IMPROVEMENTS IN MACHINERY FOR DRESSING MILLSTONES
Year: 1868

page_text: LETTERS PATENT to John Rawsthorn, of Preston, in the County of
Lancaster, Corn Miller, for the Invention of "IMPROVEMENTS IN
MACHINERY FOR DRESSING MILLSTONES."
Sealed the 9th October 1868, and dated the 30th July 1868.
PROVISIONAL SPECIFICATION left by the said John Rawsthorn at the
Office of the Commissioners of Patents, with his Petition, on the
30th July 1868.
I, JOHN RAWSTHORN, of Preston, in the County of Lancaster, Corn
Miller, do hereby declare the nature of the said Invention for "Im-
PROVEMENTS IN MACHINERY FOR DRESSING MILLSTONES," to be as follows:-
My improvements relate to an arrangement and combination of
mechanism for dressing millstones, and consists in using a hollow
cap or post which is secured by a bolt or otherwise in the centre of
the stone, and in mounting upon this centre post a bed or frame
while resting upon the stone can turn round the post as a centre
and can be secured in any required position. In the said bed or frame
a horizontal slide is arranged perpendicular to the "withs" or the
direction in which the cuts have to be made in the face of the stone,
and this slide is moved by a screw so that the cutting tool can be

page_text: advanced after each cut. Upon the end of the horizontal slide a
horizontal slideway is formed in a direction at a right angle to the
first-named slide, and upon this slideway (the face of which is vertical)
a second horizontal slide is mounted which can be moved to and fro
by hand in the line in which the cut is to be made. To the second
horizontal slide a bracket is fitted to slide vertically, and this slide is
adjustable by a screw to regulate the depth of the cut. The pick or
cutter is secured to or jointed with one end of an arm or spring, the
other end of which is carried by a pin in the said bracket or vertical
slide part and the tail of the spring, or a spring pressing upon the arm
is acted upon by an adjusting screw (also carried by the said bracket or
vertical slide part), which regulates the force or elasticity of the blow.
The pick moves in vertical guides or slides to prevent lateral vibration,
and the plane of its movement is parallel with the line of the cut, and
it is lifted by a cam working upon a stud fixed in the bracket or vertical
slide part or upon a shaft in a bearing formed therein, which cam acts
as a stop to prevent the pick from going too deep. Thus the pick is
lifted by the cam, and it is forced down to give the blow by the spring.
The cam is rotated by a band slightly elastic, which is driven by a
roller carried in arms from the first-named horizontal slide, and the
roller is driven by bevel wheels from a shaft which can slide on a key
through a bevel wheel carried by a bracket from the bed part of the
machine, which also carries a bevel wheel on a vertical stud, upon the
boss of which a grooved pulley is, which is driven by a band from
any convenient shaft. By this arrangement of machine when once
placed on the stone each "quarter" or section of the stone can be cut
without further adjustment by merely turning the bed round its centre
post, and an elastic blow can be given by the pick, the force of which
is adjustable to any required extent, and the depth of the cut can also
be regulated. In place of the pick a diamond or other rotary cutter
may be used with the same combination of slides and other parts, the
diamond cutter being arranged in bearings in place of the rotary cam
for actuating the pick.
The details of the machine may be also modified to some extent
without departing from its peculiar features; for instance, the pick may
be mounted on a vertical slide and backed by a spring, and the slide
may be actuated by an excentric or by other means, and the mode of
conveying motion to the pick or cutter may be varied.

page_text: My Invention also consists in mounting two or more picks or
rotating diamond or other cutters upon the same slides, which may be
actuated by the same or by separate cams or driving pulleys; also in
forming several cutting edges upon the same pick, or in making com-
pound picks having several cutting edges carried and actuated by the
same mechanism; also in using several diamonds or other cutters so as
to be rotated by the same shaft, and in fixing the diamonds or other
cutters in holders which can be adjusted in the shaft to and from its
axis, so that several cuts or "cracks" can be made at the same time.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Rawsthorn in the Great Seal Patent Office
on the 28th January 1869.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
RAWSTHORN, of Preston, in the County of Lancaster, Corn Miller,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Hor
Letters Patent, bearing date the Thirtieth day of July, in the year
of our Lord One thousand eight hundred and sixty-eight, and in the
thirty-second year of Her reign, did, for Herself, Her heirs and
successors, give and grant unto me, the said John Rawsthorn, Her
special license that I, the said John Rawsthorn, my executors,
administrators, and assigns, or such others as I, the said John
Rawsthorn, 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 MACHINERY FOR DRESSING MILLSTONES," upon the
condition (amongst others) that I, the said John Rawsthorn, by an
instrument in writing under my hand and seal, 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.

