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Full text of "Modern Mechanical Engineering Vol-I"

164

FOUNDRY WORK

independent of its pattern, which
is laid on the face of the board.
To this the bottom box or drag
is pinned before ramming. The
time otherwise occupied in making
a temporary sand bed on which to
ram the drag (to be afterwards
thrown away) is saved, and the
board provides a true joint plane
without strickling and sleeking it
with the trowel. From this to the
permanent mounting of a pattern
or a portion of a pattern or more
than one pattern on a plate of
wood (fig. 66) or of iron (figs. 67
and 68), where pattern portions
are attached on opposite sides of
the same plate, is a natural de-
velopment, as is also their trans-
ference from the floor or the work
bench to the table of a machine.
Economies do not cease here, but
they increase when joints are of
non - plane shapes, combining
slopes and curves, and when several patterns are mounted on one

plate, each requiring a separate
runner. In these cases it is
usually preferable to cast pat-
tern parts, plate, and runners
all in one piece, than to adopt
the method common with
plane plates of preparing the
patterns separately, and at-
taching them to their plates
with screws or rivets.

Obviously, the moulding
table is the first important
element in any machine, since
it is the plate to which the
pattern parts are attached
directly, or to which the
patterns, already mounted on
their plates, are secured.
Tables either turn over, to

Fig. 69.~-Turn-over Table Machine, with presser head above t^ing each faCC Uppermost
and carrying-off table that runs on tracks below. Pattern parts /£/*« Ar\ «mr1 nr\\ nr thp»v sir A
are mounted on plate attached to the table.                                  Vn5s- °9 ano 7% or mey drc

Fig. 68.—Brake Blocks mounted on Plate