IMPROVEMENTS IN THE CONSTRUCTION OF MILL-STONES
Year: 1881

page_text: LETTERS PATENT to William Robert Lake, of the Firm of Haseltine, Lake,
& Co., Patent Agents, Southampton Buildings, London, for an Invention of
"IMPROVEMENTS IN THE CONSTRUCTION OF MILL-STONES." A communication
from abroad by Emil Herrmann Streitz, of Rauschmühle, near Frienwalde,
PROVISIONAL SPECIFICATION left by the said William Robert Lake at
the Office of the Commissioners of Patents on the 1st April 1881.
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent
Agents, Southampton Buildings, London. "IMPROVEMENTS IN THE CONSTRUCTION
OF MILL-STONES.' [A communication from abroad by Emil Herrmann Streitz
of Rauschmühle, near Frienwalde, Germany.]
This Invention relates to improvements in the construction of millstones.
According to these improvements the centre piece is so made as to be adjustable,
requires no dressing, and being made of hardened cast-iron is not liable to wear
away quickly. Moreover a fixed position is given to the rynd in the eye of
millstones embodying the said Invention, whilst the bush in the bed or lower stone
is also held securely by the same.
It is a well known fact that the centre piece of a mill-stone cannot be used for
grinding, but only serves for evenly distributing the material to be ground, and
consequently sand-stone, basaltic lava, and generally speaking stones of inferior
quality have very appropriately been used in the construction of such centre
pieces; only the grinding surface has been composed of pieces of the best French
stone or of similar material. Each time therefore that the grinding portions of
the millstone are dressed or its face "cracked" the centre-piece must also have its
face and furrows re-set, and thereby trouble is caused and time wasted in effecting
work which is of but secondary importance for the grinding process. By the
method hitherto practised the further disadvantage is caused, viz., that the rynd
of the runner or revolving stone has to be lowered from time to time, according to
the wear of the latter, and in addition to the work of lowering there is also the
trouble of again balancing the stone.

page_text: These disadvantages I obviate by this Invention; and in carrying the latter
into effect I construct a pair of millstones as follows, viz.:-
The upper stone or runner is made with a hollow casting of cast iron or steel,
serving as a core for the stone or grinding material, the latter being composed
preferably of pieces of the best French millstone (from Laferté sous Jouarre), which
are prepared in the ordinary manner, and are united by cement or by plaster of
Paris; hoops or bands of iron pass around the stone. To ensure a secure attach-
ment between the grinding material and the said casing or core during the
operation of grinding, a number of lugs or flanges are cast upon the latter and
take into the stone. The centre or middle piece is made of hardened cast-iron
(chilled casting), and is capable of vertical displacement in the aforesaid casing or
core. On its circumference it is provided with a number of feathers or ribs, which
take into corresponding notches or grooves in the casing, so that rotation of the
centre piece is prevented, but its vertical movement is not influenced. For exactly
regulating the centre-piece three or more strong screws are provided, which are
supported in the casing, and can be firmly held by double nuts. In the centre
piece these screws pass through strong projections, which are screw-threaded inside
the same.
I furthermore provide a rynd in the said centre-piece. It may be made in one
piece with the latter if the rynd is to be a fixed one, but it may, if preferred, be
screwed to the plate of the centre-piece, and instead of the fixed rynd a ball-rynd
or balancing rynd might be used. I also provide a clapper, which acts in the
well-known manner, and is firmly mounted in a square hole in the rynd; or
instead of this arrangement a centrifugal hopper might be used. When, instead
of the clapper, a pointed screw is placed in the aforesaid hole provided for the
former, and its point is allowed to enter the rotating part of the spindle, the runner
may be more exactly balanced.
I construct the bed or lower stone in a similar manner to that above described.
It consists of an interior casing or core, which carries an outer part, made preferably
of pieces of French millstone united as above stated by cement or plaster of Paris,
and is provided with iron hoops. The centre piece of this bed or lower stone also
slides in grooves by means of ribs so arranged that its rotation is prevented.
Three or more strong screws maintain the centre piece of the bed securely in
position in the manner described with reference to the runner.
To prevent rotation of the grinding material composed of pieces of stone, ribs or
lugs are cast upon the casing.
The above described centre piece for the bed or bottom-stone also contains a
bush, which is either cast upon the same or attached thereto by screws. Wooden
packing-wedges for the bush are firmly held by screws, and a small stuffing box
serves to prevent the passage of any of the material to be ground.
I
Either the so-called "quarter-dressing" or curvilinear dressing may be employed.
may dress with spiral, circular, or volute furrows, and the grooves or corrugations
cast upon the centre pieces must correspond with the dressing chosen for the
stone.
Only the grinding surface of my improved millstones is required to be re-dressed,
and when the dressing has been effected the centre piece is brought into proper
position. As the rynd of millstones embodying my Invention does not require to
be displaced when the stones are redressed, the "run" of the latter, when once
ascertained, can easily be maintained.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said William Robert Lake in the Great Seal Patent Office on the
1st October 1881.
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent
Agents, Southampton Buildings, London. "IMPROVEMENTS IN THE CONSTRUCTION
OF MILL-STONES." A communication from abroad by Emil Herrmann Streitz,
of Rauschmuhle, near Freinwalde, Germany.
"
This Invention relates to improvements in the construction of millstones.
According to these improvements the centre-piece is so made as to be adjustable
and to require no dressing, and being made of hardened or chilled cast iron it is
not liable to wear away quickly. Moreover a definite position is given to the .
rynd in the eye of a millstone embodying the said Invention, while the bush in
the bed or lower stone is also held securely.
It is well-known that the centre-piece of a millstone cannot be used for grinding,
but only serves for evenly distributing the material to be ground, and consequently
sand-stone, basaltic lava, and generally speaking stones of inferior quality have
very appropriately been used in the construction of such centre-pieces; the grinding
surface only has been composed of pieces of the best French stone or of similar
material. Each time therefore that the grinding portions of the millstone are
dressed the centre-piece must also have its face and furrows re-set, and thereby
trouble is caused and time wasted in effecting work which is of but secondary
importance for the grinding process. By the method heretofore practised there is
the further disadvantage that the rynd of the runner or revolving stone has to be
lowered from time to time, according to the wear of the latter, and in addition to
the work of lowering there is also the trouble of again balancing the stone.
I obviate these disadvantages by constructing mill-stones as represented in the
accompanying Drawing, in which
Figure 1 is a vertical section of a pair of my improved mill-stones.
Figure 2 represents the bed or bottom stone partly in section on the line A-B,
Figure 1, and partly in place to shew the dressing.
Figure 3 represents the runner partly in section on the line C, D, Figure 1, and
partly in plan.
Figure 4 is a plan or top view drawn to an enlarged scale of a portion of the
bed or bottom stone and its bush, and
Figure 5 is a vertical section of the same on the line E, F, Figure 4.
The upper stone or runner is provided with a hollow casing g of cast iron or
steel, which serves as a core for the grinding portion or surface of the stone. The
latter is composed preferably of pieces of the best French buhr-stone (from Laferté
sous Jouarre), which are prepared in the ordinary manner, united by cement or by
plaster of Paris, and surrounded by hoops or bands 6 of iron.
To ensure a secure attachment between the grinding material a and the casing g
during the operation of grinding, a number of lugs c are cast upon the latter, and
take into the stone, as shewn in Figures 1 and 3.
The centre or middle piece m of the stone is formed of hardened cast-iron
(chilled-casting), and is capable of vertical movement within the casing g. On its
circumference the said piece m is provided with a series of feathers or ribs o,
which enter corresponding notches or grooves in the casing g, so that the rotation
of the piece m is prevented, but its vertical movement is not impeded. For
exactly regulating the centre-piece m three or more strong screws p are provided.
These screws are supported in the casing g, and can be firmly held in position by
the double nuts 8. These screws pass through strong bosses or projections in the
centre-piece m, the said projections being screw-threaded on their interior. In

