IMPROVEMENTS IN MACHINERY AND APPARATUS FOR DRESSING AND FURROWING MILLSTONES
Year: 1871

page_text: PROVISIONAL SPECIFICATION left by Thomas Sturgeon at the Office
of the Commissioners of Patents, with his Petition, on the 19th
August 1871.
I, THOMAS STURGEON, of 7, Corn Exchange, Leeds, Engineer, do
hereby declare the nature of the said Invention for "IMPROVEMENTS IN
MACHINERY AND APPARATUS FOR DRESSING AND FURROWING MILLSTONES," to be
as follows:-
One part of my Invention consists in employing a metal staff or
prover truly planed, which lies across and rests upon the stone requiring
to be dressed. I fix to this staff or prover a metal guide upon which a
slide is fixed carrying a frame in which one or more chisel holders are
fixed, and I give an upward movement to the chisels or holders by
suitable mechanism which are allowed to fall by their own weight.
Adjusting stops are arranged so as to regulate the blow of the chisels
and the depth of the cut on the stones. The frame carrying the chisel
holders and chisels has a backward and forward motion imparted to it
by hand, and is so arranged that the hard or high parts of the stone
can be dressed by the operator more or less as occasion may require.

page_text: A traversing motion is given to the frame in which the chisel holder or
holders and chisels are fixed by means of a screw, which is moved by a
wheel fixed at one end of the screw and which comes in contact with
a pawl or pawls, and thus gives motion to the screw each time the frame
carrying the chisel holders and chisels makes a backward or forward t
movement when dressing the stone, and by reversing the pawls the
screw or traverse can be reversed as required. The wheels fixed on
the screw can be readily changed in order that the dressing of the
stones may be varied and rendered coarse or fine as required.
One or
more chisels may be arranged in the frame so as to give any length 1
of dress required, without having to traverse the moveable slide, except
for the purpose of moving the screw, or a series of chisels may be
arranged side by side so as to produce a number of cuts at the same
time, by which means the work can be done much more rapidly.
Another part of my Invention consists in arranging the chisels so as :
to leave equal spaces between the chisels uncut, and then after being
traversed laterally by the feed screw so as to make the required number
of cuts across one or more lands they are moved longitudinally by means
of another screw or by hand and traversed back again so as to cut the
úncut spaces. In place of using a metal staff or prover for carrying the
moveable slide, a semicircular frame resting on the stone may be used to
carry the frame in which the chisel holders work, having a bearing in the
eye or centre of the stone and being furnished with suitable screws to
adjust it accurately to the centre. Or the staff itself may be furnished
with an adjustable central bearing, and firmly fixed to the centre of the
stone by means of adjusting screws. In cases where a machine is worked
with a central bearing, and where it is desired to dress the stone in the
form of an incline or cone towards the eye or centre of the stone, I so
arrange the slide bar upon which the frame of the chisel holder slides
that it can be adjusted to and fixed at any desired inclination so as to
give an inclined form or cone dress from the edge of the stone towards
the eye, and in these cases instead of the traversing screw before-
described, I prefer to use a motion for giving the necessary traverse
consisting of a worm working in a worm wheel or segment, the worm
wheel or segment being placed concentric with the stone so that the
dressing will not be produced in parallel straight lines, but in a series
of radial lines necessary for dressing conical surfaces. In case the
frame in which the chisel holder or holders is fixed requires sup-

page_text: porting at its extremity, a supporting foot or frame may be used for
the purpose, or a roller may be fixed to the frame to reduce the
friction.
For the purpose of dressing the furrows of millstones I provide the
machine with a stop or guide of a form corresponding to the form it is
desired to give to the furrows. This stop or guide is fixed to the move-
able slide, and regulates the fall of the chisel holder and consequently
the cut, thereby giving to the furrow the shape of the guide or stop.
In place of employing a metal staff or prover as before described.
for the purpose of carrying the slide and frame in which the chisel
holders. are placed, I form a frame consisting of two metal bars truly
planed to rest on the stone and connected together so as to support
both ends of the moveable slide which carries the frame in which the
chisel holders are fixed, so that by this means the frame carrying the
chisel holders can have a traverse sufficiently great to dress a number
of lands or what is called a whole quarter at a time. Friction rollers
may be fixed at each end of the moveable slide running in truly planed
grooves on the frame, or the moveable slide may be provided with truly
planed grooves or guides to slide upon without rollers..
In the plans described above for dressing millstones with chisels fixed
in chisel holders, to which an upward and downward motion is imparted
by raising them by any convenient mechanism and allowing them to
drop by their own weight, the mechanism for raising the chisels may
be dispensed with by using springs to lift the chisels or chisel holders,
and the downward or cutting stroke being imparted to them by means
of the hand acting on a suitable handle connected to the chisels or
chisel holders for forcing down the same.
The frames carrying the moveable slide may be fixed to the stone