is not possible during pouring an open mould to stop at the precise thickness.
The metal is not poured directly into the mould, but into a shallow basin at
Numerous adjuncts are located in these moulds: loam plates, core
plates, and solid grids with prods or prongs distributed over portions of
their surfaces. A pattern prod carrying say half a dozen prongs is pushed
by the moulder into adjacent positions without any particular regard to
Fig. i.—Shows Pattern Frame for Box with Loose Bars moved into successive Positions
A is a diagonal to keep frame square. B, Provision for swivels, c, Prints covering lugs for pins.
exact spacings, the prods therefore being cast with the plate. Wrought-
iron rods of various lengths and outlines are thrust into the mould to
be cast into grids. Long rods with eyes are suspended in the mould,
so that the metal runs round them and amalgamates. Nuts are cast in
when grids have to be retained in their places with screws. Looped
handles are cast in for the lifting of cores.
Large heavy moulding boxes are commonly cast in open sand. The
work is done in successive stages with the help of a limited number of parts.
The pattern box sides are framed entire, but three bars or stays suffice if