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Full text of "Modern Mechanical Engineering Vol-I"

98

PATTERN-MAKING

on a plate, which in ordinary moulds would be arranged by hand, and that
all ingate patterns can be included, instead of cutting the channels laboriously
in every mould (fig. 80). The economies of these last developments are
such that the moulds for twenty or more small castings may often be made

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Fig. 80.—Four Patterns mounted on a Plate

in the time that would be occupied for one in hand-work by the ordinary
method of turning over.

8. SECTIONAL AND  SKELETON-LIKE PATTERNS
Both these are employed extensively for the largest castings when required
in small numbers, in order to economize timber and labour. Extra work is
always thrown on the moulder, but the question is one of relative cost. It
is rather remarkable how much can be done with strickles, sweeping blocks,
and skeleton frames, with the assistance of cores for dealing with the interiors.
Often the pattern-maker has to spend a considerable time in the foundry
assisting in the setting of parts and the checking of measurements.
Sectional Patterns.—This term includes a large variety of work,
:haracteristic of which is that the provision for making the moulds
_sts of strickles, strips, sweeps, boards, bosses, facing pieces, prints, and