Millstone Page: 3 of 4
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UNITED STATESPATENT OFFICE.
JOHN L. DURHAM, OF SANCO, TEXAS.
MILLSTONE.Specification of Letters Patent.
Patented June 16, 1908.
Application filed December 4, 1905. Serial No. 290,261.
To all whom it may concern:
Be it known that I, JOHN L. DURHAM, a
citizen of the United States, residing at
Sanco, in the county of Coke and State of
5 Texas, have invented new and useful Im-
provements in Millstones, of which the fol-
lowing is a specification.
This invention relates to millstones; and it
has for its object to provide an improved
10 millstone dress which shall be conducive to
the best results in assuring a thorough grind-
ing of the grain; in securing a uniform grade
of product; and in increasing the capacity of
the stones for work.
15 With these and other ends in view which
shall readily appear as the nature of the in-
vention is better understood, the same con-
sists in the improved millstone dress which
will be hereinafter fully described and par-
20 ticularly pointed out in the claims.
In the accompanying drawings, Figure 1 is
a plan view.of a portion of the upper stone
dressed in accordance with the invention;
only that portion of the stone being shown
25 which is closely adjacent to the eye, the
stone being shown in inverted position so as
to expose the working face. Fig. 2 is a sec-
tional view taken on the plane indicated by
the line 2-2 in Fig. 1, and the stone being
30 shown in inverted position. Fig. 3 is a sec-
tional view taken on the plane indicated by
the line 3-3 in Fig. 1. Fig. 4 is a sectional
view taken on the plane indicated by the line
4-4 in Fig. 1. Fig. 5 isa .plan of a bed
35 stone dressed in accordance with the inven-
tion. Fig. 6 is a vertical sectional view
showing the bed stone and the upper stone
assembled in running position.
Corresponding parts in the several figures
40 are denoted by like characters of reference.
The two millstones which are designated
as the upper stone 1 and the bed stone 1' are
dressed precisely alike, and the description
of one will apply to both. Each of the
45 stones is provided with an annular groove or
channel 4 which, in the upper stone is formed
immediately adjacent to the eye 2; the said
groove or channel being formed in a corre-
sponding location in the lower stone, as will
5o be clearly seen by reference to Fig. 6.
In accordance with the invention there is
formed in the working face of each stone a
plurality of feed ducts 5, preferably tangen-
tial to the annular groove or channel 4, and
55 comprising grooves or channels that are ap-
proximately V-shaped in cross-section, asI best seen in Fig. 3. These grooves, which
constitute the feed grooves, are of an extreme
length approximately equal to, but not ex-
ceeding the diameter of the eye, and said 60
grooves are at their inner ends of an extreme
depth which is less than that of the annular
groove or channel 4, while at their outer ex-
tremities they merge with the face of the
stone; the bottoms 6 of said grooves being 65
inclined and dying or shallowing into the
general plane of the grinding surface, as will
be clearly seen in Fig. 4. The edges or walls,
7, of the grooves or ducts 5 are formed at ap-
proximately right angles to the working face 70
of the stone while, owing to the cross-sec-
tional V-shape of said ducts their rear edges
merge with the face of the stone; said rear
edges being preferably rearwardly concaved
as will be seen at 8, so that the bottoms of 75
the ducts will merge very gradually into the
working face of the stone. These ducts in
connection with the annular channels 4 con-
stitute the entire millstone dress; and the
usual feed ducts which extend nearly or quite 80
to the peripheral edges of millstones as ordi-
narily dressed, are entirely omitted.
When the stones, dressed in accordance
with the invention, are assembled, as shown
in Fig. 6, grain fed through the eye of the 85
stone will pass into the space formed by the
annular channels 4, said space constituting
a receptacle from which the grain, by the
centrifugal action set up by the rotation of
one of the stones, is discharged between the 90
working faces of the stones, being subjected
to a gradual reduction process between the
bottoms 6 of said feed ducts which, as stated,
merge with the working faces of the stones.
The ducts 5 being of an extreme length which 95
is only approximately equal to but not ex-
ceeding the diameter of the eye, and the
latter, which is selected as a unit of meas-
ure for the purpose of establishing the pro-
portionate dimensions of the ducts with re- 100
nation to the stones being usually of a diam-
eter not exceeding one-twelfth of the total
diameter of the stone, it follows that a rela-
tively very small or minimum proportion of
the entire working faces each of which lies in 105
one general plane, of the stones is furrowed
by these ducts, or leading furrows, and that
the grain, after preliminary reduction by the
shearing action between the inclined bottoms
of the ducts on the opposing faces, will be 110
immediately subjected to the action of the
extended working faces,, which occupy aNo. 891,050.
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Durham, John L. Millstone, patent, June 16, 1908; [Washington D.C.]. (https://texashistory.unt.edu/ark:/67531/metapth511800/m1/3/?q=%22%22~1: accessed June 21, 2024), University of North Texas Libraries, The Portal to Texas History, https://texashistory.unt.edu.; crediting UNT Libraries Government Documents Department.