IMPROVEMENTS IN THE MANUFACTURE OF FACTITIOUS MILLSTONES AND OTHER GRINDING OR RUBBING SURFACES."AL SP
Year: 1879

page_text: LETTERS PATENT to Gustav Adolph Buchholz, of Potsdam, in the Empire of
Germany, but temporarily of Chancery Lane, in the County of Middlesex,
Engineer, for the Invention of "IMPROVEMENTS IN THE MANUFACTURE OF
FACTITIOUS MILLSTONES AND OTHER GRINDING OR RUBBING SURFACES."
PROVISIONAL SPECIFICATION left by the said Gustav Adolph Buchholz at
the Office of the Commissioners of Patents on the 21st January 1879.
GUSTAV ADOLPH BUCHHOLZ, of Potsdam, in the Empire of Germany, but
temporarily of Chancery Lane, in the County of Middlesex, Engineer.
"LM-
PROVEMENTS IN THE MANUFACTURE OF FACTITIOUS MILL STONES AND OTHER
GRINDING OF RUBBING SURFACES."
This Invention relates to the manufacture of an efficient substitute for what are
known as French burrs, and also for the steel blades used in hulling machinery. In
manufacturing, for example, a factitious top or runner millstone according to this
Invention, I mould the same in a plastic material, which is a preparation of porcelain
clay that will, when fired, possess a porous character throughout. Into this clay,
prepared in the way well known to potters, I knead small seeds or grain, obtained
preferably from the siftings of wheat, or pieces of wood, or pasteboard, or other
combustible material, which may be cut into the required size and rounded or
shaped by a pearl barley mill, and I thus ensure an even distribution through the
mass of small portions of carbonaceous matter.
With this composition I mould the back of the mill stone, forming in the eye
thereof an internal flange, which will be required for fixing the runner to its spindle,
and upon this back, when inverted, I build up what may be termed the grinding
surface or that portion of the stone which is intended to act upon the corn required
to be ground, or the two parts may be moulded together.
The thickness of this grinding portion of the stone will in general measure from
10 to 15 inches, more or less, according to the diameter of the grinders, and I form
it in segment pieces in the following manner :-
Each segment piece I build up separately, commencing with one vertical side
thereof. This side will consist of a thin layer of the before mentioned plastic com-
pound, its shape corresponding to the vertical section of that part of the stone
which is destined to perform the grinding action, and to wear away under the
continuance of such action. Upon this layer of plastic composition, which takes

page_text: the form of the bed on which it is placed, I lay a similarly shaped piece of paste-
board pierced with rows of holes, and leaving continuous parallel lines of the
unpierced pasteboard. These holes I now fill with the clay composition, and over
this pasteboard I place a second evenly rolled thin layer of the plastic compound,
which will be joined to the first layer through the clay filling of the pierced paste-
board. Upon this second layer is placed another piece of pierced pasteboard,
which, when filled up with clay, receives in its turn a layer of the plastic compound,
and by applying alternate layers of these substances, adjusting their length to suit
the form required, a block of suitable tapering shape will be produced.
When a suitable number of these blocks to cover the back portion of the stone is
formed I set them in place, and subject the now moulded millstone, after air drying,
to the heat of the potter's oven.
The result of this firing will be to harden the clay and to burn out all the carbon-
aceous matter combined therewith. Thus the tendency of the clay to fracture will
be destroyed, and channels will be formed in the face or grinding portion of the
stone, which channels, as they are in succession brought to the surface by the
wearing away of the stone, will form efficient cutting edges and thus render it
unnecessary at any time to dress the stone. Instead of the pierced pasteboard, I
may use a coarsely woven fabric or a fabric composed of thin strips of cane or wood
connected together by binding threads, such strips being arranged parallel to and
cquidistaut from each other. The bedstone I construct in a manner similar to that
described for the top stone, forming in the eye a Bango to fix the collar bearing for
the spindle of the top stone. In order to permit of the direction of rotation of the
runner being reversed to maintain its efficient cutting action, I prefer to form the
channels in the runner and bedstone with a slight curve from the direction of a
radius line, the curve in the one stone being opposed to that of the other.
