IMPROVEMENTS IN CUTTING AND DRESSING STONE AND IN APPARATUS THEREFOR
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by Moses Kellow at the Office of the
Commissioners of Patents on the 5th July 1882.
MOSES KELLOW, of Park Quarries, Penrhyndeudraeth, in the County of
Merionethshire, Assistant Quarry-Manager "IMPROVEMENTS IN CUTTING AND
DRESSING STONE AND IN APPARATUS THEREFOR
"
My invention relates more particularly to the treatment of stone of a laminable
nature; such, for instance, as slate. In cutting material of this description it is
the practise to impart to the operating edge of the cutting instrument either a
rectilinear or a curvilinear motion. In the former case, the motion of the tool
corresponds with that commonly employed in a planing or slotting machine where
loss of time is incurred whilst the tool makes its return stroke. In the latter case,
the motion is similar to that of a circular saw; which, although continuous in its
action, is objectionable when applied transversely to the direction of the “cleavage
or plane of least resistance to separation of the material operated in on account of
the loss of power incurred under such circumstances. When a circular saw of the
ordinary type is employed there is the further disadvantage that the metal of
which it is composed must be sufficiently pliable to permit of the teeth being set
or bent laterally with a view to producing a cut sufficiently wide to clear the body
of the saw. This entails the necessity of the metal being softer than would other-
wise be preferred for a cutting tool. My invention is designed to avoid these
disadvantages and consists in the construction and use of a rotative tool holder
carrying a series of chisel-shaped cutters mounted in its periphery. These cutters
may consist of simple square bars of steel or other hard metal formed and sharpened
to a chisel edge at their outer or protruding ends. They are arranged at an angle
oblique to the radius of the tool holder and point forwards; that is to say, in the
direction they are intended to follow. They are also slightly inclined laterally;
their outer or cutting ends projecting outwards relatively to the plane of rotation
of the tool holder. The object of this lateral obliquity is to ensure the cut having
a width sufficient to give clearance; but it is obvious that the same effect might
be produced by forming the tool in a special manner towards the outer portion of
its cutting edge. I prefer to arrange the cutters as regards their lateral set so that
they project alternately towards opposite sides of the tool holder.
In using a rotative cutting apparatus of the character described, I apply it to
the stone in such a manner that the direction of motion of the cutters, when
operating, shall as nearly as practicable coincide with the plane of cleavage of the

page_text: stone. Supposing, for example, that the stone be arranged horizontally in respect
to its plane of cleavage and that the plane of rotation of the cutting apparatus be
vertical; instead of mounting the travelling bed carrying the stone at such a level
as to feed the same slightly above or slightly below the level of the saw spindle,
I cause the bed to travel at such a height relatively thereto that the cutters only
operate during their passage through a small arc of their revolution, this arc
occurring either in, the highest or lowest portion of the vertical plane of their
motion. In each of these arcs the direction of movement of the cutters most
nearly approaches the horizontal and therefore most closely coincides with the
direction of the cleavage.
I prefer to make the rotative cutting apparatus of considerable diameter, the
better to obtain approximate coincidence between the plane of cleavage and the
line of motion of the cutters whilst in operation.
By the arrangements described I am enabled to accomplish a continuous cutting
effect by means of tools tempered to an appropriate degree of hardness and
applied approximately in the direction of the cleavage of the stone operated on;
by which means power is economised, time saved and wear of tools and machinery.
reduced.
It will be readily perceived that a rotative cutting apparatus of the character
described is applicable, not only for dividing blocks or slabs of stone of a laminable
nature, but for producing grooves in, or dressing the edges or faces of, such blocks
or slabs; it being only necessary to vary the height of the feed table accordingly
or to adjust the block or slab in position thereon relatively to the course traced by
the revolving cutters.