IMPROVEMENTS IN DRESSING MILLSTONES, AND IN APPARATUS THEREFOR
Year: 1868

page_text: LETTERS PATENT to Robert Young, of Glasgow, in the County of
Lanark, North Britain, Engineer, for the Invention of "IMPROVE-
PROVISIONAL SPECIFICATION left by the said Robert Young at the
Office of the Commissioners of Patents, with his Petition, on the
24th July 1868.
I, ROBERT YOUNG, of Glasgow, in the County of Lanark, North
Britain, Engineer, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN DRESSING MILLSTONES, AND IN APPARATUS THEREFOR," to
be as follows, that is to say:-
This Invention relates to improvements in connection with apparatus
for dressing millstones such as is described in the Provisional Specifi-
cation lodged with an application for Letters Patent by the present
applicant on the 12th February 1868 (No. 475), but the present
improvements are also more or less applicable with other arrangements
for dressing millstones.

page_text: Two modes of using diamonds or such like hard stones are in use
or have been proposed for dressing millstones, and whilst by one mode a
fine or minute groove is produced by giving the diamond a simple
rectilinear motion along the surface of the stone, by the other mode a
similar groove is made by imparting a rapid rotation to the diamond
whilst it is moved along the stone. The latter more complex plan has
been adopted because ordinary diamonds have not been found to act
satisfactorily when set to cut with a simple rectilinear movement. By
the present Invention however the simpler rectilinear movement is
made to answer satisfactorily by applying a particular kind of diamond,
namely, what is ordinarily called the black diamond or carbon, and is
met with in Brazil, Siberia, and elsewhere in the form of small rough
dark or dull-colored stones. The action of the tool is further improved
by introducing a layer of rubber or other suitable elastic material
between the actual diamond holder and the slide which carries and
guides it, so as to prevent its being absolutely rigid.
Another improvement consists in arranging the tool to cut in both
directions in each groove, whereby the groove is better formed, whilst
the apparatus may be simplified as the arrangements previously proposed
for lifting the tool during each return stroke can be dispensed with.
In some modifications of the apparatus described in the earlier
Provisional Specification herein-before referred to the arm holder is
found to require steadying when the guide arm on which the tool holder
slides is near either end of it, and the requisite steadyness is by the
present Invention secured by applying at or near the end of the arm
holder a loaded foot to rest on the surface of the stone, and which is
bolted to the holder with an interposed layer of rubber or other suitable
elastic material, so that any slight adjustment that may be required
may be effected by screwing up the elastic layer more or less.
The present Invention also comprises an improved mode of fixing
the diamond, which consists in making the holder of three or more
angular pieces of metal shaped to fit together and with the angles which
meet cut away or slightly hollowed to receive the diamond. The several
pieces are made adjustable by separate screws, so that the diamond, of
whatever shape it may be, can be firmly gripped in any position.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Robert Young in the Great Seal Patent Office on
the 30th November 1868.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ROBERT
YOUNG, of Glasgow, in the County of Lanark, North Britain, Engineer,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-fourth day of July, in the year
of our Lord One thousand eight hundred and sixty-eight, in the thirty-
second year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Robert Young, Her special licence that I,
the said Robert Young, my executors, administrators, and assigns, or
such others as I, the said Robert Young, 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 DRESSING MILLSTONES,
AND IN APPARATUS THEREFOB," upon the condition (amongst others) that I,
the said Robert Young, my executors or administrators, by an instru-
ment 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 Robert Young, 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 in writing, reference being had to the accom-
panying Drawings, that is to say :-
My said Invention relates to improvements in connection with
apparatus for dressing millstones such as is described in the Provisional
Specification relative to certain Letters Patent granted to me, the said
Robert Young, and dated the 12th February 1868 (No. 475), but the

page_text: present improvements are also more or less applicable with other
arrangements for dressing millstones.
Two modes of using diamonds or such like hard stones are in use
or have been proposed for dressing millstones, and whilst by one mode a
fine or minute groove is produced by giving the diamond a simple
rectilinear motion along the surface of the stone, by the other mode a
similar groove is made by imparting a rapid rotation to the diamond
whilst it is moved along the stone. The latter more complex plan has
been adopted because ordinary diamonds have not been found to act
satisfactorily when set to cut with a simple rectilinear movement. By
my present Invention however the simpler rectilinear movement is made
to answer satisfactorily by applying a particular kind of diamond,
namely, what is ordinarily called the black diamond or carbon, or bort,
and is met with in Brazil, Siberia, and elsewhere in the form of small
rough dark or dull-colored stones. The action of the tool is further
improved by introducing a layer of rubber or other suitable elastic
material between the actual diamond holder and the slide which carries
and guides it, so as to prevent its being absolutely rigid.
Another improvement consists in arranging the tool to cut in both
directions in each groove, whereby the groove is better formed, whilst
the apparatus may be simplified as the arrangements previously
proposed by me for lifting the tool during each return stroke can be
dispensed with.
And in order that these and other improvements comprised in my
present Invention may be properly understood I have hereunto appended
a Sheet of explanatory Drawings to be herein-after referred to, and
representing a modification of millstone dressing apparatus made accord-
ing to my earlier Patent herein-before referred to, and also including
my present improvements.
Figure 1 is a plan of my dressing apparatus as applied upon a mill-
stone, and Figure 2 is a corresponding vertical section, whilst Figure 3
is an end elevation of the movable guide or arm; Figure 4 is an inverted
plan of the bottom of the tool or diamond holder, and Figures 5 and 6
are an end and a front elevation of the slide, as fitted with a single tool,
whilst Figures 7 and 8 are sectional elevations of a modification of the
slide fitted with two tools.

