The Roanoke times. [volume] (Roanoke, Va.) 1890-1895, 1892-02-13
DRILLING TINY HOLES.

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a hole Ill 600 of IN inch in diameter can
he drilled through diamond, sap
phlre, or n ruby. Formerly tiny holes
plke that were drilled by hand, but
now q machine that John Wennstrom
has perfected which makes 81, 600 revo-
dutlonsln minute, can pierce n sapphire
one-sixteenth of an inch in thickness
ln'ten minutes. A hole 1900 of IN inch
IN diameter has been considered re-
markable, bnt nowadays jewels with
holes much smaller in diameter ure re-
CURED for several purposes. They are
inserted in plates for drawing wire and
hoer, and are used in electrical, mathc-
NAUTICAL, and nautical instruments.
Thomas A. Edison had several plates
made for drawing platinum wire 1-1,00
to "-1, 00U of IN inch in diameter Or
binary fine wire is drawn through steel
plates. but if steel were used for minute
work 1T would be worn away too much
and would cause an enlargement of the
wire. Therefore diamonds, sapphres,
and rubies are used when the minutest
holes are needed and when it is neces-
sary to have wire of the same thick
ness throughout its length, the wear on
jewels being hardly perceptible. Sap
phires and rubies are next to diamonds
in durability. Agatcs are too soft.
>. For many years the Jcnots. husband
and wife, were the only borcrs OF Jewels
in this country. They came from
France about twenty five years ago
and, settling here supplied the trade
with pierced jewels. The husband
taught his wife the secrets of the art,
and when he died Mime. Jenot con-
tinucd in the business. She died u few
years ago. Her Jewels were pierced by
hand. and she was never able to pierce
a jewel for draw plate with II hole less
than 900 of an inch in diameter.
The process of boring by hand was
costly and laborons, and the holes
were frequently crooked. iIut the
Jcnots had plenty tn do, because they
were the only borcrs in this country
who could compete with French borers.
draw plate with a hole IL, 600 of an
inch in diameter costs now $40, and one
with hole 4-l.000 of an inch can be
bought for $3.50. In drawing very fine
: Wire several plates nre used, all wires
below 81, 600 of an inch requiring inter
mediate plates owing to the lack of
tensile strength. Platinum is used for
the smallest wire that can be drawn.
The cross web in fine microscopes is Of
platinum.
The development Of the science of
electricity has created n demand for
very fine wires The platinum wires
in incandcscent lamps are drawn
through sapphire plates, and the very
finest platinum wires are used in many
dn tn nd al.
ments Torpedo magnets and electrical
meters require very fine wires. Thirty
six miles of insulated wire used by the
government in experiments with tor
pedoes measured only about five inches
in length by three in diameter when
wound on spool. The fiber used as
carbon filaments in incandescent lamps
is scrapcd to an even thinness by being
drawn through sapphire plates from So
1000 to 4-1,0o0 Of an inch in diameter.
Fiber that has been drawn through
steel plates has not the smooth finish
of fiber from sapphire plates. Brass
wire for brushes used by silversmiths
and jewellers can be drawn to $1,000
of an inch--the diameter of hair The
holes in watch jewels are from $1,000
to 12-1 900 of an inch.
BY the old method of boring. the drill
was fixed and the jewel, EN- bedded in a
holder, was pressed and revolved
against it. In Wcnnstroms machine
the drill revolves and the jewel is fixed
on a bed-platc A hole of the REQUIRED
size is bored straight through and then
the openings are smoothed. For holes
$1,000 of an inch and larger the points
of the drills have diamond cutters, but
for the smallest holes the drills are of
soft iron into which particles of dia-
snond dust become embedded as the
drills pierce the Jewels. BY an auto.
matte appliance Il drill is raised and
lowered ut intervals to allow the dia-
mond dust to collect under the point Of
the drill. Diamond dust, which has the
appearance oi gray mud, is made by
pulvcrizing chips in an iron mortar and
grinding the PARTICLES with an agate
mortar and pestle to various degrees of
fneness. The dust, mixed with oil. is
applied to the points of the drills with
camel's-hai, brushes. After the Jewels
have been pierced they are embedded
in brass holdcrs for the openings in the
draw plates For some purposes q
pierced Jewel is cut into halves, and
each half is then mounted in hinged
holder that can be opened and shut
like a knife. Instead of sticking
the end Of a length of fiber
through the hole, which is sometimes
adelicatc operation. the holder is opened
and the fiber placed in one of the grooves
Of the split jewel After a jewel has
been pierced, wires of different sizes are
inserted in the hole until one fits per-
feotlY, and then the diameter of the