IMPROVE MENTS IN THE GRINDING SURFACE OF MILLSTONES, AND IN APPARATUS OB MACHINERY FOR FORMING THE SAME
Year: 1868

page_text: LETTERS PATENT to Augustus Bryant Childs, of No. 16, Mark Lane,
in the City of London, Engineer, for the Invention of "IMPROVE
MENTS IN THE GRINDING SURFACE OF MILLSTONES, AND IN APPARATUS OB
MACHINERY FOR FORMING THE SAME."
Sealed the 17th October 1868, and dated the 18th April 1868.
PROVISIONAL SPECIFICATION left by the said Augustus Bryant Childs
at the Office of the Commissioners of Patents, with his Petition,
on the 18th April 1868.
I, AUGUSTUS BRYANT CHILDS, of No. 16, Mark Lane, in the City of
London, Engineer, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN THE GRINDING SURFACE OF MILLSTONES, AND IN APPARATUS
OR MACHINERY FOR FORMING THE SAME," to be as follows :-
The said Invention relates to dressing millstones for grinding grain
or corn and other substances, and the objects of the said Invention are,
first, to give to such stones an improved "dress" or "crack" or grinding

page_text: surface; and, secondly, to diminish the labor and cost of dressing or
cutting such surface, and to allow it to be accomplished rapidly instead
of in the present slow and tedious manner.
The nature of my Invention consists, first, in the peculiar formation
of the serrations or grooving on the surface of the millstone. Hitherto
such grooving, which is known as the "dress" or "crack" has been
formed in straight lines parallel to the furrows of the stone. Instead
of forming the grooves or serrations in the above manner I cut or plane
spiral grooves in the face of the stone. The said spiral grooves extend
from the breast or centre of the stone to its skirt or periphery, the
grooves being so arranged that when a pair of stones are working
together the grooves in one are never coincident with those in the
other stone, but cross each other, forming acute angles together at the
edges, which have a drawing or shaving cutting action upon the grain.
When the spiral grooves extend from the breast or centre toward the
periphery of the stone in one direction an outward draught will be pro-
duced, whereby the grain will be quickly carried to the periphery of
the stone, but by cutting such spiral grooves in the reverse direction on
the surface of the stones a retarding action is produced upon the grain.
The stones may also be cut with the grooves arranged to produce a
retarding motion on one stone, and an outward or progressive motion
on the other. Instead of dressing the stones with spiral grooves or
serrations I sometimes form the grooves or "crack" in straight or
serpentine lines, but instead of making them parallel with the furrows
I make them at right angles or nearly so thereto.
My Invention consists, secondly, in automatic machinery or apparatus
of novel construction, whereby the dressing of the millstones in the
manner above described is rapidly and conveniently effected. A diamond
or other suitably hard mineral substance is fixed in a holder attached to
a carriage fitted to travel upon horizontal arms which are keyed upon a
vertical spindle or shaft supported in the central socket or boss of a
frame which is fixed over or on the stone to be dressed; upon the under
side of this socket is fixed a stationary worm or screw. Worm wheels
carried on spindles extending endwise along the arms are geared into
the said worm. The outer extremity of each of these spindles carries a
small spur wheel which gears into another spur wheel fixed on a screw
which extends from end to end of the arm, and which is fitted to a
nut attached to the tool carriage. When the vertical spindle with its