When applying the Invention to hulling mills I form, after the manner just
described, not merely rotating discs, but also internal linings for the sides, tops,
and bottoms of the cases, the acting surfaces only, as in the former case, being
channelled.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Gustav Adolph Buchholz in the Great Seal Patent Office on the 21st
July 1879.
IM-
GUSTAV ADOLPH BUCHHOLZ, of Potsdam, in the Empire of Germany, but
temporarily of Chancery Lane, in the County of Middlesex, Engineer.
PROVEMENTS IN THE MANUFACTURE OF FACTITIOUS MILLSTONES AND OTHER
GRINDING OR RUBBING SURFACES."
This Invention relates to the manufacture of an efficient substitute for what are
known as French burrs, and also for the steel blades used in hulling machinery,
In manufacturing, for example, a factitious top or runner millstone according to
this Invention I mould the same in a plastic material which is a preparation of
porcelain or stoneware clay that will, when fired, possess a porous character
throughout. Into this clay, when prepared in the way well known to potters, I
knead small seeds or grain obtained preferably from the siftings of wheat; or I
may use pieces of wood or pasteboard or other combustible material cut into the
required size, and rounded or shaped by a pearl barley mill. By thus kneading up
carbonaceous matter with the clay I obtain, when the plastic material is moulded
and burned, a porous substance admirably suited for the hulling and crushing of
grain, and one which will be cheap to manufacture and need no dressing to maintain
its efficiency.
This composition I mould to form stones, either in one piece or in segments, in
the manner to be presently described.
Supposing a stone to be moulded in one piece, I mix the clay and carbonaceous
matter together in equal proportions by measure, and this mixture I mould in an
open mould similar to that shewn in Sheet I. of the Drawings.
In this Sheet Fig. 1 is a sectional elevation of the mould complete; Fig. 2 shews
the bottom plate in plan view; and Fig. 3 is a cross section of the same; Fig. 4 is
a plan view, and Fig. 5 a cross section of a cylinder which constitutes the periphery
of the mould; Fig. 6 is a vertical section of the core of the mould intended to form
the eye of the millstone. The details of this core will be hereafter referred to.
A is the bottom of the mould, the centre of which is tapped to receive the screwed
end of a taper stud B, upon which stud is placed an inverted cone of cast iron C.
The plate A, which is by preference cast with radial openings for lightness, is
covered by a thin plate of brass to prevent contact of the plastic material with the
iron.
The core is also covered with a sleeve of brass for the same purpose. D is a
cylinder of cast iron forming the periphery of the mould and secured to the plate A
by means of a pair of links, one of which is shewn detached at Fig. 7.
This cylinder D is lined to prevent contact of the clay with iron, and it is fitted
with radial studs, two of which serve to connect the cylinder with the plate by the
links, and two others serve to connect with a crane by which the mould is lifted
and transferred from one place to another. The links are made in two pieces to
facilitate their application, the one half to the plate and the other to the cylinder.
At their junction these pieces are mortised to receive wedges, the driving in of
which will tighten up the links and secure the connection of the plate with the
cylinder.
Figures 8 and 9 shew in plan views the central stud piece and inverted cone;
Figures 10 and 11 shew the brass sleeve in side elevation and plan views. This
sleeve it will be seen is slit longitudinally and its edges are thinned to overlap each
other. It will thus form an elastic lining for the eye of the mill stone, contracting
as the moulded stone contracts in drying, and capable of easy detachment there-
from.
The plastic compound is filled into this mould, and it is left to dry therein until.
sufficiently hard for handling; it is then subjected to pressure in a press of the

page_text: construction hereafter described, and afterwards thoroughly dried preparatory to
being submitted to the heat of the kiln.
Another mode of manufacturing the stone is to build it up in segments and to
compose these segments of the plastic compound before mentioned combined with
sheets of pierced pasteboard or equivalent material that will, like the seeds or pellets
before mentioned, be destroyed by the furnace heat, and thereby ensure by the
formation of vertical channels throughout the mass the production of efficient
cutting edges running radially from the centre of the stone or taking any other
approved direction transversely of the stone.
