Pattern
In moulding, the pattern is a counterpart of the casting required, from which the moulder obtains an impression in sand or other plastic substance. This impression obtained, it remains to fill the space, previously occupied by the pattern, with molten metal, which when solidified is a true representation in metal of the pattern supplied, less the shrinkage. Patterns are sometimes called models, from the fact that the modeller furnishes patterns for both the brass and iron foundries made from plaster or stucco. Wood patterns made by the pattern-maker are by far the most numerous, including as they must patterns for nearly every cast piece used in producing the multitudinous examples of structural, machine, and engine work. Very much of moulding is now accomplished without a full pattern, when a good understanding is maintained between the moulder and the pattern-maker. By a judicious arrangement of strickles, making-up pieces, and sweeps, castings are very often made almost exclusive of a pattern altogether; but this only occurs when the ability of both artisans is above the average. Machines for moulding gears have reduced pattern-making for wheels to a fraction of what it formerly was, and numerous other castings may, by the aid of a segment and perhaps some core-boxes, be made by them as readily. Besides patterns in iron and brass, numerous others are the production of the modeller, made in stucco or plaster, and not a few are, with the aid of template and sweeps, made in loam by the moulder himself. See LOAM-PATTERNS; BACKING-OUT; SPINDLE.