IMPROVEMENTS IN MACHINERY AND APPARATUS FOR DRESSING AND FURROWING MILLSTONES, AND FOR DRESSING OTHER STONES
Year: 1872

page_text: PROVISIONAL SPECIFICATION left by Thomas Sturgeon at the Office
of the Commissioners of Patents, with his Petition, on the 16th
February 1872.
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, AND FOR
DRESSING OTHER STONES," to be as follows:-
One part of my Invention consists in using a metal staff or power
truly planed, which lies across and rests upon the stone requiring to
be dressed. I mount upon the staff or power a sliding saddle upon
which a transverse slide works carrying an arm or guide in which one
or more chisel holders slide up and down, and I give an upward motion
to the chisels and holders by a crank, cam, or other suitable motion,
and allow them 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 stone. The saddle carrying the transve slide has
a backward and forward motion imparted to it by hand. A traversing
motion is given to the transverse slide by means of a screw which

page_text: to the screw each time the saddle makes a backward or forward motion
when dressing the stone, and by reversing the pawls the traverse can be
reversed as required.
The wheels fixed on the end of the screw, and which are moved
by the pawl or pawls before referred to, can be readily changed in order
that the dressing of the stones may be varied and rendered coarse or fine
as needed.
For the purpose of dressing the stone to a particular form such as an
ornamental moulding or the furrows and lands 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 moulding or furrows. This stop or guide
is fixed to the saddle and regulates the fall of the chisel holder, and
consequently the cut, thereby giving to the stone or furrow the shape.
of the guide or stop.
By one part of my Invention the necessary motion may be imparted
to the crank, cam, or other mechanizm by means of toothed wheels
worked by a pinion on the saddle, which by gearing into a rack formed
on to the bed or staff of the machine gives a revolving motion to
the crank whenever the saddle is moved to or fro upon the staff. Or
instead of the to-and-fro motion of the saddle being made to impart the
necessary revolving motion to the crank as just described, the revolving
motion may be imparted direct to the crank by hand by means of a
handle, and the crank shaft may be so geared to the pinion or wheel
which works in the rack as to give the necessary to-and-fro motion to
the saddle when the handle is turned.
Instead of toothed gearing working in connection with a rack as just
described, various arrangements of pulleys and cords may be used,
being so arranged that the revolving motion imparted to the crank
may be made to impart the necessary to-and-fro motion to the saddle,
or that the to-and-fro motion of the saddle may be made to impart
the necessary revolving motion to the crank. For instance, a cord
might be used being attached to each end of the staff and wound
round a pulley on the saddle so that when the saddle is moved to and fro
the pully is necessarily revolved, and this revolving motion may be

page_text: transmitted to the crank by means of other pulleys and cords or by
geared wheels.
When the revolving motion of the crank is made to impart the
necessary to-and-fro motion to the saddle the wheel or pinion which
works in the rack or the pulley which works on the cord, as the case
may be, may be so arranged that it can be thrown out of gear in
order that the operator may work the crank without traversing the
saddle, and thus cause one or more blows to be struck in the same
spot, which is sometimes required in dressing a very hard place on the
stone.
By another arrang arrangement instead of carrying the chisel holder
in a guide I carry and guide it by means of a parallel motion consisting
of a pair of links of equal centres attached at one end to the chisel
holder, and at the other end to a fixing on the end of end of the
transverse slide. The parallel links are so arranged as to turn over round
a centre, so that the chisel may be by this means turned over so as
to work at one or other side of the centre of the transverse slide at
the will of the operator, and in this case I prefer to fix the guide
for the mouldings or furrows and lands in the same line as the centres
upon which the links turn, and to give it the necessary form on both
sides for dressing the furrows or mouldings.
One of the links is furnished with projections through which adjusting
screws work, which by coming in contact with one or other side of the
guide according as the chisel holder is turned over to one or other side
of the centre, the stroke or cut of the chisel is regulated.
.
Friction rollers may be arranged at each end of the moveable slide or
saddle, running on truly planed guides on the frame or staff.
I arrange the chisel holder so that the chisel may be lifted up off
the stone and kept elevated, so that when desired the saddle may
be moved without causing the chisel to cut, and in order that the
chisel may be raised off the stone when it is necessary to move the
staff after the cross slide has worked to the end of its traverse. This
may be done by forming a tail on to one of the parallel links, which on
being depressed by the thumb causes the chisel to be elevated.
Springs may be used acting on the chisel holder in such a manner as

page_text: to increase the force of the blow or accelerate the speed at which the
blows can be repeated.
In some cases in order to reduce the power required for working
the saddle to and fro a lever may be used connected to the saddle, the
lever may be of any convenient form, as for instance similar to the
handle of a pump.