AN IMPROVED MODE OF APPARATUS FOR DRESSING MILLSTONES.
Year: 1868

page_text: LETTERS PATENT to John Wallis, of Greenwich, in the County of
Kent, Miller, for the Invention of "AN IMPROVED MODE OF
APPARATUS FOR DRESSING MILLSTONES.'
"
Sealed the 4th August 1868, and dated the 10th March 1868.
PROVISIONAL SPECIFICATION left by the said John Wallis at the
Office of the Commissioners of Patents, with his Petition, on the
10th March 1868.
I, JOHN WALLIS, of Greenwich, in the County of Kent, Miller, do
hereby declare the nature of the said Invention for "AN IMPROVED MODE
OF AND APPARATUS FOR DRESSING MILLSTONES," to be as follows:-
Instead of dressing the face of the millstones in a series of straight
lines arranged in the well-known manner I propose to make on the
working face a series of curved lines arranged as a convolute, starting
from the eye or near the centre of the millstone, and terminating near
the periphery.
The cutting tool which I prefer to use in carrying out my Invention
is a diamond or other hard stone or stones set in a holder, which is
secured in any convenient manner in a slide rest mounted in a longi-
tudinal frame provided with an eye, which fits over a central spindle in
the eye or near the centre of the millstone. This longitudinal frame is
made long enough to admit of the slide rest or holder being moved

page_text: radially from the centre to the periphery of the millstone. The slide
with the holder of the cutting tool is made to move on guides, whereby
it is kept steady, and the holder retained in a vertical position. A long
screw, as in the slide rest of an ordinary lathe, passes through a female
screw tapped in the rest or tool holder, so that by turning the screw the
rest or holder of the tool may be moved along its guides in a radial
direction from the central part or eye of the millstone when the appa-
ratus is in its proper place on the stone. In order to dress the stone the
longitudinal frame with the rest or holder and tool secured therein is
moved round the central pin, and the diamond or cutting tool being
made to press on the face will cut into the stone a curved line all round.
A stud or pin is fixed at any convenient point beyond or just outside
the periphery of the millstone, and a tappet wheel on the outer end
of the screw of the slide rest comes against the stud or pin every time
the apparatus is brought round to it, and thus causes the screw to turn
on its axis, and thereby to move the rest or holder a short distance along
its guides, so that on the succeeding revolution of the apparatus round
the central pin the cutting tool will be made to operate upon a fresh
part of the stone. It will now be understood that every time the cutting
tool comes round to the fixed pin or stud it will be shifted a little further
from the centre of the stone, and will thus be made to cut a convolute
curve in the face of the millstone. The faces both of the runner and
the bed stone are dressed in the same manner, and if desired the central
pin or pivot round which the frame is made to rotate may be placed
excentrically in either one or both stones so that the convolute lines on
the faces of the stones will be made to intersect or cross each other
when the stones are at work.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Wallis in the Great Seal Patent Office on
the 10th September 1868.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
WALLIS, of Greenwich, in the County of Kent, Miller, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Tenth day of March, in the year
of our Lord One thousand eight hundred and sixty-cight, in the thirty-

page_text: first year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said John Wallis, Her special licence that I,
the said John Wallis, my executors, administrators, and assigns, or such
others as I, the said John Wallis, 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 "AN IMPROVED MODE OF AND APPARATUS FOR DRESSING
MILLSTONES," upon the condition (amongst others) that I, the said
John Wallis, my executors or administrators, by an instrument in
writing under my, or their, or one of their hands and seals, 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.
NOW KNOW YE, that I, the said John Wallis, 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, reference being had to the Drawing hereunto
annexed, and to the letters and figures marked thereon (that is to
say):
-:
According to my Invention of "An Improved Mode of and Apparatus
for Dressing Millstones," instead of dressing the face of the millstones
in a series of straight lines arranged in the well-known manner I make
on the working face of the stone a series of curved lines arranged as a
convolute, starting from the eye or near the centre of the millstone, and
terminating near the periphery.
In the accompanying Drawing, Fig. 1 represents an elevation of the
apparatus adapted to a millstone for the purpose of dressing the face
according to my Invention; Fig. 2 is a plan view of the same, shewing
the curved arrangement of the lines a, a, that are being cut in the face
of the stone A by my improved apparatus, which consists of a central
vertical shaft b, which may be rotated in any convenient manner. On
to this central shaft 6 is keyed or fimly secured the longitudinal lever
frame c, which carries the slide rest d and cutting tool holder e, shewn
detached on an enlarged scale at Figures 3.
The cutting tool which I prefer to use in carrying out my Invention

