IMPROVEMENTS IN MACHINES FOR CUTTING OR DRESSING STONE
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by George Anderson at the Office of the
Commissioners of Patents on the 9th June 1882.
GEORGE ANDERSON, of Arbroath, in the County of Forfar, North-Britain,
"IMPROVEMENTS IN MACHINES FOR CUTTING OR DRESSING STONE,"
This Invention which relates to machines for cutting or dressing stone, has for
its object so to improve the construction or arrangement of such machines, as to
produce more regular motions of various parts, and in general to render them more
efficient in action.
The Invention is applied to stone cutting machines of the class in which a table
carrying or supporting the stone to be cut, is reciprocated or traversed back and
forth beneath or in front of revolving or stationary cutters or saws, and the
improvements consist mainly in arranging in combination with the table of such
machines a novel construction or arrangement of compound racks and toothed
wheel gearing, whereby there is imparted to the table a regular traversing or
reciprocatory motion, such as has hitherto been only imperfectly obtained by the
use of expensive screw gear.
In carrying out the Invention, the reciprocating table of such stone cutting
machines is by preference made of wood instead of cast iron as usual, the fibre of
the wood running transversely, and the table proper is secured to longitudinal
wooden beams fitted below. To the lower side of these beams or to iron plates
bolted thereto, one, two, or more toothed racks are secured by preference in short
lengths abutting on each other. These racks are made double or compound, being
cast with two sets of teeth to each, the pitch of one set of teeth being also greater
than that of the other; and when there are two or more racks, the pitches of each
set of teeth of these racks are also made slightly greater or less. In gear with
these racks are fitted driving pinions, which are rotated to traverse or reciprocate
the table of the machine, two pinions being provided for each compound rack.
These driving pinions, which are by preference fitted on the same rotating shaft,
are all of the same diameter, but the pitches of their teeth being made to
correspond to those of their respective racks, the number of teeth in each pinion
differs. In a convenient arrangement where there are two compound racks fitted
Posies 2.71

page_text: to the table, the pinions have respectively 10, 11, 12 and 13 teeth. A central or
side bearing plates running over rollers or pulleys are provided as usual to carry
the table and prevent its weight bearing on the driving shaft.
To further maintain this steadiness of motion, and also to prevent the stone
being fed into the cutters irregularly by any vibrating or shaking motion of the
gearing a brake arrangement is provided, consisting of a shaft on which a pinion
or pinions are fixed to gear into one of the sets of teeth of each rack, and fitted
with a drag or brake wheel on which a strap or other brake device is caused to
act, thereby taking up all tear and wear, and preventing the saws from biting
the stone.
The advantage of the arrangement of driving gear described, is that there is no
free space or "back lash" between the teeth, and a regular and steady traversing
motion is imparted to the table.
As a further improvement upon stone cutting machines of this class, change
wheels or pinions are employed, instead of the usual cones and belts for obtaining
variations of speed of traverse of the table and consequent cutting effect.