In forming segment blocks of this character I use the moulding press shewn in
Sheet II., which may be described as a segment shaped mould fitted with a plunger
which is carried by a rocking arm fulcrumed at the centre from which the segment
mould is described.
Having prepared a suitable number of pieces of pierced pasteboard corresponding
in shape to the section of the stone to be manufactured, I coat these pieces on their
opposite sides with the plastic compound and place them edgewise in the mould,
setting them side by side and pressing them by the plunger to ensure the entrance
of the clay into the holes of the pierced pasteboard.
To the pressed slab I add additional pieces of the coated pasteboard until, by the
aid of pressing plunger I form a solid block of the size desired.
I then remove the block from the mould and repeat the operation until a
sufficient number of blocks, say six or eight, are produced for forming the stone.
I then place these blocks together and submit them to pressure to consolidate them
into one annular block, which is then to be dried and subsequently fired in a
porcelain oven; or the segmental blocks may be dried and burned separately, and
then connected together by cement and bound by iron rings.
In Sheet II. Fig. 1 shews the moulding press in plan view; Fig. 2 is a front
elevation; and Fig. 3 is a sectional elevation of the same. A is the segment shaped
mould box fitted with a removable lining of thin sheet brass which extends over a
portion of the button back, and one side of the mould B is a removable segment
piece forming the front of the mould, and held in place by removable pins, as shown
in Fig. 1.
This segment piece is lined or conted with a nonoxidizable metal, and is slotted
to permit of the plunger lever C passing through it. This lever has its fulcrum
at C, and its outer end is connected by a link to a hand lever D, which terminates
in a pawle that takes into a rack of ratchet teeth b formed on the plate B. By
inserting the pawle into these teeth, and pressing forward this lever which has its
fulcrum in the connecting link, it will be caused to carry with it the plunger C,
which will compress the material presented to its action as explained.
When this is effected the lever D is drawn back, and the plunger retiring from
the pressed mass will leave a space for additions to be made thereto, after which
the plunger is to be again advanced to give cohesion to the plastic mass in the
mould, and this is repeated until the block has attained the size desired.
In the Drawing this plunger is shewn as consisting of a flat piece in line with its
lever. When, however, it is required to give the vertical channels in the block a
curved form, or to set them diagonally of the block, the plunger is shaped and
arranged to effect this purpose. Thus the plunger may be inclined on its acting
surface or take a concave or convex forin, and in either case it will compress the
block so as to produce channels therein in form or direction corresponding to the
pressing surface.
The end of the moulding press against which the block is forced inust correspond
to the form and direction of the pressing surface of the plunger.
In Sheet III. I have shown a double moulding press similar in construction to
that just described with reference to Sheet II. This press, however, instead of
lying horizontal is set up vertically, two single presses in fact being arranged back
to back to form the double moulding press.
Fig. 1 is a sido view of the double moulding press; Fig. 2 is a plan view, and

page_text: Fig. 3 is an end elevation of the same; Figures 4 shew the detachable lining in which
the block is moulded, as explained with reference to Sheet II., and by means of
which the block while in a soft state is removed from the mould.
It may be here remarked that instead of employing pierced pasteboard for
forming the vertical channels in the blocks I may use coarse woven material com-
posed of hemp, jute, rushes, or their equivalent, or plaited work of wood, cane, or
their equivalent, the carbonaceous material being sufficiently open to receive the
porcelain mass, and give its walls or layers sufficient connecting strength.
In place of using pieces of pierced pasteboard or reticulated fabrics cut to the
sectional form of the stone, as above explained, I may obtain a like result by
employing a length of woven or plaited fibrous material cut to a width corresponding
to the depth of the stone to be formed.
This fabric I coat on its opposite sides with the plastic compound, and I roll it up
upon a core similar to that shewn in the Drawings, laying coil upon coil until the
required diameter is obtained. The mass thus formed I submit to pressure in a
press, by preference of the construction shewn in Sheet IV. of the Drawings, which
is intended also to operate upon the segment blocks formed in the moulding press,
and compress them into one piece.
