bar, the saw itself preserving the requisite adjustment of
the parts, and it being difficult to insert the saws.

page_text: By my Invention I dispense altogether with the rigid bar stretcher
by the introduction of a rising stretcher (by preference circular), through
or over which is attached a tension bar adjustable by thumbscrews on
either end, the adjustability of the saw on the handles preventing the
possibility of its falling out. The saw is applied to the handles by
adjusting fastenings, and its tension regulated by improvements applied
to such handles. The handles of the saw each extend to a rod or
stem which is provided with a slot or channel cut completely through
the axial radius, and between the extremity of the rod and the handle
a transverse channel or groove is cut, in which a pin securing the saw
is caused to gear, and which is then held firmly in position by a move-
able or sliding tube inserted on the fixed rod or stem of the handle, the
tube being also slotted in such manner as to receive the pin of the
saw tube when turned round to correspond with the slot of the saw; the
transverse slot thus fixes the pin. On the handles and close to the
frame I apply a ferrule or ring with a male screw cut thereon, and I
then pass a female screw ferrule thereon; thus by the finger and thumb
the external ferrule may be turned in either direction, and the tension
of the saw regulated. Set screws are inserted at the lower side of each
frame in order to fix the axis of the saws before working. The saw cannot
be broken by the upper screw tension, because the upper part of the
stretcher and frame come in contact.
Curves can be very readily cut by the improved saw, since the tension
need not be so great as in the rigid stretcher frame. The spring of the
stretcher renders the adjustment and fixing of the saw a matter of no
difficulty in comparison with the ordinary bow saw. Moreover, in
sawing with a great or full tension the saw is also liable to break by a
sudden jar where the stretcher will not give, but by my Invention there
is always a tendency of the saw to right itself, the elasticity of the
frame preventing fracture.

page_text: WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eleventh day of June, in the year of our
Lord One thousand eight hundred and seventy-two, in the thirty-fifth
year of Her reign, did, for Herself, Her heirs and successors, give and
grant unto me, the said William Cotter, Her special licence that I, the
said William Cotter, my exccutors, administrators, and assigns, or such
others as I, the said William Cotter, my executors, administrators, and
assigns, should at any time agree with, and no others, from time to
time and at all times thereafter during the term therein expressed,
should and lawfully might make, use, exercise, and vend, within the
United Kingdom of Great Britain and Ireland, the Channel Islands,
and Isle of Man, an Invention for."IMPROVEMENTS IN Bow Saws," upon
the condition (amongst others) that I, the said William Cotter, my
exccutors or administrators, by an instrument in writing under my, or
their, or one of their hands and seals, should particularly describe and
ascertain the nature of the said Invention, and in what manner the
same was to be performed, and cause the same to be filed in the Great
Seal Patent Office within six calendar months next and immediately
after the date of the said Letters Patent.
"
NOW KNOW YE, that I, the said William Cotter, do hereby declare
the nature of my said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the
following statement, reference being had to the Drawing hereunto
annexed, and to the figures and letters marked thereon, that is to
say :-
This Invention relates to certain improvements in the construction of
bow saw frames, whereby the saw blade is more easily adjusted to or
removed from the frame, and the operation of cutting is also greatly
facilitated, more especially for sharp curves and fret work; more than
double the depth of cut may also be obtained than with the ordinary
bow saw, in which the stretcher of the frame is straight and rigid. The
saw blade itself has in the old arrangement to preserve the requisite
adjustment of the parts of the frame, thereby presenting at all times a
difficulty in inserting the saw blades.
By my improvements I dispense altogether with the rigid bar
stretcher, and in place thereof I employ a curved stretcher (by pre-
ference of a semicircular form) rising from the fulcrums, and through

