IMPROVEMENTS IN THE CONSTRUCTION OF GRINDING MILLS
Year: 1874

page_text: LETTERS PATENT to Bristow Hunt, of Serle Street, Lincoln's Inn, in
in the County of Middlesex, Gentleman, for the Invention of
"IMPROVEMENTS IN THE CONSTRUCTION OF GRINDING MILLS." -A communi-
cation from abroad by The Enterprise Manufacturing Company,
T
1 O
PROVISIONAL SPECIFICATION left by the said Bristow Hunt at the
Office of the Commissioners of Patents, with his Petition, on the
18th February 1874.
I, BRISTOW HUNT, of Serle Street, Lincoln's Inn, in the County of
Middlesex, Gentleman, do hereby declare the nature of the said Inven-
tion for "IMPROVEMENTS IN THE CONSTRUCTION OF GRINDING MILLS," (a com-
munication to me from abroad by The Enterprise Manufacturing
Company, of Philadelphia, Pennsylvania, in the United States of
America), to be as follows:-
-

page_text: Secondly. To securely retain the working parts of the mill within the
casing without interfering with their ready removal when necessary.
Thirdly. To prevent waste of the material to be ground in its passage
from the hopper to the space between the burr and shell.
Fourthly. To facilitate the adjustment of the grinding surfaces of the
mill for coarse and fine grinding.
And, Fifthly. To insure the proper durability of the burr.
These objects are attained by constructing the mill as follows:-The
outer casing of the mill consists of two semicircular parts which meet at
a horizontal line drawn through the centre of the mill spindle, on which
line also is the centre pin of a hinge connecting together the two halves
of the casing, the latter being further secured at a point opposite the
hinge by a bolt connected to lugs on the lower portion of the casing and
having a thumb nut bearing on a slotted lug on the upper portion of the
casing so that the latter after looseing the nut and depressing the bolt
can be turned outwards and downwards, thereby exposing the interior
works of the mill and permitting their removal from the casing.
The hopper is secured to the upper half of the casing, and the lower
portion of the latter is attached to the base which contains the drawer
for receiving the ground material.
The mill spindle has its bearings partly in the upper and partly in the
lower portions of the casing, and the coffee or other material is ground
by causing it to pass from the hopper between a rotating burr keyed to
the spindle and a fixed shell through which the spindle passes, but
which is rigidly confined between the two halves of the casing in the
following manner:-A hollow conical portion of the shell has a disk-
like flange, on the edges of which are six lugs, two of which when the
spindle is placed in position upon the lower section of the casing enter
recesses formed for their reception in the latter, the exact position of the
shell being thus determined before the upper section of the casing is
closed upon the same. In thus adapting the two lugs of the shell to the
said recesses two other of the lugs are also fitted to slotted lugs formed
in the lower half of the casing, and similar slotted lugs on the upper
half of the casing adapt themselves to the remaining two lugs of the
shell when the said upper half is closed upon the lower, thus rigidly
confining the shell and permitting the burr secured to the spindle to be
and adjusted from and towards the same for coarse and fine grinding, as

page_text: hereafter described, while by simply separating the two halves of the
casing both burr and shell and the spindle can be lifted out of the mill
and ready access will thus be obtained to all parts of the latter for the
purposes of cleansing or repairs. An opening is formed in the upper
portion of the shell, and a partition and shoot cast within the upper half
of the casing fits snugly over this opening and against the above
mentioned disk-like flange when the mill is closed and forms a com-
munication between the said opening and the hopper, and thus directs
the whole of the materials to be ground into the space between the burr
and shell.
In the present instance the shaft is furnished with two fly wheels, one
at each end, but in mills of a smaller class the shaft is furnished at one
end only with an ordinary handle. A set screw passes through one fly
wheel or handle and bears against a collar loose on the shaft and having
a projection for receiving the end of the screw so that the said collar
will revolve with the shaft and wheel; a spiral spring intervenes between
the mill casing and the other fly wheel, or between the said casing and a
collar on the shaft if the wheel is dispensed with. A simple turn of a
regulating screw will cause the said spring to move the shaft in the
required direction so as to draw the burr away from the shell, and on
turning the screw in the opposite direction the burr will be drawn
towards the shell and the mill will thus be adjusted for fine grinding.
In ordinary mills the devices or arrangements for regulating the grind-
ing surfaces are either difficult of access or are not readily understood
by those who have to make the adjustments, whereas in this improve-
ment the adjusting screw is in an exposed position and any one can soon
ascertain that by turning the screw in one direction the burr will be
brought closer to the shell, and that by turning it in the opposite
direction the burr will be moved away from the shell by the spring.
It is essential that the burr in order to insure proper durability should
be made of metal so hard that it can not be bored out to fit the shaft
knee, it is made in two parts, namely, the disk of metal soft enough to
be bored, and the hard grinding portion in which holes are cast for
receiving the screws or rivets by which the two parts are secured
together.

