IMPROVEMENTS IN MORTICE MACHINE CHISELS
Year: 1871

page_text: LETTERS PATENT to Bernard Clarke, of Aston, near Birmingham, in
the County of Warwick, Manager of Joinery Works, for the
Invention of "IMPROVEMENTS IN MORTICE MACHINE CHISELS.”
PROVISIONAL SPECIFICATION left by the said Bernard Clarke at the
Office of the Commissioners of Patents, with his Petition, on the
23rd January 1871.
I, BERNARD CLARKE, of Aston, near Birmingham, in the County of
Warwick, Manager of Joinery Works, do hereby declare the nature of
the said Invention for "IMPROVEMENTS IN MORTICE MACHINE CHISELS," to be
as follows:-
:―
"
The ordinary mortice machine chisel consists of a single cutting tool
fixed in the machine and carried forward with the required reciprocating
motion through a certain distance and then reversed or turned on its
axis, when its continued action completes the mortice. In cutting a
second or parallel mortice the chisel is made to move laterally the
required distance, and has then the required reciprocating motion given
to it to cut the second or parallel mortice.

page_text: In constructing mortice machine chisels according to my Invention
I make the chisel of a fork form, the ends of the branches of the fork
being formed into chisel edges. This chisel is fixed in the machine and
worked in the usual manner, excepting that in cutting parallel mortices
the lateral adjustment of the chisel herein-before described is not
required.
The turning of my improved chisel on its axis brings that branchi
which commenced the cutting of the outside mortice into the inside
mortice, and that branch which commenced the cutting of the inside
mortice is brought into the outside mortice. In this way the two
mortices are cut simultaneously, and their parallelism preserved with an
accuracy unattainable by chisels of the ordinary construction.
In making the said forked or compound chisel I either make it out
of one piece of steel, or I make the two branches of separate pieces of
steel and connect them together by screw bolts and nuts, with packing
pieces of the required thickness between them. The shank or stem by
which the chisel is fixed in the mortice machine is situated midway over
the two branches, and where the said branches are separate may be
attached to the packing piece.
Where more than two parallel mortices are required to be cut the
chisel may have the required number of branches instead of the two
described.
Chisels constructed according to my Invention may also be used for
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Bernard Clarke in the Great Seal Patent Office on
the 15th July 1871.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, BERNARD
CLARKE, of Aston, near Birmingham, in the County of Warwick,
Manager of Joinery Works, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-third day of January, in the year
of our Lord One thousand eight hundred and seventy-one, in the thirty-
fourth year of Her reign, did, for Herself, Her heirs and successors, give

page_text: and grant unto me, the said Bernard Clarke, Her special licence that I,
the said Bernard Clarke, my executors, administrators, and assigns, or
such others as I, the said Bernard Clarke, 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 MORTICE MACHINE CHISELS,"
upon the condition (amongst others) that I, the said Bernard Clarke,
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 Bernard Clarke, 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 ordinary mortice machine chisel consists of a single cutting tool
fixed in the machine and carried forward with the required reciprocating
motion through a certain distance and then reversed or turned on its
axis, when its continued action completes the mortice. In cutting a
second or parallel mortice the chisel is made to move laterally the
required distance, and has then the required reciprocating motion given
to it to cut the second or parallel mortice.
In constructing mortice machine chisels according to my Invention I
make the chisel of a fork form the ends of the branches of the fork being
formed into chisel edges. This chisel is fixed in the machine and worked
in the usual manner, excepting that in cutting parallel mortices the
lateral adjustment of the chisel herein-before described is not required.
The turning of my improved chisel on its axis brings that branch
which commenced the cutting of the outside mortice into the inside
mortice, and that branch which commenced the cutting of the inside
mortice is brought into the outside mortice. In this way the two
mortices are cut simultaneously and their parallelism preserved with
an accuracy unattainable by the use of chisels of the ordinary con-
struction:

page_text: In making the said forked or compound chisel I either make it out of
one piece of steel or I make the two branches of separate pieces of steel
and connect them together by screw bolts and nuts with packing pieces
of the required thickness between them. The shank or stem by which
the chisel is fixed in the mortice machine is situated midway over the
two branches, and where the said branches are separate may be attached
to the packing piece.
'
Where more than two parallel mortices are required to be cut the
chisel may have the required number of branches instead of the two
described.
Chisels constructed according to my Invention may also be used for
cutting single mortices.
Figure 1 of the accompanying Drawing represents in front elevation,
and Figure 2 in side elevation a small forked or compound mortice
machine chisel made of one piece of steel according to my Invention.
a is the body of the chisel having two branches or forks b, b, the
ends 62, 62, of the said branches having chisel edges; c is the shank
or stem of the compound chisel by which it is fixed in the mortice
machine.
Figure 3 represents in front elevation; Figure 4 in back elevation, and
Figure 5 in side elevation a larger mortice machine chisel made according
to my Invention, the parts being marked with the same letters of
reference as corresponding parts in Figures 1 and 2.
In the branches b, b, of the large chisel, Figures 3, 4, and 5, troughs or
grooves d, d, are made, into which the cut away wood passes during the
use of the chisel, as is well understood.
Where the branches of the forked or compound chisel are made
separately from the body of the chisel they are connected to the said body
as herein-before described, but I prefer to make the said chisel from one
piece of steel as illustrated in the accompanying Drawing.
Having explained the nature of my Invention, and the manner in
which the same is to be performed, I wish it to be understood that
I do not limit myself to the precise details herein described and
illustrated, as the same may be varied without departing from the
nature of my Invention; but I claim as my Invention the improvements
in mortice machine chisels herein-before described and illustrated in the
accompanying Drawing, that is to say, making the said chisels of a fork

page_text: form the ends of the two or more branches of the forked or compound
chisel being made into chisel edges, substantially as and for the purpose
described and illustrated.
In witness whereof, I, the said Bernard Clarke, have hereunto
set my hand and seal, this Fourteenth day of July, in the year of
our Lord One thousand eight hundred and seventy-one.
Witness,
RICHARD SKERRETT,
Clerk to George Shaw,
Birmingham.
BERNARD CLARKE. (L.S.)