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172                                FOUNDRY  WORK
Shop Arrangements and Organization
Only one design of foundry is regarded with favour now, a rectangular
building, parallel, with unobstructed roof light, and comprising one bay, or
more often two or three, each bay with its own roof, but without obstructions
in the shape of separating walls.   A clear area is thus included between the
'                           outer walls that permits of ready intercommunication and efficient super-
!                          vision.    Within these bays, the work of different departments is carried on
in strictly localized areas, each being served with the cranes and tackle that
s                          are specially adapted for the work to be done.    These departments in the
I                          majority of foundries include heavy green sand, light green sand, plate and
f                          machine moulding, often subdivided further, to locate castings made in
quantities by themselves, loam moulding, and core making. These classes
of work are done by separate groups of men who seldom handle any other
branch, having developed the faculties of experts. In addition, the melting
of metal is the exclusive task of the furnaceman and his helpers; sand grinding
and mixing occupy other hands; fettling is done in a separate room. Crane
operators are required, and there is a large proportion of loading, carrying,
and attendance on the moulders that engages the services of a body of
j                          unskilled labourers.
I                               Roof spans may range from 30 to 40 ft., depending on the bulk of the
j                          work done.   A height of about 25 ft. to the spring of the roof is suitable.
If symmetry is desired, spans should be equal and heights uniform, so that
future longitudinal extensions are simplified. The enclosing walls should
be of brick. The internal roof columns may be either of cast iron or built
up of steel bars and rolled sections. In each case attachments can be made
to receive the pintles of swinging jib cranes. The main section usually
terminates with the runways for the overhead cranes, and a separate smaller
section is carried up to the roof principals. A ridge roof is usual, with a
ventilating louvre -surmounting. The principals are of steel, formed of tee
sections and bars. It should be covered with slates, laid on felt, spread on
f                         boards. Illumination is provided by a continuous skylight along each
I                         ridge, or along the north ridge only.   An alternative is the saw-tooth roof,
j                         with north light, but this is not nearly so common as the symmetrical design.
j                         Puttyless glazing should be used, and a thick glass.   Windows are not
I                         necessary in the brick walls, but they relieve the otherwise depressing effect.
J                         As in most cases, the cupolas and the machines, together with the sand and
I                         coke stores, are located outside and close to the main building.   This pre-
!                         eludes the employment of windows there, but they can be inserted in the
f                         opposite side and in the end walls.
I                              The minute subdivision of tasks that is familiar in the big machine shop
i                         does not exist in the foundries.   Men are occupied in one or other of the
*                         leading sections previously mentioned, beyond which they seldom go.   But