page_text: NOW KNOW YE, that I, the said John Rawsthorn, 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, and the accompanying two Sheets of
Drawings:-
My improvements relate to an arrangement and combination of
mechanism for dressing millstones, and consists in using a hollow cap
or post which is secured by a bolt or otherwise in the centre of the
stone to be dressed and above its surface, and in mounting upon this
centre post a bed or frame which while resting upon the surface of the
stone can be turned round the post as a centre, and can be secured
firmly to the post in any required position. In the said bed or frame
a horizontal slide is arranged to slide perpendicular to the "with" or
the direction in which the cuts or "cracks" have to be made in the
face of the stone, and this slide is moved by a screw so that the cutting
tool can be advanced after each cut so that the cuts may be made
parallel to each other. Upon one end of the horizontal slide a horizontal
slideway is formed in a direction at a right angle to the first-named
slide (the two parts forming a T), and upon this slideway, the face of
which is vertical, a second horizontal slide is mounted which can be
moved to and fro by hand in the line in which the cut is to be made.
To this second horizontal slide a bracket is fitted to slide vertically, and
this slide is adjustable by a screw to regulate the depth of the cut. The
pick or cutter is secured to one end of an arm or spring, the other end
of which is carried by a pin or fulcrum in the said bracket or vertical
slide part, and the tail of the spring or a spring pressing upon the arm
is acted upon by an adjusting screw (also carried by the said bracket
or vertical slide part), which screw regulates the force or elasticity of the
blow. The end of the pick arm or lever moves in vertical guides or
slides to prevent lateral vibrations, and the plane of its movement is
parallel with the line of the cut, and it is lifted by a cam working upon
a stud fixed in the bracket or vertical slide part, or upon a shaft in a
bearing formed therein, which cam acts as a stop to prevent the pick
from going too deep. Thus the pick is lifted by the cam, and it is forced
down to give the blow by the spring. The cam is rotated by an endless
bland slightly elastic, which is driven by a pulley sliding in a key
groove on a shaft carried in arms from the first-named horizontal slide,
and the shaft is driven by bevel wheels from a shaft which can slide on
a key through a bevel wheel carried. by a bracket from the bed part of

page_text: the machine, which also carries a bevel wheel on a vertical stud, upon
the boss of which a grooved pulley is fixed which is driven by a band
from any convenient shaft. By this arrangement of the machine when
once placed upon the stone each "quarter" or section can be cut
without further adjustment, and by merely turning the bed round its
centre post each "quarter" or section can be cut in succession, and an
elastic blow can be given by the pick, the force of which is adjustable
to any required extent, and the depth of the cut can be regulated. The
combination of the T-formed slides may be used when diamond cutters
are employed, either those which cut by the rectilinear movement simply
or those which act with this movement combined with the rotation of
the diamond like a drill, or when carried round by a small cylinder.
The details of the machine may be modified to some extent without
departing from its peculiar features, as, for instance, the pick may be actu-
ated by a crank or excentrio and a connecting rod jointed to the lever arm
or spring, the fulcrum of which may be made ad stable vertically by a
slide and screw if required; the pick may also be mounted in a vertical
slide backed by a spring, and fitted in another vertical slide actuated by
a crack or excentric, and the made of conveying motion to the pick
or cutter may be varied; for instance, this may be done by two endless
bands and jointed adjustable radial links from the sliding shaft, as will
be more particularly explained herein-after.
Fig. 1 is an elevation looking at the front of the slide carrying the
pick; Fig. 2 is a plan; Fig. 3 is an elevation looking towards the
end of the slide carrying the pick; and Fig. 4 is a sectional elevation
showing the stone and the centre post and bed or frame of the machine
in a line parallel to the slide carrying the pick, and these four views
illustrate my Invention as herein first described, and the remaining
Figures to be herein-after described illustrate modifications thereof.
x may represent the upper or lower millstone, in the centre of which
the hollow post (a) having a flange at its lower end is secured by
a bolt (a) (as shown best in Fig. 4) or other suitable means. In the
case of the lower stone the post (a) may be secured to the mill spindle
by boring a hole diametrically across the spindle head and securing
by a forked bolt and pin or by other means. The post (a) is turned
true to fit the bored out boss parts (6¹) of the frame or bed (6). There
is an annular groove (a) in the flange of the post (a) to fit the head
of a bolt (6) sliding endways through a hole in the bed or frame.
When the bed is turned round the post, the head of the bolt (62)

