AN IMPROVED CIRCULAR SAW
Year: 1878

page_text: LETTERS PATENT to William Robert Lake, of the Firm of Haseltine, Lake,
& Co., Patent Agents, Southampton Buildings, London, for the Invention of
"AN IMPROVED CIRCULAR SAW." A communication from abroad by George
F. Simonds, of Fitchburg, Massachusetts, United States of America.
Sealed the 22nd October 1878, and dated the 3rd September 1878.
COMPLETE SPECIFICATION filed by the said William Robert Lake at the
Office of the Commissioners of Patents on the 3rd September 1878.
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, Co., Patent Agents,
Southampton Buildings, London. "AN IMPROVED CIRCULAR SAW." [A communica-
tion from abroad by George F. Simonds, of Fitchburg, Massachusetts, United States
of America.]
This Invention relates to an improved circular saw which will work at a higher
speed and wear longer than such saws as ordinarily constructed.
The said Invention is illustrated in the accompanying Drawing, in which,―
Figure 1 represents a finished saw.
Figure 2 represents a saw in position for testing, as herein-after described, with
a straight edge applied across its surface.
Figure 3 shows a section through the line x, x, Figure 1, of a saw when made
"firm" throughout, as herein-after described.
Figure 4 shows a section of a saw with a straight edge applied from the eye to the
circumference, and indicates the condition termed "loose," as herein-after described.
Figure 5 shows the same condition from the eye to the circumference, but with
the oye deflected from the plane of the circumference.
Figure 6 shows a section of my improved saw with a straight edge applied across
its surface.
To enable others to make and use the said Invention I will now proceed to
describe the exact manner in which the same has been carried into practice.
In the manufacture of circular saws it is necessary that account should be taken
of and due allowance made for the effect of the speed or rate of revolution at which
[Price 6d

page_text: the saw is designed to run, and it has been found necessary to give to such saws
when finished certain delicate and important conditions, having reference, it is
supposed, to the tension or strain of different parts upon each other, in order to
enable them to perform their work well. These conditions have been secured by the
manner in which a saw is hammered, and they are indicated by certain appearances
which are presented when a saw is tested in the following manner, that is to say :-
When a circular saw is prepared for use it is held up vertically, as shewn in
Figure 1, and with its circumference resting on a support. Its surface, if it is of
uniform thickness, should present substantially a plane, but when a saw is laid
down horizontally, or nearly so, as shewn in Figure 2, and supported at opposito
parts of the circumference, it will spring or sag either by its own weight or by the
application of moderate force, so as to distort its surface. This distortion could be
detected and observed by placing a straight edge across the surface of the saw, and
its character depended upon the manner in which the saw had been hammered. To
bring the saw into proper condition to perform the work required of it, the work-
man has been accustomed to hold the saw in the manner indicated by Figure 2,
and to apply a straight edge to its surface from the eye to the circumference at right
angles to a line extending between the two points of support. If the saw springs,
so that a line of light appears between its surface and the straight edge, the saw is
said to be "loose;" if no such line of light appears the saw is said to be "firm."
These terms are supposed to indicate different conditions of saws as to the tension or
strain between different parts.
Figure 4 shows a section of a saw with a straight edge applied to it from the eye
to the circumference. The space between the curved line or surface of the saw and
the straight line of the straight edge represents in exaggerated degree the line of
light which the workman observes.
The saw is turned and supported on different points, and the straight edge applied
repeatedly, so that the "looseness" shall be the same around the entire zone.
Sometimes the saw is so hammered that the eye will fall away from a straight
edge applied across the whole disc, as shewn in Figure 5, but still not so, but that
when applied from the eye to the circumference the saw will be "loose between
those two points, and present the appearance indicated by Figure 4.
"
"
The condition indicated by the term "loose," and by virtue of which the surface
falls away from a straight edge when applied to it in the manner described, is
essential to all saws moving at high speed, and the amount of "looseness
must
vary with the size of saws, the rate of revolution, and to some extent with their
thickness; but it will be observed that the condition into which saws have been
put or left in finishing is such that under the test applied they are
"Iooso in a
zone between the eye and the circumferenco, and the surface of the saw under the
straight edge presents a curved line.
"
In my improved saw the condition into which it is put or left in finishing is
widely different as to its "looseness." The straight edge is applied entirely from
one side to the other, in the manner represented in Figure 6, and the saw must fall
away from it in such a manner that the eye will be the part at the greatest distance
from it, and the line of the surface of the saw below it instead of being curved
must be straight, so that if the straight edge were applied, as in Figure 4, to a
radius, or from the eye to the circumference, the saw would be "firm between
those two points, and "loose" from one point in the circumference to the opposite
point, and the lines of deflection are straight lines instead of curved. Thus the
space between the surface of the saw and the straight edge is bounded, as seen in
Figure 6, entirely by straight lines which form a triangle.
"
It will be rendily seen that the condition of such a saw as to the tension or strain
of its parts is very different from that which must exist in a saw which has a
"loose" zone between the eye and the circumference, and that the strain of the
centrifugal force must be exerted and distributed very differently.
The advantage which the said improved saw possesses over saws as heretofore

page_text: mado, is that the former will stand greater pressure, work faster, and last longer
than the latter.
Having thus fully described the said Invention as communicated to me by my
foreign correspondent, and the manuer of performing the same, I wish it understood
I claim, the improved circular saw mado "firm with roforence to its radii, but
"loose" with reference to its diameter, as above described.
"
In witness whereof, I, the said William Robert Lake, have hereunto set
my hand and scal, this Third day of September, in the year of our
Lord One thousand eight hundred and seventy-eight.
W. ROB. LAKE. (LS)