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Full text of "Modern Mechanical Engineering Vol-I"

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The foregoing descriptions relative to the making of moulds apply sub-
stantially to the preparation of cores.
That is, these may be (a) rammed in
green or preferably in dry sand, (b)
swept in loam with revolving or with
fixed boards, or (c) made with strickles.
Generally, the same provisions have to
be made for cores as for patterns, in
the shape of taper, in the employment
of loose pieces and prints for inserted
cores, and for shrinkages. Taking suit-
able precautions, there is no casting so
intricate that it cannot be produced
with the help of cores. As the support
of a moulding box is not available, a
large amount of detail is associated with the supporting elements around
which cores are rammed. These are round rods and wires in the smallest,

Fig. 28.—A Core being swept against the edge
of a Board on Trestles

Fig. 29.—Core swept on Bar for Fusee Barrel, fig. 16.   The section of the casting is drawn on the board
for the information of the moulder

and grids of multifarious forms in those of large dimensions.   For loam
cores made by rotation against the edge of a board, stiff cylindrical bars