page_text: passes along the groove (a³), and when the bolt is tightened the bed
is firmly secured to the post. In the bed there is a slideway (6') in
which a slide (c) works perpendicular to the "with" or to the line
in which the cuts or "cracks" are required, and this slide is in one
piece with a cross slideway (d), the two forming a T piece. A screw
shaft (c) is mounted in bearings formed in brackets attached to the
slide (c), and this shaft screws through a nut in a bracket (c) secured
to the bed part (6). At the cross slide end of the screw shaft a toothed
wheel (c) is secured suitable for one of the well-known pawls (c)
which will turn over and propel the wheel either way. This pawl is
upon a stud in a lever (c) which can oscillate freely upon the screw
shaft, the length of its oscillations being limited by two pins (ce) which
are adjustable in slots formed in the bearing bracket concentric with the
screw shaft.
It is by the oscillations of this lever that the slide is moved
to give the space required between the cuts or "cracks." Or the screw
may be rotated by a catch or by change wheels instead of using the
lever and pawl above described. The shaft (c¹) can be screwed back
quickly by a crank handle which will fit upon the squares upon its
outer end. The length of the shaft and slide (c) is sufficient to give
movement to dress the "lands" of one "quarter." To steady and
give a firm bed to the slide (c) there is a projection (c) under it
near its end, and this projection and the under surface of the bed (6)
are all planed to the same level. The face of the horizontal cross
slideway (d) is vertical, and upon it a slide (e) is mounted, which
can be moved to and fro by means of the handle (e), and upon the
slide a bracket or slide (f) is mounted to move up and down, and
it is guided by vertical ribs or grooves in the slide (e), and by a pro-
jection therefrom passing through a slot in the bracket (f) which
is secured against the slide (e) by a plate (e³) and bolt (e). Small
vertical adjustments can be given to the bracket (f) by means of a
screw (f) which screws into a hole in the projection passing through
the slot in the bracket, f being the handle for turning the screw.
Upon one end of the bracket (f). a stud (f³) is fixed which forms
the fulcrum of a lever spring or arm (9), in the end of which a box
or recess (g¹) is formed in which the pick (9) is secured by a screw (9³),
and from the box there is a projecting continuation which enters
and fits a space between a part (e) and the slide (e) to form a vertical
guide to the up-and-down movements of the pick and prevent lateral
vibration. The tension of the spring lever is adjusted by the screw (9).

page_text: which works in the bracket (f) and acts upon the tail of the spring. At
the lower part of the bracket (f) there is a boss which forms the bearing
for a short shaft (h) that has a cam at one end coming under the spring
lever of the pick (as shown in dotted line in Fig. 1), and at the other end
of this shaft a grooved pulley (¹) is secured, which is driven by a endless
band (k) from a pulley (¹) sliding in a shaft (2) carried in bearings
formed in brackets (d') secured to the back part of the slideway (d), as
shown. The shaft () has a key groove from end to end, and the
pulley (k) has a groove in its boss, in which groove a fork enters, this fork
being in the end of an arm (e") secured to the slide (e), so that when the
slide is moved the pulley (*) is slided along the shaft at the same time.
The band (k) should be slightly elastic, but as the pick (92) can be adjusted
in its holder to any required depth only a very slight adjustment is
required by the screw (f), and this will have very little effect upon the
band. The shaft (2) has a bevel wheel upon its end which gears with
one on a shaft (1) at a right angle to the slideway (d). This shaft is
arranged at one end in a bearing from one of the brackets (d¹) so as to
be moved endways with the bracket, the other part of the shaft slides
through the boss of a wheel (7) having bearings in a projection from the
boss part (6) of the bed or frame, upon the top of which a flange is
secured which carries a vertical stud (m) upon which a wheel (m¹)
rotates that gears with the wheel (A), and upon the boss of the wheel
(m) a pulley (m²) is secured upon which the driving band (m³) works.
If the driving band descends or ascends to the pulley (m²) it may pass
under or over two guide pulleys (m) carried in bearings in a forked
bracket (m³) secured on the stud (m). This bracket (m") may be secured
upon the stud by a collar so as to be left free to stop in the same position
while the stud turns round in adjusting the machine from one "quarter"
to another. The mechanism may be driven from the mill spindle by using
a suitable connecting shaft passing up the centre of the hollow post (a),
and working through a bearing in the top of the hollow boss (6¹) of the
bed part, the bevel wheel (m³) being fixed upon this shaft below the
shaft (!).
Fig. 5 is a front, and Fig. 6 an edge view of an alternative method
of driving the cam or excentric working the pick. Upon the shaft (1)
or upon the boss of its bearing a link (n) is jointed, the other end of
which carries a stud (n¹) upon which a double-grooved pulley (n³)
turns freely, and to the stud (n¹) one end of another link (228) is joined,
the other end of which is jointed or turns upon the cam or excentric