page_text: horizontal arms revolves the worm wheels which are geared with the
fixed worm, and whose spindles turn with the said shaft and arms, are
caused to rotate on their axes at a speed depending upon the relative
proportion of the number of teeth in the wheels and the said fixed
worm. The motion of these worm wheels is through the spindle and
spur wheels imparted to the feed screw, which may be arranged to
propel the tool carriage either towards or from the centre of the stone.
The pitch or distance between each turn of the spiral groove in the
stone may be regulated by varying the proportion of the worm wheels
and the fixed worm, or by varying the relative size of the spur wheels
or the pitch of the feed screw. If the vertical shaft or spindle is driven
at one unvarying speed the velocity of the cutting tool upon the surface
of the stone will increase or diminish as the said tool moves outward
or inward upon the horizontal arms. To prevent this change in the
velocity of the tool the speed of the vertical shaft is caused to increase
or diminish as the said tool changes its position. I prefer to produce
this varying motion of the vertical shaft by means of a pair of conical
pulleys, one of which is fixed on an intermediate shaft connected with
the vertical shaft, the other pulley being fixed on any convenient driving
shaft. The said pulleys are arranged in reverse directions, as is well
understood, and the belt passing over them is caused by a screw or
other device to travel endwise on the said pulleys to vary the speed of
the vertical shaft.
When it is desired to dress the stones with the grooves or "crack "
in straight or curved lines at right angles to the furrows, the gearing
and feed screw of the apparatus must be arranged to impart to the tool
a motion in straight or curved lines of any desired length instead of in
acontinuous spiral direction.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Augustus Bryant Childs in the Great Seal Patent
Office on the 17th October 1868.

page_text: WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eighteenth day of April, in the year
of our Lord One thousand eight hundred and sixty-eight, in the thirty-
first year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Augustus Bryant Childs, Her special
licence that I, the said Augustus Bryant Childs, my executors, adminis-
trators, and assigns, or such others as I, the said Augustus Bryant Childs,
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 of
"IMPROVEMENTS IN THE GRINDING SURFACE OF MILLSTONES, AND IN APPARATUS
OR MACHINERY FOR FORMING THE SAME," upon the condition (amongst others)
that I, the said Augustus Bryant Childs, my executors or adminis-
trators, 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 Augustus Bryant Childs, 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 accompany-
ing Drawings forming a part of this Specification :-
The said Invention relates to dressing millstones for grinding grain or
corn and other substances, and the objects of the said Invention are,―
First. To give to such stones an improved "dress" or "crack" or
grinding surface.
And secondly. To diminish the labour and cost of dressing or cutting
such surface, and to allow it to be accomplished rapidly instead of in
the present slow and tedious manner.
Instead of cutting the grooves or serrations which form the "dress"
or "crack" in the ordinary manner, I cut or plane spiral grooves in
one or both directions in the face of the stone. The said spiral grooves
extend from the breast or centre of the stone to its skirt or periphery,

page_text: the grooves being so arranged that when a pair of stones are working
together the grooves in one are never coincident with those in the other
stone, but cross each other, forming acute angles together at the edges
which have a drawing or shaving cutting action upon the grain.
When the spiral grooves extend from the breast or centre towards
the periphery of the stone in one direction an outward draft will be
produced, whereby the grain will be quickly carried to the periphery
of the stone, but by cutting such spiral grooves in the reverse direction
in the surface of the stone a retarding action is produced upon the
grain. The stones may also be cut with the grooves arranged to produce
a retarding motion on one stone and an outward or progressive motion
on the other. Instead of dressing the stones with spiral grooves or
serrations I sometimes form the grooves or
"crack" in straight or
serpentine lines, but instead of making them parallel with the furrows
I make them at right angles or nearly so to the same.
I employ automatic machinery or apparatus of novel construction
whereby the dressing of the millstones in the manner above described
is rapidly and conveniently effected. A diamond or other suitably hard
mineral substance is fixed in a holder attached to a carriage which is
fitted to travel upon horizontal arms keyed upon a vertical spindle or
shaft supported in the central socket or boss of a frame which is fixed
over or on the stone to be dressed. Upon the under side of this socket
is fixed a stationary worm or screw; worm wheels carried on spindles
extending endwise along the arms are geared into the said worm. The
outer extremity of each of these spindles carries a small spur wheel
which gears
into another spur wheel fixed on a screw which extends
from end to end of the arm and which is fitted to a nut attached to
the tool carriage. When the vertical spindle with its horizontal arm
revolves, the worm wheels which are geared with the fixed worm, and
whose spindles turn with the said shaft and arms, are caused to rotate
on their axes at a speed depending upon the relative proportion of the
number of teeth in the wheels and the said fixed worm. The motion
of these worm wheels is through the spindle and spur wheels imparted
to the feed screw, which may be arranged to propel the tool carriage
either towards or from the centre of the stone.
The accompanying Drawings illustrate the said machinery constructed
and arranged for producing two spiral grooves crossing each other upon
the face of the stone.