page_text: LAVN m pursuance of the comuITIONS VI
filed by the said Bristow Hunt in the Great Seal Patent Office on
the 18th August 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, BRISTOW
HUNT, of Serle Street, Lincoln's Inn, in the County of Middlesex,
Gentleman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent bearing date the Eighteenth day of February, in the year of
our Lord One thousand eight hundred and seventy-four, in the thirty-
seventh year
of Her reign, did, for Herself, Her heirs, and successors,
give and grant unto me, the said Bristow Hunt, Her special licence that
I, the said Bristow Hunt, my executors, administrators, and assigns,
or such others as I, the said Bristow Hunt, my executors, admini-
strators, 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 THE CON-
STRUCTION OF GRINDING MILLS," (a communication to me from abroad by
The Enterprise Manufacturing Company, of Philadelphia, Pennsylvania,
in the United States of America), upon the condition (amongst others)
that I, the said Bristow Hunt, my executors or administrators, 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 Bristow Hunt, do hereby declare
the nature of the 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, and on reference being had to the
accompanying Sheet of Drawings, that is to say :-
The objects of this Invention arc,—

page_text: The spindle D has its bearings partly in the upper and partly in the
lower portion of the casing, and the coffee or other material is ground
by causing it to pass from the hopper between a rotating burr F keyed
to the spindle and a fixed shell G through which the spindle passes, but
which is rigidly confined between the two halves of the casing in the
following manner :-A hollow conical portion % of the shell G has a disk-
like flange k', on the edges of which are six lugs p, p, q, q, and r, r, the
two latter of which when the spindle is placed in position upon the lower
section of the casing enter recesses », s, formed for their reception in the
latter, the exact position of the shell being thus determined before
the upper section of the casing is closed upon the same. In thus adapting
the lugs to the recesses & the lugs q, q, are also fitted to slotted lugs t, t,
formed in the lower half of the casing, and similar slotted lugs u, u, on
the upper half of the casing adapt themselves to the remaining lugs p, p,
when the said upper half is closed upon the lower, as shewn in Figure 3,
thus rigidly confining the shell G and permitting the burr F secured to
the spindle to be adjusted from and towards the same for coarse and
fine grinding, as hereafter described; while by simply separating the
two halves of the casing both burr and shell and the spindle can be
lifted out of the mill, and ready access will thus be obtained to all parts
of the latter for the purposes of cleansing or repairs. An opening v is
formed in the upper portion of the shell, and a partition or shoot w cast
within the upper half of the casing fits snugly over this opening and
against the above-mentioned flange k¹, when the mill is closed and forms
a communication between the said opening and the hopper e, and thus
directs the whole of the material to be ground into the space between
the burr and shell.
In the case illustrated the shaft D is furnished with two fly wheels H
and H', one at each end, but in mills of a smaller class the shaft is
furnished at one end only with an ordinary handle. A set screw c passes
through the fly wheel H or handle and bears against a collar g loose on
the shaft and having a projection for receiving the end of the screw (see
Figure 5), so that the said collar will revolve with the shaft and wheel.
A spiral spring intervenes between the mill casing and the other fly
wheel H (or between the said casing and a collar on the shaft, if the
wheel is dispensed with), and tends to draw the said shaft in the direction
of the arrow, Figure 2. A simple turn of the screw in one direction c
causes the spring / to move the shaft in the direction of the arrow

page_text: and to draw the burr away from the shell, and a turn thereof in the
opposite direction causes the burr to be drawn towards the shell and
adjust the mill for fine grinding.
In ordinary mills the devices or arrangements for regulating the
grinding surfaces are either difficult of access or are not readily under-
stood by those who have to make the adjustments, whereas in or
according to this improvement the adjusting screw c is in an exposed
position, and any one will soon perceive that by turning the screw in
one direction the burr will be brought closer to the shell, and that by
turning it in the opposite direction it will be moved away 'therefrom by
the said spring h.
It is essential that the burr in order to insure proper durability should
be made of metal so hard that it cannot be bored out to fit the shaft,
hence it is made in two parts, namely, the disk i of metal soft enough
to be bored, and the hard grinding portion in which holes arc cast for
receiving the screws or rivets by which the two parts and secured
together, scc Figure 6.
Having now particularly described and ascertained the nature and
objects of the said Invention, together with the manner in which the
same is to be or may be performed or carried into practical effect, I
would remark in conclusion that I claim as the Invention communicated
to me by the said Enterprise Manufacturing Company,—
Firstly. A grinding mill in which are combined a burr secured to and
rotating with the spindle, and a fixed shell contained within and held
by and between two parts of a casing.
Secondly. The combination of the shell G and its lugs with the slotted
lugs and recesses in the upper and lower sections of the casing, between
which the said shell is retained.
Thirdly. The combination of the flange k¹ of the shell with the
partition to cast in the upper portion A of the casing, and forming with
the flange a shoot.
Fourthly. The shaft D carrying the burr F and owing its longitudinal
position in its bearings to the spring h, collar g, and set screw c.
And, Fifthly. The within described burr consisting of the soft metal
disk i secured to the shaft, and the hard metal grinding portion
secured to the said disk; all substantially as herein-before described,

page_text: and as illustrated on the accompanying Drawings, and for the purposes
respectively specified.
In witness whereof, I, the said Bristow Hunt, have hereunto set my
my hand and seal, this Seventeenth day of August, in the year
of our Lord One thousand eight hundred and seventy-four.