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Full text of "Modern Mechanical Engineering Vol-I"

120

FOUNDRY WORK

are located with dowells, and in long patterns like that in figs. 3 and 10,
if made in timber, warping in the transverse and longitudinal directions

Fig. io.~Pipe Pattern not Jointed for Turning Over.   Shows method of fitting flanges loosely in grooves

is less liable to occur than in a pattern that is made in two portions. But
as the top box must then be lifted off the pattern, it is better to leave the
flanges loose, because they have vertical faces.

Fig. ix.—"Jointed Bracket Pattern

Fig, 12.—Jointed Bracket Pattern

JE3SL

Three examples of brackets in which the jointing coincides with that of
their moulds are given in figs, ir to 13.   In the first the joint is along the

middle plane of the web, in the second
along its top face. If these were not parted
as shown, the lifting of the cope sand off
the vertical rib would fracture the sand, to
avoid which the rib alone is often left loose,
and the upper portion of the boss and of
the foot made fast. In fig. 13, the upper
boss and its bracket, shown dowelled, are
often made fast. Each of these patterns
might alternatively be moulded sideways,
that is as they lie on the paper.

Fig. 14, the radial arm of a drilling
machine, should properly be jointed in
the plane aa, and moulded by turning over, but bedding-in offers no
special difficulty. The prints for the column core are dotted at A, A; the
overhanging portions of the facing for the saddle must be loose, as at B, B.

Fig. 13.—Jointed Bracket Pattern