IMPROVEMENTS IN THE CONSTRUCTION OF CIRCULAR SAWS OR CUTTERS MORE ESPECIALLY APPLICABLE FOR CUTTING SLATE AND STONE
Year: 1868

page_text: LETTERS PATENT to William Thomas, of Number 5, Ellinor Street,
in the Town and County of Carnarvon, Engineer, for the Invention
of "IMPROVEMENTS IN THE CONSTRUCTION OF CIRCULAR SAWS OR CUTTERS
MORE ESPECIALLY APPLICABLE FOR CUTTING SLATE AND STONE."
Sealed the 16th March 1869, and dated the 23rd September 1868.
PROVISIONAL SPECIFICATION left by the said William Thomas at
the Office of the Commissioners of Patents, with his Petition, on
the 23rd September 1868.
I, WILLIAM THOMAS, of Number 5, Ellinor Street, in the Town and
County of Carnarvon, Engineer, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN THE CONSTRUCTION OF CIRCULAR SAWS
OR CUTTERS, MORE ESPECIALLY APPLICABLE FOR CUTTING SLATE AND STONE," to be
as follows:-
The object of this Invention is to reduce the cost and facilitate the

page_text: operation of cutting and shaping slate, rock, or other similar hard
material, hitherto chiefly effected by means of circular saws the teeth of
which have been cut out of a single circular plate of steel of which the
saw was made.
In constructing circular saws according to my Invention I form the
saws of a number of triangularly-shaped segments, each segment forming
a separate and independent tooth. These teeth or segments are
retained or held between two circular discs or plates, in one of which a
number of pins or dowels is securely fixed, two or more to each tooth;
the pins projecting through the several teeth enter holes formed in the
second disc. The two plates with the segments between them and
forming a saw are placed upon an ordinary saw spindle and screwed up
firmly between washers. The advantages arising from thus constructing
a circular saw are that as the segments or teeth are entirely independent
of one another, any tooth may be taken out separately and replaced by
another (should the first be injured), or it may be ground and sharpened
on an ordinary grindstone and replaced, or the whole of the teeth
may be taken out, ground, and replaced in a short time and at a
trifling cost for labour, entirely obviating the necessity for the use
of files at present required for sharpening the teeth of ordinary saws,
thus saving a very heavy item of expense at present necessary.
These teeth may be set like those of an ordinary saw, or may be
made thicker at the point to gain a clearance with little or no extra
cost.
.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said William Thomas in the Great Seal Patent Office
on the 16th March 1869.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
THOMAS, of No. 5, Ellinor Street, in the Town and County of Car-
narvon, Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-third day of September, in the

page_text: year of our Lord One thousand eight hundred and sixty-eight, in the
thirty-second year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said William Thomas, Her special licence,
that I, the said William Thomas, my executors, administrators, and assigns,
or such others as I, the said William Thomas, my executors, adminis-
trators, 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
THE CONSTRUCTION OF CIRCULAR SAWS OR CUTTERS, MORE ESPECIALLY APPLICABLE
FOR CUTTING SLATE AND STONE," upon the condition (amongst others) that
I, the said William Thomas, my executors 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 Thomas, do hereby
declare the nature of the said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and
by the following statement thereof, that is to say:-
The object of this Invention is to reduce the cost and facilitate the
operation of cutting and shaping slate, rock, or other similar hard
material, hitherto chiefly effected by means of circular saws, the teeth
of which have been cut out of a single circular plate of steel of which
the saw was made.
In constructing circular saws according to my Invention, I form
the saws of a number of triangularly or other suitably shaped segments,
each segment forming a separate and independent tooth. These teeth
or segments are retained or held between two circular discs or plates in
one of which a number of pins or dowels are securely fixed two or more
to each tooth; the pins projecting through the several teeth enter holes
formed in the second disc. The two plates with the segments between

page_text: them, forming a saw, are placed upon an ordinary saw spindle and
screwed up firmly between washers.
Having thus described the nature of my Invention I proceed to
describe the way of performing the same.
Figure 1 shows a section, and Figure 2 a plan of a saw constructed
according to my Invention. A, A, are the teeth; B, B, are the pins
attached to and projecting from the annular plate; C, C¹, is the other
annular plate; E is the saw shaft carrying on it a washer or collar F
which is prevented turning around the shaft by the key D and which
is prevented moving endwise by the shoulder E' formed upon the shaft;
G is a moveable collar which screws on to a thread cut in the shaft.
The plate C is put on to the shaft and brought up against the fixed
collar F, and is prevented from turning around the shaft by the key D.
The separate teeth A, A, are then placed upon it, the pins B, B, on the
plate C fitting into the corresponding holes in the teeth A, A, the
other plate C¹ is then put on the shaft, and the pins B, B, which
project through the teeth fit into corresponding holes in the annular
plate C¹. The moveable collar G is then put on and screwed up tight,
the whole saw being thus held fast. The inner portions of the teeth
A, A, are, as shown in Figure 2, cut of such size that they fit closely to
one another, thus forming a continuous disc of which the inner or
central portions of the teeth are segments. The peculiar advantage of
this is that when in the cutting process a strain is put upon the
extremity of a particular tooth the strain is not entirely borne by the
pins carrying the teeth, but is distributed through the adjacent teeth.
This method of arranging the teeth also prevents them wearing loose
on their pins.
The advantages arising from constructing a circular saw as above
described are that as the segments or teeth are entirely independent of
one another any tooth may be taken out separately and replaced by
another (should the first be injured), or it may be ground and sharpened
on an ordinary grindstone and replaced, or the whole of the teeth may
be taken out, ground, and replaced in a short time and at a trifling cost
for labour, entirely obviating the necessity for the use of files at present
required for sharpening the teeth of ordinary saws, thus saving a very
heavy item of expense at present necessary. These teeth may be set

page_text: like those of an ordinary saw or may be made thicker at the point to
gain a clearance with little or no extra cost.
In witness whereof, I, the said William Thomas, have hereunto
set my hand and seal, this 13th day of March, in the year of
our Lord One thousand eight hundred and sixty-nine.
Witness to the signature of
William Thomas,
T. G. ROBERTS.
WILLIAM THOMAS. (L.S.)