page_text: the aforesaid centre-piece I also provide a rynd E. In the Drawing this rynd is
shewn as formed in one piece with the said centre-piece, the said rynd being
supposed to be a fixed one, but if desired it may be screwed to the plate of the
centre-piece, and instead of the fixed rynd a ball-rynd or balancing rynd may be
used. J is the clapper, which acts in the usual manner, and is firmly mounted in
a square hole in the rynd E; instead of this arrangement a centrifugal hopper
might be used. If instead of the clapper J a pointed screw is placed in the hole
provided for the said clapper, and its point is allowed to enter the rotating part of
the spindle W; the runner may be more exactly balanced.
The bed or bottom stone I construct in a similar manner to that above described,
that is to say, it consists of an interior casing g¹ which carries the outer part a',
made preferably of pieces of French buhr united as above stated by cement or
plaster of Paris, and provided with iron hoops. The centre piece m¹ is also
provided. with projections or feathers o¹, which enter grooves in the casing g¹ to
prevent the rotation of the said piece. Three or more strong screws p¹ maintain the
said centre piece m¹ securely in position in the same manner as that described with
reference to the runner. To prevent the rotation of the grinding portion a³,
composed of pieces of stone, ribs or lugs z¹ are cast upon the casing g'.
The above described centre-piece m¹ for the bed or bottom stone also contains
the bush H, which is either cast upon the same, as shown, or attached thereto by
screws. The wooden packing-wedges v for the bush are firmly held by screws k¹,
and a small stuffing box u¹ serves to prevent the passage of any of the material to
be ground.
As to the dressing of the stone, either the so termed "quarter-dressing" may be
employed, as illustrated, or curvilinear dressing may be used, and I may dress with
spiral, circular, or volute furrows. The grooves or corrugations cast upon the
centre-pieces must correspond with the dressing chosen for the stone. Figure 5
represents a sectional profile of a centre-piece as suited for "quarter-dressing."
As above stated the grinding surface only of my improved mill-stones requires
to be re-dressed, and when the dressing has been effected the centre-piece is
brought into the proper position by means of a ruler or in any other suitable
manner.
By the arrangement of the rynd and bush, as above described, the necessity for
re-setting when the stone wears is obviated, and consequently the parts always
retain their proper position.
Having thus fully described the said Invention as communicated to me by my
foreign correspondent, and the manner of performing the same, I wish it understood
that I claim,-
First. A mill-stone provided with the hardened or chilled cast core or centre-
piece capable of vertical adjustment within an iron casing, to which the grinding
part of the stone formed of French or other suitable buhr is attached, substantially
as above set forth.
Second. The rynd and bush arranged in the manner described, and rendered
practicable by the construction set forth in the foregoing claim, whereby the said
rynd and bush are carried upon the hard or chilled movable centre-pieces, so that
the necessity for re-setting when the stone wears is obviated, and consequently the
parts always maintain their proper position.
In witness whereof, I, the said William Robert Lake, have hereunto set my
hand and seal, this First day of October, in the year of our Lord One
thousand eight hundred and eighty one.