A DOVETAILING MACHINE
Year: 1868

page_text: LETTERS PATENT to William Tighe Hamilton, of Rathmines, Dublin,
for the Invention of "A DOVETAILING MACHINE."
Sealed the 15th January 1869, and dated the 22nd July 1868.
PROVISIONAL SPECIFICATION left by the said William Tighe Hamilton
at the Office of the Commissioners of Patents, with his Petition,
on the 22nd July 1868.
I, WILLIAM TIGHE HAMILTON, of Rathmines, Dublin, do hereby
declare the nature of the said Invention for "A DOVETAILING MACHINE," to
be as follows:-
A disk carrying a circular saw is mounted on an axle free to reciprocate
as it rotates. The mounting is in the nature of a universal joint, the
inner member working on a pivot through the axle, the outer in like
manner on a pivot through the inner. The pivots being at right angles
the saw is free to move in all directions. The disk revolves against a
ring attached to it by a plate which carries an arm above and an arm
below the saw, with slots in which pins work, carried by a surmounting
frame. The plane of the saw is thus always in a vertical position, and

page_text: when the axle is made to reciprocate as it rotates the saw will always
intersect itself in a vertical line under the pins & slots; its operation
will thus be in the form of a triangle. The wood being passed up the
front of the saw vertically a tail will be cut. When the frame is elevated
and the wood moved on horizontally a pin will be out, The sweep of
the saw will cut them so as to fit each other. A small vertical movement
corrects the circular cutting of the saw.
It will do
It is thus
An important variety of this Invention is the substitution of what is
called the drunken saw for the saw on the jointed mounting. The saw
is then at a fixed instead of a variable angle of inclination,
the same work but of a size proportioned to its own size.
not so manageable for fine work, but the principle is the
reciprocation of the axle may be produced in various ways. I prefer as
most suited the principle of parallel motion, which I have specified for
a separate Patent, as also applicable to other machines,
same. The
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said William Tighe Hamilton in the Great Seal Patent
Office on the 20th January 1869.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
TIGHE HAMILTON, of Rathmines, Dublin, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-second day of July, in the 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 Tighe Hamilton, Her special
licence that I, the said William Tighe Hamilton, my executors, adminis-
trators, and assigns, or such others as I, the said William Tighe
Hamilton, 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
"A DOVETAILING MACHINE," upon the condition (amongst others) that I,
the said William Tighe Hamilton, my executors or administrators, by an
instrument in writing under my, or their, or one of their hands and seals,

page_text: should particularly describe and ascertain the nature of the said Inven-
tion, 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 Tighe Hamilton, 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 :-
The principle of this machine is this, a disc carrying a circular saw
is mounted upon an axle capable of reciprocating as it rotates in its
bearings. The movement of this disc is so governed that the saw shall
always be in a vertical plane, and by its sweep eat away the material
offered to it in a triangular form. The mounting of the disc is upon
the principle of a universal joint, the inner member of which is free to
turn upon a pin passing through the axle, whilst the disc or outer
member is free to turn upon a like pin passing through the inner member..
These pins are at right angles to each other but in the same plane. The
disc and with it the saw is thus free to move in every direction, but a
rim or strap working on the circumference or side of the diso maintains
them always in a vertical plane, either by turning upon two pivots
provided in the frame, one above and the other below the saw, or by
working in a horizontal slot at the back of the saw. In the former case,
when the axle revolves and reciprocates, the varying planes of the saw
will continually intersect in a vertical line passing through the upper
and lower pivots; in the latter case the vertical line will also pass
through the axle. In both cases the entire cutting operation of the saw
will be confined within the limits of the triangle so formed. When the
material is passed up the front of the saw vertically a tail will be cut.
When the material is advanced endwise or horizontally upon the saw
the interval between two pins will be cut, the circular effect of the saw
being rectified by a small vertical movement of the feeding table. The
reciprocation of the axle may be effected in any of the usual methods,
but the most suitable is that patented concurrently with this, entitled
"An Improved Method of Converting Circular into Reciprocating Motion."
This presents the great advantage that by mounting the saw disk upon
the axle, and also a reciprocator connected with it by a link so that
they shall work parallel, the mere rotation of the axle will cause the

page_text: saw to cut a tail proportioned the radius of the saw, whilst by mounting
in the axle a second reciprocator inclined in the contrary direction to
the other the size of the tail can be diminished or increased to any
desired size without altering the angle of the saw cut.
Another modification of the same principle is to mount upon the
same axle a reciprocator, and also what is commonly called a drunken
saw, that is, a saw mounted at a fixed inclination and without using a
universal joint. The saw will thus be reversed at every half turn, and
cut tails or pins of a breadth proportioned to its size and inclination;
but as the breadth cannot be less than the fixed sweep of the saw it is
not so useful a form of the Invention as the first specified.
In witness whereof, I, the said William Tighe Hamilton, have
hereunto set my hand and seal, this Nineteenth day of January,
in the year of our Lord One thousand eight hundred and sixty-
nine.
W. TIGHE HAMILTON. (L.S.)