This press is shewn in plan view, partly in section, Fig. 1, and in sectional elevation
at Fig. 2. A and A' are the top and bottom plates of the press made of cast iron, and
held apart by means of U shaped flanged blocks B, which are arranged radially,
and at equal distances apart. The lower flanges of these blocks enter recesses cast
in the bottom plate A¹, and the upper flanges receive screw bolts which serve to
connect them with the top plate A.
Fitting into these blocks are horizontally sliding wedges C, which are intended
to move inwards towards the centre of the press, and force before them segment
shaped pressing pieces C', which are made fast thereto by a dovetail or otherwise.
The Drawing shews six of these segment shaped pieces, and the means of pro-
pelling them all simultaneously.
In rear of the sliding wedges C are fitted vertically sliding wedges D, which fit
the shaped blocks and work over guides formed therein. By the depression of
these wedges D the wedges C are forced inwards, and to ensure their being drawn
back on the pressure being removed the wedges D and C are connected by a sliding
dovetail joint.
The bottom plate A' is fitted with a core similar to that described with reference
to Sheet I. of the Drawings, and around this are arranged the moulded blocks
which are to be connected together by pressure.
For the purpose of advancing the pressing piece C', and causing them to compress
tho blocks in one piece, I use an arrangement of chain wheels E, E, for depressing
the wedges D. These wheels are secured to threaded spindles which have their
bearings in the plate A*. These threaded are situate immediately above the
wedges D, and enter respectively into tapped holes formed in those wedges. The
turning of the chain wheels E will depress or raise the wedges D according to
the direction of rotation which they receive. An ondless chain F is passed
around the wheels E, and then brought inwards to lap around a central chain
wheel G, on the axle of which is a hand wheel G₁ for giving rotary motion to the
chain gearing.
The blocks are placed in this press in a partially dried state, or when in a proper
consistency for handling, and care must be taken that the contact surfaces are
sufficiently moist to ensure their adhesion when the blocks are under pressure.
I have given in several Figures details of the construction of this press, a reference
to which will render further description unnecessary. Fig. 3 shows a half plan of
the plate A' detached, and Figures 4, 5, 6, 7, 8, and 9 show the construction of the
wedges C and D and the pressing piece C¹ in connection therewith.
It will now be understood that the stone when moulded in one piece, as explained
with reference to Sheet I., or formed from a coil of coated woven fabric, may receive
the requisite pressure for consolidating it by submitting it to the action of this press,

page_text: which, pressing simultaneously on all parts of its periphery, will ensure the proper
consolidation of the compound mass.
The next operation is to dry the stone. This is effected by submitting it to a
stove heat rising from a temperature of eighty degrees Fahrenheit until two hundred
and twelve degrees has been reached. After this the stone is annealed, during
which process the carbonaceous matter which it contains is converted into
charcoal.
In this state the stone is turned up in a lathe to its required shape, and it is then
submitted to the firing operation, which gives it the requisite hardness for a mill
stone.
In Sheet V. I have shewn at Figures 1 and 2 a mill stone formed according to
this Invention, in plan view and cross section, as mounted upon a backing plate,
which should be tin or copper plated, and a packing of leather, cotton, or pasteboard
should be placed between the stone and the plate. The mill stone may if desired bo
backed by stone or cement, and at Figures 3 and 4 I have shewn a segment block
with vertical channels formed therein.
When preparing cutting surfaces for hulling mills I proceed in the manner
described with reference to the moulding of the segment blocks for the stones, using
the like materials and submitting the moulded blocks to the various operations
already detailed.
Having now set forth the nature of my Invention of "Improvements in the
Manufacture of Factitious Mill Stones and other Grinding or Rubbing Surfaces,"
and explained the manner of carrying the same into effect, I wish it be understood
that under the above in part recited Letters Patent I claim,-
Preparing grinding or rubbing surfaces from porcelain or stone-ware clay rendered
porous in the manner and for the purpose above described.
In witness whereof, I, the said Gustav Adolph Buchholz, have hereunto set my
hand and seal, the Fourteenth day of July, in the year of our Lord
One thousand eight hundred and seventy nine.
חתAr
ΠΠΙΟΠΠΟΙ 17