page_text: The framing of the machine consists of a central boss 1 made hollow
to go over the head of the millstone spindle when operating on the bed
stone, and this boss is connected by arms 2 to a segmental ring 3
accurately turned or otherwise made flat on its under side to rest on the
surface of the millstone 4 near the outer edge thereof, that being the
part of the millstone surface which can be most relied upon as being
truly level. To facilitate the placing of the frame on the stone three
adjustable claws 5 are fixed on the segmental ring 3, and catch upon the
top binding hoop; accurate centering however of the frame on the stone
is not essential. Two of the frame arms 2 are made in the same line
tangential to the boss, and to them there is fixed a horizontal guide 6
made with V rails to receive a saddle 7, which can be moved along the
guide 6 by means of a screw spindle 8. A horizontal arm 9 is fixed to
the saddle 7, so as to stand out at right angles from the guide 6, and this
arm is made with horizontal V rails to guide a slide 10, in which is
adjusted the tool or diamond holder 11. The diamond holder 11 is a
spindle screwed at its upper end to receive a nut, and formed at its
lower end with a cross plate to fit a rebate in the bottom of the slide 10,
and with a boss, in which a socket is bored to receive three angular
steel bits, by which the diamond is fixed. The three steel bits are
shaped to build together into a cylindrical form a little less than the
socket, and the bottom corners of their central meeting edges are
hollowed to grip the diamond, whilst they are adjusted upon it by
screws tapped through the sides of the socket. With this simple
construction the diamond can be gripped in any position by the steel
bits, and the whole can be turned in the socket, so as to present the
cutting angle of the diamond in the most advantageous manner. One
or two plies of vulcanised rubber a are applied between the bottom
cross plate of the tool 11 and the slide 10, and may be more or less
compressed to modify the elastic action by means of the screw nut
which holds the tool in the slide. A handle 12 is jointed upon the
slide 10, and by means of it the operator draws the slide along the
guide arm 9, and so causes the diamond to cut a minute groove on
the surface of the millstone. The dressing for one sector of the millstone
surface is done with the frame 1, 2, 3, in one position, the arm 9 being
shifted or fed across after the formation of each groove by means of the
screw spindle 8. Toothed feed wheels 13 are fixed on the ends of the
screw spindle 8, and are acted upon by feed catches jointed to levers 14,
set loosely on the spindle and connected by a horizontal rod 15 above.

page_text: A handle 16 is set loosely on the rod 15, so that it can be moved into
the most convenient position for the operator who works the tool slide 10
with one hand, and the feed handle 16 with the other. The feed may
be effected either when the slide 10 is at the inner end of its traverse
or when it is at the outer end thereof, the diamond being moved in
both directions along each groove, or the feed may be effected both when
the slide is at the inner end and when it is at the outer end of its
traverse, in which case the diamond will be moved only once along
each groove. When the dressing of one sector of the millstone surface is
completed the entire machine is shifted round to bring the arm 9 parallel
to the grooves of the next sector.
As stated in the Specification of my earlier Patent, herein-before
referred to, two diamonds with their holders may be carried on the
slide 10, as shown in Figure 8; and this modification may be used when
a deeper cut is required than that which a single diamond will give,
one of the two diamonds being adjusted slightly lower than the other.
When applying two tools in this way I fit the spindles somewhat loosely
into the slide 10, and place small cushions 6 of vulcanised rubber behind
them whilst I insert small pinching screws c in front, and can by
turning these more or less adjust the two diamond points so as to cut
accurately in the same line. The two tools may also be adjusted to cut
in two separate lines if preferred.
In my Provisional Specification lodged on applying for the herein-
before in part recited Letters Patent I described the application of an
adjustable foot for steadying the arm 9, but I find such an adjustable
foot unnecessary, and that it is in fact better as well as simpler to make
a part of the bottom of the arm 9 bear on the surface of the stone, as
shown at d in Figure 2.
Having thus particularly described my said Invention, and the manner
in which the same is to be performed, I have to state that I do not
restrict myself to the precise details herein described and delineated; but
that what I believe to be novel and original, and claim as the Invention
secured to me by the herein-before in part recited Letters Patent is,―
1. The applying of the black diamond for dressing millstones with a
simple rectilinear cut, as herein-before described.
2. The fixing of the diamond by means of three or more angular bits
held and adjusted substantially as herein-before described.

page_text: 3. The applying of vulcanised rubber to prevent absolute rigidity in
the tool, substantially as herein-before described.
In witness whereof, I, the said Robert Young, have hereunto set
my hand and seal, this Twenty-eighth day of November, in
the year of our Lord One thousand eight hundred and sixty-
eight.
Witness,
EDMUND HUNT,
Patent Agent,
Glasgow.
ROBERT YOUNG. (L.S.)