Green-Mountain freeman. [volume] (Montpelier, Vt.) 1844-1884, 1883-11-28

DRILLING STONE WITH DIAMONDS
"Damouds are comparatively cheap now
adays," a rock drill manufacturer said
"and the diamond set bits used in The
diamond drills do not cost as much as
they did"
Are genuine diamonds used in these
drill, OF are they called diamond drills
because the steel has an extremely hard
temper?' the reporter asked.
"Diamonds are used in the drills. They
are chiefly ono and two carat atoues. Al
present they cost about $50 Il carat. They
arc in the rough. The diam mond-set bit is
hollow. 1t is Il steel thimhle, having
three rows Of diamonds embedded in it,
so that the edges Of those in one row pro-
iect from its face, while the edges of those
in The other two rows project from the
outer and inner periphery respectively.
The diamonds Of the illst-mentioned row
cut the path Of the dgill in its forward
progress. while hose on the outer and
inner pofiphary Of IL" tool cnIalge the
cavity
GLOW are the diamonds set in the bit?"
1.-THE bit is of sof. 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 q little smooth, and
they are taken out and lcsat, &c That q
fresh edge is presented"
Have all the hollow drills three rows
of diamonds"
"No. 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 tho diamond drills worked?'
"B7 rapid rotation, varying anywhere
from 400 to 1900 revolutions a minute.
There are different machines used for diff
ferent kinds Of drilling. For deep boring
q machine with double oscillating cylin-
der engine is used, mounted on an up
right or horizontal tubular boiler. The
machine has a screw shaft made of heavy
hydrauio tubing from five TO seven feet
in length, with a deor screw nut in the
outside. The shGf also carries 81 spine,
by which it is fca heret the lower sleeve
gear. This gear Is uouho, and connects
by its upper teeth with beveled driving
g r, and by its lower teeth with + release
gear, which is 4 friction gear, and is fitted
10 the lower end of the feed shaft, to the
top Of which D go4r ia f2a!4cred, fitting
to the upper gear On the zal3W shaft,
which has one OF more tech less than
the uppe. ga2r On the feed -3a.t, whereby
a difIerantial feed Is produc25. Thig fric-
ton gear is attached to the bottom Of the
feed shaft by q friction nut producing a
combined diiie-0ntiai and lgicttonal feed,
which renders the drill perfectly sensitive
to the character OF the work through which
it is passing, and maintaining q uniform
pressure. The drill rod, made of heavy
lap weld tubing, passes through the screw
shaft and Is held firm by chuck at the
bottom Of the screw SHAFT, 70 ihe lower
end of this tubular boring rod the bit is
screwed, and to the upper end is watch
swivel, to which correction Is made with
e steam pump. Lo1 can gCo by this that
the machine is very c,olnla md rot likely
TO gel out OF O. Der"
The reporter l.ll i4l. . nul&. When
he came 10 the drill. mn 7as saying:
sThe screw shat. being rotated and fed
forward, rotate9 the drill I'D pna cit, cut
ting an angular chsnne,-"
"WheYe 10 v0n ret to9 diamonds for
the bits" tho reporter asked in despera-
ton.
"Tnog come principally from Brazil.
Some come from Siberia and some from
the south of Africa the latter, however,
are more CLASSY and arc oot SO tough as
the Brazilian diamonds. and are much
&C.. :