The Rock Island Argus. (Rock Island, Ill.) 1877-1885, 1884-02-05
Diamonds for Drills.


Diamonds are comparatively cheap
nowadays" q rock drill manufacturer
said, land the diamond bit sets used in
the diamond drills do not cost as much
as they did, -
s'Are genuine diamonds used in these
drills, or are they chaffed diamond drills
because the steel has an extremely hard
temperp" the reporter asked.
Diamonds are used in the drills.
They are chiefly one and two caret
stones. At present they cost about
twenty dollars a caret. They are in the
rough. The diamond-set bit is hollow.
1t is steel thimble, having three rows
of diamonds embedded in it, SO that the
edges of those in one row project from
its face. while the edges of those in the
other two rows project from the inner
periphery respectively. The diamonds
of the first mentioned row cut the path
of the drill in its forward progress,
while those of the outer and inner
periphery of the tool enlarge the
cavity" ..s. f.
'sHow are the diamonds set in the
bitp"
The bit is of soft steel, in which holes
are drilled. After the diamonds are
fitted the metal is hammered against
them so that they remain firm.
do the diamonds wear out, ~
Their edges which come in contact
with the rock get little smooth. and
they are taken out and reset, so that q
fresh edge is presented.'
Have all the hollow drills three rows
of diamonds?' r..
mo. Some have only one row, but
these are not very large. The diamonds
stand out from the steel setting, so that
the steel does not come in contact with
the rock"
How are the diamond drills
worked?'' e
by rapid rotation varying any
where from four hundred to one thous-
and revolutions a minute, There are
different machines used for different
kinds of drilling, For deep boring Q
a machine with double oscAlating cyl
inder engine is used, mounted on an up
right or horizontal tubular boiler The
machine has a screw shaft made o.
heavy hydraulic tubing from five tC
seven feet in length, with deep screw
cut in the outside. The shaft also car
ries a spline, by which it is feathered t.
the lower sleeve gear This gear il
double. and connects by its upper teeth
with beyeled driving gear, and by it
lower teeth with release gear, which
is friction gear, and is fitted
to the lower end of the shaft, to the
top Of which gear is feathered, fitting
to the upper gear on the screw shaft
which has one or more teeth less thai
| the upper gear on the feed shaft, where
by differential feed is produced. Thi
friction gear is attached to the bottom
of the feed shaft by a friction nut, pro
ducing o combined differentialsan and fric
tional feed, which renders the drill per
fectly sensitive to the character of th,
work through which it is passing, an,
maintaining uniform pressure. Th
drill rod. made OF heavy lap-weld tub
ing, passes through the screw shaft an,
is held firm by a chuck at the bottom O
the screw shaft To the lower end O
this tubular boring rod the bit is screwed
and to the upper end is watch swivel
to which connection is made with
steam pump You can see by this tina
the machine is very simple and nc
. likely to get out of order.'
The reporter fell into chair. Whe
he came to, the drill man was saying;
, sThe screw shaft, being rotated an
fed forward, rotates the drill rod an
bit, cutting an annular channel"
Where do you get the diamonds fc
the bits?" the reporter asked in despel
alton. sNa
They come principally from Brazi
Some come from Siberia and some froI
q the South of Africa; the latter, how
n ever, are more CLASSY and are not E
y tough as the Brazilian diamonds, an
= are much more likely to crush undo
pressure. N T. Sun.