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Full text of "Modern Mechanical Engineering Vol-I"

io8

PATTERN-MAKING

1

During the progress of the work he keeps it under observation, both with
a view to save labour and to detect error on the part of the workman, but
without obtrusive interference with the idiosyncrasies of the craftsman,
who often has his own peculiar ways of doing things. When the pattern is
complete the foreman measures it carefully before sending it to the foundry.
To deal with the many thousands of patterns that accumulate, some form
of registration is essential. A pattern register is kept by the foreman, in
which is entered the actual name of every piece and the order for which it
was made, but opposite the name are letters and numbers, and these are
stamped on the patterns. The letters are those of the alphabet, the numbers,
commencing with i, run up to a predetermined limit, 1000 or higher. These
are stamped on the main pattern, on every loose piece, and every core box
belonging to it. If any portions stray in the foundry or in the stores, the
letters and numbers indicate at a glance the pattern to which they belong.
Written orders are sent with each pattern into the foundry, with the date,
the order number, and the number of castings required from it. Error in
moulding, as it affects faced portions or prints and bosses, is sometimes guarded
against by the use of distinctive colours. Thus, while the patterns are pro-
tected with yellow shellac varnish, portions to be faced may be uniformly
painted black or red. Core prints may be painted one colour to distinguish
them from metal.
The Stores*—These occupy large areas, since patterns accumulate
rapidly, and many of them with their boxes are bulky. A storied building
is usual, the heavy work being in the basement, the lighter on floors, for which
tiers of shelves are provided, the widths and spacings of which have to be
in accordance with the general class of work done. Two general systems of"
storage are adopted. In standard work all the patterns of a set are placed
together, the light and heavy. As these are never altered for different orders,
they need not be checked over, but sent complete into the foundry. But
patterns that are not strictly standardized are subject to alteration from time
to time, and this renders measurement and checking for loose pieces and
core boxes necessary for all new orders. For these the practice is to put
all patterns of one class together, from which selections for casual orders
can be quickly made. The letters and numbers stamped on patterns and
their parts show for what previous orders they have been used, and with what
alterations. All the shelves are numbered, and the number of the shelf on
which a pattern is stored and the number of core boxes are entered in the
register. Metal patterns are kept in a separate place, many being hung on
the foundry walls.