Modern Mechanical Engineering Vol-I

EXAMPLES OF WORK

97

to a separate plate. This enables two men or sets "of men to be working on
the same mould, one on copes, the other on drags, a very great economy,
which is necessary when a large output is required.

Metal Plates and Patterns.
—These are necessary for the
highest production, not only for
machine-moulding, with which
they are chiefly associated, but
also in the hand-moulding of
the smaller articles required in
large numbers. Patterns are
mounted on opposite sides of
an iron plate (fig. 78), or on one
side of separate plates. Weight
is kept down by making the
plates thin, say from f in. to
% in., and by lightening the in-
teriors of the patterns, though
these provisions are of less
moment when work is moulded
by machine than when done by
hand. Great care is necessary
when fitting the pattern parts to
their plates. Holes are drilled
through both in place, and these
receive dowel-pins or screws.

In SOme Cases a portion Of a Fig. 78.—Iron Cock Pattern mounted on an Iron Plate

pattern may go right through a

plate. All this work is rather of a special character, since patterns have

to be finished in the lathe, the grinder, and with files and scrapes.

In a good many instances patterns are cast integral with their plates, or
are made so by the method of their attachment (fig. 79). This is most

Fig. 79.—Iron Pattern mounted on the Turn-over Table of a Machine
desirable when the jointing faces are irregular, having depressions on one
face and corresponding elevations on the other. These are readily cast,
after which the parts must be smoothed with file and scrape.
One great advantage of plating is that several small patterns can be put
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