page_text: or over the stretcher is attached a tension bar or bars, adjustable by
thumb pieces on either side of the frame for regulating the tension of
the saw blade.
I also employ an improved spindle adjustment for locking the saw
blade in position, by which it is prevented from falling out, such falling
out being a source of annoyance and loss of time in manipulating with
the old bow saw. The handles are also constructed so as to regulate the
tension of the saw, and I employ set screws for fixing the spindles, so
that the saw blade is prevented from turning while in use.
The large amount of play of the side bars of the frame obtained by 1
the application of my improvements, in conjunction with the screw
ferrule arrangement, also allows of saw blades of different lengths being
used, which could not be done with the old bow saw frame; and the
flexibility of the frame prevents the breakage of the saw blade from a
sudden jerk; and the contact of the side bars with the lower parts of the
spring stretcher prevents the breakage of the side bars.
To make my Invention better understood I will proceed to describe
the same by reference to the accompanying Drawing, in which Figure 1
represents an elevation (partly in section) of my improved bow saw;
and Figures 2, 3, and 4, details on a larger scale of the spindle-locking
arrangement; Figure 5, detached view shewing the moveable bearing
sometimes employed for the spindle of the saw blade.
In Figure 1, a, a, are the side bars or armatures of the frame, and 6 is
the improved stretcher, made by preference of bent wood, so as to form a
spring, but which may be made of steel or other suitable metal. The 2
ends of this stretcher are knuckle jointed at c, c, to the side bars a, a,
and the upper ends of these bars are connected to the spring stretcher b
by the tension rods d, d, furnished at their outer ends with thumb
pieces e, e, their inner ends being screw threaded and passing, as shewn
by the dotted lines, into holes in the stretcher b and through female
screws cut in the metal pieces f. f, which pass through the whole
thickness of the stretcher. By this arrangement, if the thumb pieces be
turned, the side bars a, a, will be moved on the joints c, c, and the lower
ends of the bars will thereby be moved towards or from one another
(according to the direction in which the tension rods are turned), and
thus regulate the tension of the saw blade. The handles g, g, are each
furnished with a spindle h and sliding tube h¹, passing through holes in

page_text: the lower ends of the side bars a, a, of the frame, as shewn by the
sectional part of Figure 1; the inner ends of these spindles receive the
ends of the saw blade, as herein-after described. On each handle
outside the frame I fix a ferrule i cut with a male screw, and on this
ferrule I pass another ferrule j having a female screw cut therein, a
washer k being placed between the ends of the ferrules j and the side
bars a, a.
This screw-ferrule arrangement allows of regulating the
tension of the saw blade, as by merely turning the outer ferrules j by
the hands the spindles h, h, holding the ends of the saw blade will be
moved outwards or inwards according to the direction in which the
ferrules j,j, are turned; 1, 1, are set screws fixing the spindles h, and
thereby preventing the saw blade turning when being used; those set
screws pass through female screws cut in the metal rods m, m, which fit
in holes passing through the side bars a, a.
I will now describe the spindle locking arrangement for holding the
ends of the saw blade. Figure 2 shews a plan of part of one of the
spindles and its tube and of the saw blade q, the spindle and tube being
shewn in the position to receive the end of the saw blade; Figure 3, side
elevation of same, and, also end elevation of spindle; Figure 4, side
elevation, shewing the end of the saw blade applied to the spindle and
locked by the tube.
The spindle has a longitudinal slot n cut completely through it,
the width of the slot being somewhat greater than the thickness of the
saw blade. The spindle has also a transverse slot o cut in it to receive
the pin p of the saw blade. On the spindle is placed so as to slide freely
thereon a tube h', also cut with a longitudinal and a transverse slot, as
seen in plan, Figure 2. By this arrangement to fix the end of the saw
blade on the spindle, the end of the saw blade must be passed into the
longitudinal slot n of the spindle and the pin p in the transverse slot o;
the tube h¹ must then be turned a quarter of a revolution, so as to bring
its longitudinal slot in a line with the pin p, and then moved forward
until the pin is brought into the transverse slot of the tube h', which
latter is finally turned another quarter of a revolution, so as to occupy
the position shewn in Figure 4, and the end of the saw blade will be
firmly locked. To remove the end of the saw blade the tube h¹ must be
moved in the opposite direction to that described for locking it. The
pin p may be fixed in the saw blade, and can be headed at both ends as
it does not require to be removed.

page_text: Fifthly. The employment of a revolving bearing for the spindle, as
herein-before described and shewn in Figure 5 of the accompanying
Drawing.
Sixthly. The employment of two tension rods, as herein-before
described and represented in the accompanying Drawing.
In witness whercof, I, the said William Cotter, have hereto set
my hand and scal, this Tenth day of December, in the year of
our Lord One thousand cight hundred and seventy-two.
▸ Witness,
W. A. GILBEE.
W. COTTER. (L.S.)