Improve- MENTS IN OR CONNECTED WITH TOOLS FOR CUTTING COAL, STONE, SLATE, MARBLE OR SIMILAR MATERIALS
Year: 1875

page_text: LETTERS PATENT to Bain Munro, of Forfar, in the County of
Forfar, North Britain, Engineer, for the Invention of "Improve-
MENTS IN OR CONNECTED WITH TOOLS FOR CUTTING COAL, STONE, SLATE,
MARBLE OR SIMILAR MATERIALS."
PROVISIONAL SPECIFICATION left by the said Bain Munro at the
Office of the Commissioners of Patents, with his Petition, on the
6th November 1875.
I, BAIN MUNRO, of Forfar, in the County of Forfar, North Britain,
Engineer, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN OR CONNECTED WITH TOOLS FOR CUTTING COAL, STONE,
SLATE, MARBLE, OR SIMILAR MATERIALS," to be as follows, that is to
say:
This Invention relates principally to improved modes of fixing cutters
in the cutter holders or tools of machines used for cutting stone, coal,
slate, marble, or similar materials.

page_text: In carrying out the Invention the holder is formed with a conical
recess or socket on its face, and a hole is bored through from the bottom
of the conical recess to the back of the holder.
The cutter is in the form of a hollow or solid cone or conical frus-
trum, and is formed with a nipple or button on a short shank at its
small end, which button is adapted to engage in a kind of internally-
grooved cup formed in the end of a holding spindle which is entered
through the hole in the holder.
The cup. end of the holding spindle is slit diametrically so that the
two halves can spring a little to or from each other; and when the
button of the cutter is forced in it opens the halves, and they then close
on it. The holding spindle projects beyond the back of the holder, a
nut being screwed on its outer end, and a helical spring is placed on it
between the nut and the back of the holder. The spring draws the
spindle towards the back, and thereby draws the cutter into its socket, 1
and when the parts are thus drawn in, the cup of the holding spindle
cannot open and the cutter is securely held.
When a cutter is to be put in or taken out the holding spindle is
simply pressed forward, the spring being compressed, and then the
cutter can be easily engaged or disengaged. The screw nut is formed a
with a notch in which the end of the spring engages, and the other end
of the spring being retained by a pin in the back of the holder, the
spring prevents the nut from unscrewing.
It is an advantage of the improved fixing contrivance, that cutters of

page_text: WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Sixth day of November, in the year
of our Lord One thousand eight hundred and seventy-five, in the
thirty-ninth year of Her reign, did, for Herself, Her heirs and suc-
cessors, give and grant unto me, the said Bain Munro, Her special
licence that I, the said Bain Munro, my executors, administrators,
and assigns, or such others as I, the said Bain Munro, 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 OR CONNECTED WITH TOOLS FOR CUTTING COAL, STONE, SLATE, MARBLE, OR
SIMILAR MATERIALS," upon the condition (amongst others) that I, the
said Bain Munro, 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 Bain Munro, 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 in writing, reference being had to the accom-
panying Drawings, that is to say:-
My said Invention relates principally to improved modes of fixing
cutters in the cutter holders, or tools of machines used for cutting coal,
stone, slate, marble, or similar materials.
And in carrying out my Invention the holder is formed with a conical
or conoidal recess or socket in its face, and a hole is bored through from
the bottom of the recess, to the back of the holder.
The cutter is in the form of a hollow, or solid cone, or conoidal
frustrum, and is formed or fitted with a shank adapted for being held by
the inner end of a spindle which is entered through the hole in the
holder.
'
The inner end of the holding spindle is in some modifications slit

