Modern Mechanical Engineering Vol-I

EXAMPLES OF WORK

73

heavily foliated capital, cores for these sections must be rammed in boxes
having a central print of the same diameter as the core for the shaft. This
leaves a hole to fit over the
latter.

Cylinder Patterns. —
Most patterns of this class are
divided longitudinally through
the centre, notwithstanding the
fact that they are in the majority
of instances set vertically for
pouring. An exception occurs
in the largest cylinders, which
are moulded vertically, fre-
quently from skeleton patterns,
or swept in loam. A fair num-
ber of moulds of medium
dimensions are taken from loam
patterns, which also are un-
jointed. Patterns of metal are
used for highly repetitive cast-
ings in the smaller bores.
With these exceptions, cylinder
patterns are built with lags simi-
larly to the pipes and columns
just noticed. They have parallel
prints for the main core, usually
head metal, and flanges pre-
pared separately from the body.
All this is simple, plain work.
The difficulties that occur in
cylinder patterns and moulds
are those associated with the
preparation and the setting of
cores, which increase with their
number and tenuity, and are
the most frequent cause of
the rather high proportion of
" wasters " that are produced
in some foundries.

Any cylinder, whether
simple or complex, must be
drawn to actual size on a shop
board, with the machining
allowances and the positions

and dimensions of core prints included, in all aspects and sections. On and
from this the pattern parts and core boxes are tried and checked as the

Fig. 38.—A Fluted Column with Square Base

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