page_text: Figure 1 is a half plan of my improved machinery showing the same
arranged on the face of a millstone; Figure 2 is a side elevation of
the same; Figure 3 is a section on the line x, x, Figure 2; Figure 4
illustrates detached portions of the said machinery drawn to an enlarged
scale. Like letters indicate the same parts throughout the Drawings.
The frame a is constructed of cast iron or other suitable material and
of the required size and strength. The feet a¹ of the said frame are
secured by bolts 6 or by other suitable fastenings to the plate cor
other support upon which the stone A lies. The said stone is held
and adjusted upon the bed by means of the screws d and e.
The
vertical spindle or shaft is supported in the bearing or step g, and is
fitted to turn freely in the boss a³ of the frame a, which boss is arranged
over the centre of the stone. The stationary worm his cast upon or
otherwise securely fixed upon the lower part of the boss a³. The
worm wheels i which gear into the said worm are keyed or otherwise
firmly secured upon the horizontal spindles j, the said spindles being
supported so as to turn freely in the brackets which project from
the arms k. The spur wheels 1, one of which is carried on the outer
end of each of these horizontal spindles gear into the pinions m on the
screws n which pass through the nuts o of the tool carriages p, whose
construction is clearly illustrated in Figure 4. The said carriages are
constructed with the vertical holder q, which carries the diamond r
or other mineral substance employed as the cutting tool or point. The
said holder is fitted into the socket p¹, and is secured therein
by a set screw p³. The screw p³ serves to adjust the tool - upon
the face of the stone. The horizontal arms k are formed with dove-
tailed projections, and the carriages p are fitted to slide freely
endwise on these projections. The pitch or distance between each
turn of the spiral groove on the stone may be regulated by varying
the proportion of the worm wheels i to the fixed worm h, or by varying
the relative size of the spur wheels and m, or by using feed screws
of different pitch. It is also necessary that the vertical shaft or spindle
should be driven with a varying speed, otherwise the velocity of the
cutting tool upon the surface of the stone will increase or diminish as
the said tool moves outward or inward upon the horizontal arms k.
To prevent this change in the velocity of the tool r, the speed of the
vertical shaft f is caused to increase or diminish as the said tool changes

page_text: its position. I prefer to produce this varying motion of the vertical
shaft by means of a pair of conical pulleys, one of which is fixed on
an intermediate shaft connected by bevel or other wheels with the
vertical shaft f, the other pulley being fixed on any convenient driving
shaft parallel to the intermediate shaft. The said pulleys are connected
by a strap or belt, and are arranged in reverse directions, as is well under-
stood, so that by moving the belt laterally upon the pulleys the speed
of the intermediate shaft is increased or diminished, and the speed of
the vertical shaft f is varied as desired. This adjustment of the belt
may be effected by means of a screw or other suitable shifting device.
When it is desired to dress the stones with a spiral groove in one
direction only, one of the tool holders and carriages with its operative
gearing will be required. When the stone is to be dressed with the
grooves or "crack" in straight or curved lines at right angles to the
furrows the gearing and feed screws of the apparatus may be readily
proportioned and arranged to impart to the tool a motion in either
straight or covered lines of any desired length instead of in a continuous
spiral direction.
Having thus fully described my said Invention, and shown what I
consider to be the most convenient method of carrying the same into
practise, I claim,--
First. Dressing or cutting millstones in the manner set forth by a
diamond or other hard mineral substance which is moved over the face
of the stone by a sliding carriage carried on a horizontal arm, the motion
of which carriage is produced by means of a fixed worm geared in
connection with the feed screw, substantially as set forth.
Second. The combination of two of such rotating arms, sliding
carriages, and mineral cutters, for the purpose set forth.
In witness whereof, I, the said Augustus Bryant Childs, have
hereunto set my hand and seal, this Seventeenth day of October,
in the year of our Lord One thousand eight hundred and sixty-
eight