Improvements in Millstones.
Year: 1892

page_text: Date of Application, 25th Feb., 1892
Complete Specification Left, 22nd Nov., 1892-Accepted, 31st Dec., 1892
PROVISIONAL SPECIFICATION.
Improvements in Millstones.
We, JOHN HUTTON and ELI DOGGETT of Keeps Wharf, Greenhithe Kent
Millstone Manufacturers do hereby declare the nature of this invention to be as
follows:
This invention relates to the grinding stones used in mills for grinding corn,
cement and other substances, and has for its object a construction of stones which
may be easily adjusted when worn, without necessitating any cutting or chipping
of the stone. In millstones as ordinarily constructed, the upper or runner stone is
provided with an eye or hole in the centre, and the under surface slopes upwards
towards the centre, excepting for a few inches at the outer part, which is horizontal.
A bar is fixed extending across this hole, and a vertical shaft passes through the
centre of the lower or bedstone and is connected to this bar in order to revolve the
stone. This shaft can be adjusted from below in order to lower or raise the runner
stone as required. The substance to be ground is poured through the eye of the
runner stone and fills the cavity between the two stones, coming out at the sides
after grinding. The outer part of the face of the runner stone is rapidly worn
away, while the centre is scarcely acted upon, and consequently the central part has
to be frequently hollowed out as the stone is worn.
According to our invention, the central part of the runner stone is made of metal,
preferably cast steel, the outer edge only being of stone. This central part consists
of three pieces, bolted together and to the stone, the lower part being a thick ring
of steel, with its under surface curved and sloping towards the centre, and provided
with recesses at opposite sides, for retaining the bar above mentioned, the ring
projecting at the back at these points in order to give sufficient depth to the recess.
Radial grooves are provided for guiding the stones etc., to be ground, towards the
periphery, and breaking them up. Four bolt holes are formed in this piece, through
which pass bolts connected to the other pieces. The second piece consists of a ring
with a flange at its lower part, which rests on the back of the piece above described,
the ring extending to the back of the stone, and being provided with a recess to
receive the projecting back of the recess in the first piece. The third part is also
annular and of larger diameter, and is balted by means of lugs to the upper surface
of the stone. Inwardly projecting perforated lugs at the top receive the bolts
connecting the other pieces, and lock-nuts are provided to hold them in position.
The two last pieces may be made of cast iron as there is little wear upon them.
When the outer edge of the stone is worn, the two lower pieces are raised by means
of the bolts & lock nuts, forming the hollowed out part as before, little or no
cutting of the stone being required. The central part of the bedstone is formed of
two thick plates, bolted together and extending to within about a foot of the
periphery. The upper one has grooves corresponding to those in the upper stone,
and a hole of about twelve inches square at the centre. This plate is circular
excepting at two opposite parts, which are made straight, in order to prevent the
revolving motion of the runner stone wearing a groove round the edge. The lower
olate is circular and of smaller diameter and has a square box at the centre
projecting upwards through the hole in the first plate and coming flush with the
op. This box extends downwards for some distance, and serves to support the
bearing through which the shaft for turning the upper stone passes. When