page_text: is a diamond or other hard stone or stones set in a holder, such as that
shewn at Figures 3, and hereafter more particularly described. This
holder is secured in any convenient manner in the tool holder or slide
rest d mounted in the longitudinal frame c. The central spindle b
rests in a step f, and this step is secured by screws to a centre pin in the
eye or near the centre of the millstone. The longitudinal frame c is made
long enough to admit of the slide rest or holder d being moved radially
from the centre to the periphery of the millstone. The slided with the
holder e of the cutting tool is made to move on guides c¹, c¹, in the
frame c, whereby it is kept steady and the holder e retained in a vertical
position. A long screw 9, Fig. 1 (as in the slide rest of an ordinary
lathe), passes through a female screw tapped in the rest or tool holder d,
so that by turning the screw g by means of the handle g₁ at its outer
end the rest or tool holder d of the tool may be moved along its
guides c¹, c, in a radial direction from the central part or eye of the
millstone A when the apparatus is in its proper place on the stone. In
order to dress the stone the longitudinal frame c with the rest or tool
holder d and tool secured therein is moved round the central step f
secured within the eye of the millstone, and the diamond or cutting
tool e being made to press on the face of the stone will cut into the
stone a curved line all round, as shewn at a, a, a, Fig. 2. Studs, pins, or
stops are fixed at any convenient point either just outside the periphery
of the millstone or on the foundation plate of the step ff, as shewn
at i, i, Figures 1, 2, and 4. A tappet wheel on the end of the screw g
of the slide rest comes against these studs or pins every time the lever
arm and tool holder are brought round to them, and thus the screw g
is caused to turn on its axis, and thereby to move the rest or tool
holder d a short distance along its guides c¹, c¹, so that on the suc-
ceeding revolution of the apparatus round the central step f, the cutting
tool e will be made to operate upon a fresh part of the stone. It will
now be understood that every time the cutting tool comes round to
either of the fixed pins or studs it will be shifted a little further from
the centre of the stone, and will thus be made to cut a convolute curve
in the face of the millstone. The mode of securing the diamond in
the holder will be best understood by referring to the detached view of
the holder, Figures 3. The shank of the holder consists of a square stem
of iron k, half of the lower end of which is removable as shewn at
k, Fig. 3*, but when in its place is secured by screws 1, 1. A hole m is
drilled up the end of the tool, and is filled with a soft metal or alloy,

page_text: such as is used for the bearings of machinery, and consists of a mixture
of tin, zinc, and antimony. In order to secure the diamond in its
setting the part ¹ is removed, and after making a nick or recess in the
lower end of the soft metal setting the diamond is placed therein, and
the two parts of the holder are screwed together so as to nip the diamond
between the two pieces of soft metal, as shewn at Fig. 3. The faces
both of the runner and the bed stone are dressed in the same manner,
and if desired the central pin or pivot round which the frame is made to
rotate may be placed excentrically in either one or both stones, so that
the convolute lines on the faces of the stones will be made to intersect
or cross each other when the stones are at work.
.
Figures 1 and 2 represent the apparatus adapted to the top stone or
runner, but in order to adapt the apparatus to the bed stone a somewhat
different description of step must be made for the central spindle b.
This modification is shewn in the sectional view, Fig. 4, in which the
step ffits over a central pin h of the bed stone. It will be seen that
the step is provided with adjusting screws f¹, f, for the purpose of
adjusting its position and fixing it.
Having now described my Invention of "An Improved Mode of and
Apparatus for Dressing Millstones," and having explained the manner of
carrying the same into effect, I claim as the Invention secured to me by
Letters Patent as aforesaid,―
First. Dressing millstones in curved lines as herein set forth instead of
in straight lines as heretofore.
Second. I claim the machine shewn in the Drawings, whereby the
cutting tool e with the diamond secured therein as herein set forth may
be carried round and made to travel over and cut into the surface of the
millstone in a convolute curve, in the manner and for the purpose herein
set forth.
In witness whereof, I, the said John Wallis, have hereunto set my
hand and seal, the Fifth day of September, in the year of our
Lord One thousand eight hundred and sixty-eight.
JOHN WALLIS. (L.S.)