page_text: diametrically, so that the two halves can spring a little to or from each
other, and when the shank of the cutter is forced in, it is gripped by the
two sides of the spindle. The holding spindle has a nut screwed on its
back end, and in some cases a helical spring is applied, as herein-after
explained:
And in order that my said Invention and the manner of performing
the same may be properly understood I hereunto append a Sheet of
explanatory Drawings, to be herein-after referred to, and representing
various modifications of my holding appliances for conical cutters. In
these Drawings the same reference letters are used to mark the same or
like parts wherever they are repeated.
Figure 1 is a section of a tool holder H fitted with three conical
cutters C; and Figure 2 is a corresponding front elevation.
The three cutters C, which may be of cast iron of suitable quality, are
shown alike, being each in the shape of a conoidal frustrum with a
conical cavity at the front, and formed with a nipple-shaped or button-
shaped shank N. The nipple N of the cutter O is adapted to engage in
a kind of internally-grooved cup formed in the inner end of a holding
spindle S, which is entered through the hole in the holder H.
The cup end of the holding spindle S is slit diametrically, so that the 2
two halves can spring a little to or from each other; and when the
spindle is out or partly out towards the larger end of its hole, the
nipple N of the cutter can be forced in so as to engage with the cup
end of the spindle S; and when afterwards the spindle S with the
cutter C thus engaged with it are put back into the hole in the holder H 2
the half parts of the spindle S cannot open, and the cutter is securely
locked in position.
A nut B screwed on the back end of the spindle S and bearing
against the back of the holder H, as shown at D, may be used to hold
the spindle in position, or a helical spring P may be put on the 3
spindle S between the nut B, and either the back of the holder H, as
shown at E, or in a socket formed in the back of the holder, as shown
at F. When a spring P is thus applied it is unnecessary to unscrew
the nut B when changing a cutter, as the spindle S can be forced
forward sufficiently on compressing the spring to allow of the cutter C 3
being disengaged and another substituted. The spring P has its ends

page_text: catching in notches, one in the holder H, and the other in the nut B,
and thereby prevents the nut from unscrewing.
To facilitate. the screwing up of the nut B the spindle S may be
formed with a squared part, on which a square washer G. is put, as
shown at F, so that one key may be applied to screw up the nut B.
Figure 3 is a section of a holder H constructed for two cutters C;
which are shown as made with two different forms of hook nipples N
by which they engage with counterpart hooks on the holding
spindle S.
Instead of forming each cutter C with a shank or nipple N in. the
same piece with it, the shank may be part of a separate piece or pin M
of malleable iron, as shown in Figure 4, and the remaining Figures, such
pin M, being formed with a head fitting the inner part of the conical
cavity of the cutter C, and the shank passing through a hole in the
cutter.
In the modification shown in Figure 4 the pin M is formed with a
nipple or button to engage with the holding spindle S just like what is
shown in Figure 1.
i
In Figure 5 the pin M is formed with a broad nipple, and the end of
the holding spindle S'is slotted across to the shape of the broad nipple,
the nipple being entered transversely into the slot in order to engage
one part with the other.
When the holding spindle S is split and the sides capable of opening
or closing, as herein-before described, excepting with reference to
Figure 5, I find that the wedge-like grip of the two sides of the
spindle S when the spindle is drawn back by the nut B, is quite
sufficient to hold the cutter C without any nipple or corresponding catch
being formed on its shank or on its pin M, which shank or pin may be
made cylindrical, as shown in Figures 6 and 7. The latter Figure 7
shows a single cutter C as fitted to a holder H of the kind used for
fixing in sockets in a disc to form a circular saw.
It is an advantage of my improved fixing contrivances, that cutters
of simple cast iron can be used with them; the cutters may, however,
be of any other suitable metal if preferred.
Having thus particularly described my said Invention, and the
manner of performing the same, I have to state that I do not restrict

page_text: myself to the precise details herein described or delineated, but that
what I believe to be novel and original, and claim as the In-
vention secured to me by the herein-before in part recited Letters
Patent is,―
1. The securing of the conical or conoidal cutter in its holder by
means of a spindle which passes through to the back of the holder, and
which engages with the cutter or with a pin passing through the cutter
by means of a nipple or catch, or by a simple wedge-like gripping
action, all substantially as herein-before described.
2. The combining of the spring with the other details in the modes
and for the purposes substantially as herein-before described.
In witness whereof, I, the said Bain Munro, have hereunto set
my hand and seal, this Second day of May, in the year of our
Lord One thousand eight hundred and seventy-six..