page_text: the stone wears away it is simply raised by ordinary mechanism to the level of
the plates:
Dated this 22nd day of February 1892.
GEO. H. RAYNER,
37, Chancery Lane, London, W.C., Agent for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Millstones.
We, JOHN HUTTON and ELI DOGGETT, of Keeps Wharf, Greenhithe, Kent,
Millstone Manufacturers, do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :—
This invention relates to the grinding stones used in mills for grinding corn,
cement and other substances, and has for its object a construction of stones which
may be easily adjusted when worn without necessitating cutting or chipping of the
stone.
In millstones as ordinarily constructed the upper or runner stone is provided with
an eye or hole in the centre, and the under surface slopes upwards towards the
centre, excepting for a few inches at the outer part, which is horizontal. A bar ist
fixed extending, across this hole, and a vertical shaft passes through the centre of
the lower or bedstones, and is connected to this bar in order to revolve the stone.
This shaft can be adjusted from below, in order to lower or raise the runner stone
as required. The substance to be ground is poured through the eye of the
runner stone and fills the cavity between the two stones, coming out at the sides
after grinding. The outer part of the face of the runner stone is rapidly worn
away, while the centre is scarcely acted upon, and consequently the central part
has to be frequently bollowed out as the stone is worn. According to our invention,
the central part of the runner stone is made of metal, preferably cast steel, the outer
edge only being of stone.
This central part consists of three main pieces, two which are rigidly connected
together, the lower one consisting of a thick ring of steel, its under surface
sloping, upwards towards the centre, and furnished with grooves forming
continuations of the ordinary grooves in the stone provided for the purpose of
guiding the material to be ground, to the edge of the stones. This ring is fixed to
the flange of an annular part extending vertically from it to the top of the stone,
and may if desired be made in one piece with it.
The bar used in revolving the stone is retained in recesses formed in this
annular part. These rings are attached to an upper part, bolted or otherwise
fixed to the top of the stone by means of. a number of screwed bolts with nuts at
the top: These bolts pass through a flange or lug belonging to the fixed part, and
the arrangement is such that as the stone gets worn away the lower parts are
drawn up by means of the bolts & nuts to the required height, the stone requiring
little or no cutting excepting at the grooves.
The central part of the bedstone is formed of two plates bolted together, the
upper one having grooves corresponding to those in the upper stone, and a hole at
the centre, through which a box belonging to the lower plate projects, the top
coming.flush with the upper-plate. This box serves as a bearing for the shaft
revolving the upper-stone; brasses and lubricating holes being employed.
As the stone gets worn away it is raised by means of screws from the ground or
a bed plate, the latter also serving to support the central plates by a number of
vertical arms or pillars:
The stones are constructed of a number of sections fitting together and preferably
cut straight or with slightly inclined surfaces at their inner edge forming polygonal
holes, in order to prevent the central. plates slipping: The upper part of the

page_text: runner stone and the bottom of the bedstone are formed preferably of concrete or
cement reducing the amount of stone required.
In order that the invention may be more clearly understood, reference is had to
the accompanying sheets of illustrative drawings, in which
Fig. 1. is a vertical section of the stones in position,
Fig. 2 a plan of the runner or upper-stone, and
Fig. 3, a plan of the bedstone.
A, A, are the sections forming the runner stone, furnished with the required
number of grooves a, for leading the substances to be ground to the periphery of
the stone. These sections are firmly connected together by the bands A' around
their periphery. A layer of concrete B. forms the upper part of the stone, and
serves to support the ring or lining C. which is also secured to the stone sections A
by the lugs and bolts c'. The inner annular box D is supported from lugs C'
on the lining C by means of bolts E, screwed for the whole or the greater part of
their length and adjusted by nuts e, fixed at the bottom in the flanged by
screwing or other means. The face plate F is rigidly attached to the flange d and
is furnished with grooves, forming continuations of the grooves a.
C
The cross
bar G for revolving the stone is supported in a box g, forming part of the metal
frame. The lower or bed stone is also formed of a number of stones H, which
may be of shapes similar to those forming the runner stone, connected together
by the bands ', and provided with grooves on top. The lower part of this
stone is preferably formed of a layer of concrete, or cement.
The central part is formed of a large plate K having a box k at the centre
forming a bearing for the shaft driving the runner stone. On this and fixed to it
is placed a face plate L having a hole at the centre to allow the top of the box k to
pass through and grooves opening into grooves h.
The plate K. is supported by the arms or pillars M, fixed on the bed plate N,
which also serves to carry the screws n by means of which the stone is raised to
its proper level as it is worn away.
Having now particularly described and ascertained the nature of my said inveu-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1. A mill stone, having a large central hole in which a metal frame is placed,
consisting of an annular face plate and a fixed supporting frame with screws to
adjust the stone or face plate in such a manner that they will be kept in proper
relative position, substantially as described.
2. In a mill stone the combination with a ring or lining C. fixed in the eye or
hole of the stone of a second ring D, carrying the annular face plate F and
attached to the first by a number of bolts E with nuts, in such a manner that the
face plate can be drawn towards the fixed ring as the outer stone gets worn,
substantially as described.
3. In a stationary mill stone, the combination with a face plate L of a plate K
with box k serving as a bearing for the driving shaft, and mechanism for raising
the stone up to its proper level as it gets worn away, the plates remaining
stationary.
4. The improved runner and bed-stone, constructed substantially in the manner
described, and illustrated in the accompanying drawings and for the purposes
specified.
1
1 1
2 X7
1000
GEO. H. RAYNER,
37, Chancery Lane, London, W.C., Agent for the Applicant.