The morning news. [volume] (Savannah, Ga.) 1887-1900, 1892-02-28
CASTING A BIG GUN.
Details of q Process That Calls for
Much Care and Skill.

MUCH Oar6 ana Skill
From the Boston Post
From o'clock in the morning until 2:3O
o'clock in the afternoon workman sat in a
niche in the rear Of the furnace in the
foundry of the South Boston iron works,
and from time to time he pulled out brick
In the furnace wall and gazed at a mass of
iron which was slowly being fused. Just
% tons Of iron were in the furnace. This
iron in another form was 10 be one of the
new 22-tnch rife mOrtars which are now
being made for the coast defense of the
United States. The Notifications, when
complete, will require more than 500 of
these mortars, of which but 73 are con-
tracted for.
The South Boston iron works has the con.
tract for 43 and the Builders iron foundry
OF providence contract for 80. The
Providence contractors have finished cast
ing, and are now assembling the mortars.
The Boston contractors cast the twenty
fifth mortar yesterday. In the workshops
are the big mortars in every stage of COM
pletion, from the rough casting down to
the nearly completed gun. The cost is
$500 each. OF this the casting cost g., $50,
the steel So, 100. and the assembling $3.50.
This is exclusive of the carriage
E1Ine casting OF the gun 10 an interesting
operation. Capt. A. II. Russell of the
United States ordnance department super
vises the work. In the center of the foundry
is a big pit about is feet deep. which il
lined with brick A day or two previous to
the casting big flask is lowered into the
pit. This flask is in 6 sections of iron aud
is divided once longitudinally and twice
laterally. In this flask, which is perforated
with hundreds Of small holes for the escape
OF the gas, is lining 8 inches thick of
molding sand baked hard. The
inner surface is coated with pow
dered plumbago or facing. At the
bottom of the pit under the center
OF the flask is an iron pot about 10 inches in
diameter, which contains LAYER of sand.
The curvature of the pot is followed in
shape. Exactly In the center of the flask is
placed an arbor of cast-iron, which is
wound with rope covered with fine clay and
baked. This arbor is hollow. The arbor is
huted to allow the gases to escape The
rope Is gradually consumed in the casting.
and it is possible to withdraw the arbor.
leaving the coating Of clay In the interior
to protect the bore of the gun. In the
center Of the arbor is placed an iron pipe,
which extends nearly TO the bottom. Such
is, briefly, the method Of casting.
At 2:30 yesterday afternoon the molten
metal In the furnace was at the proper con-
sistency for casting. Supt. Hunt was in
charge. He cast a financial glance around
and ordered the men to ''let her come"
Two men jammed bars of iron into the top
of the furnace and worked them back and
forth, and the metal flowed forth IN a thin
stream down the troughs Into the ladle and
then to either side Of the flask and dropped
to the bottom. There was a Sizing, snap
ping and suffering of the iron, and as il
disappeared in the mold there
was regular Fourth, OF July dis
play of stars and fireworks. The work
men carefully scraped the Stag from the
metal and regulated the flow, In exactly
nine minutes the mold was full and the big
ladle was placed upright to hold the excess
of iron. Over the end of the arbor was
then placed big tripod. which has a cap
with screw connection for base attach
ments. Then workman approached with
hose and turned stream of cold water
into the arbor. As the water reached the
bottom there was report like a cannon.
and all of the sand and refuse in the arbor
was blown high in the air. The cap was
placed on the tripod and a hose
attached to the pipe on the arbor.
Water at 43' Fair. was turned on and soon
filed the arbor and flowed away in another
pipe. This is the Rodman cold coal~castiug
system. The object is to cool the gun from
the inside and keep the outside as hot as
possible until the bore is cold. This causes
contraction as the layers Of iron cool. each
layer being shrunk on to the other, until the
casting finally Is gradually compressed by
constant pressure from the material com.
posing it.
The wood and coal in the pit is then fired.
and soon the flask is surrounded by a roar,
ing hot fire, which tends to keep the outside
OF the casting in fluid state. The first day
the water flows into the arbor at the rate Of
81 gallons minute. The water
yesterday was S. in temperature when il
first came from the casting. This increased
during the first hour to 79'. The temper
ature is recorded hourly after the
first hour. At 3 O'Clock to-day the arbor
will be removed and water will be allowed
to flow into the bore of the gun. The tenn
perature will then go up to nearly, if not
quite. 2l0'. The fires in the pit will burn
until tomorrow morning, and then the
TASKS will be allowed to cool. From 60 to
50 hours are necessary for casting. The
flask is taken apart, the mold knocked to
pieces, and the rough gun taken out. Dur
ing the first "A hours the cast is watched
carefully. The shrinkage of metal is sun
piled in order that the upper end NAV not
be defective. Draughts of air that would
chill the cast are also guarded against.
When the gun is taken from the Dit il is
carefully examined and then taken to the
machine shop TO be turned and finished
These mortars are hoped with steel rings
and rifed and assembled and sent where
the government may direct, The object of
casting them in the manner described is to
secure gun of great strength. In order
that the metal may thoroughly unite in the
mold and avoid flaws and bubbles the fall of
the molten iron is frequently broken.