page_text: shaft (n) or the boss of its bearing.
There is a grooved pulley (n) on
the shaft (), and an endless band (1) passes between this pulley and one
groove of the pulley (n³), and another endless band passes from the other
groove of the pulley (22) to the pulley (h) of the cam or excentric shaft.
The links (n and n³) are each adjustable in length by means of the slots
and bolts, as shown, to tighten the bands when required.
Fig. 7 is a detached front view showing a mode of working the pick
by a crank or excentric when the pick is mounted upon a spring lever or
arm. This arrangement is the same as that shown in Fig. 1, except that
the cam is not used. 9³ is a part made to clip upon the spring lever, and
to it one end of the rod (2) is jointed, the other end being jointed with the
crank (*) upon the end of the shaft (h) in a bearing at the upper part
of the slide (f). The whole of the spring lever (g) being made elastio
the pick strikes by its momentum when the crank is worked at sufficient
speed.
Fig. 8 is a front, and Fig. 9 is a plan showing a mode of arranging
the pick in vertical slides and working it by a crank or excentric.
d is the horizontal cross slideway; e, the slide upon which a vertical
slide (f) is secured by set screws (f*) passing through slots; f¹ is
a screw in a projection (e) from the slide (e), the point and head
of which screw fit the slot in the slide (f), so that by turning this
screw the slide and thus the pick can be adjusted vertically to the
required depth. From the top of the slide (f) there is a projection that
forms the bearing of the short shaft (h) having a driving pulley (h¹) at
one end and a crank (*) at the other end, to which one end of a rod is
jointed, the other end being jointed to a pin (½³) fixed in a slide (p)
which can slide vertically in the slide (f), and within the slide (p) there
is another vertical slide forming the tool or pick holder (g'). In this
latter slide (g) there is a screw (9), the spindle of which passes through
a hole in the slide (p), and between a shoulder on the spindle and the
under edge of the slide a helical spring (9) is placed which forces down
the tool or pick slide (g') against a stop. By turning the screw (9') a
greater or less tension can be brought upon the tool or pick slide as
required.
I have now particularly described the nature of my Invention, and the
mode of carrying the same into effect, and claim as my Invention,―
Firstly. The combination of the T-slide and slideway (c and d) with
a bed or frame (6) turning round a centre post (a) secured to the

page_text: stone (x) to be operated upon for carrying slides and tools for dressing
millstones, substantially as herein-before described.
Secondly. The mode of arranging, adjusting, and working a pick by a
cam, as herein-before described and shown by Figs. 1, 2, 3, and 4 of the
Drawings.
Thirdly. The mode of actuating a pick on a spring lever (g) or a
pick arranged in vertical slides or otherwise by a crank or excentric
when there is an elastic provision, as herein-before described and
illustrated by the Drawings.
Fourthly. The mode of conveying motion to the cams, cranks, or
excentrics working picks for dressing millstones by endless bands and
jointed links adjustable in length, as herein-before described and
illustrated by Figs. 5 and 6 of the Drawings.
In witness whereof, I, the said John Rawsthorn, have hereunto set
my hand and seal, this Twenty-seventh day of January, in the
year of our Lord One thousand eight hundred and sixty-nine.
JOHN RAWSTHORN.
(L.S.)