Turning

Turning, the art of shaping wood, metal, ivory, or other hard substances into forms having a curved (generally circular or oval) transverse section; and also of engraving figures composed of curved lines upon a smooth surface, by means of a machine called a turning-lathe. The immense variety of work performed by turning-machines necessitates great variations in their construction; but their mode of operation is always the same, and consists in fixing the work in position by two pivots or otherwise, causing it to revolve freely round an axis of revolution of which the two pivots are the poles, and holding a chisel or other cutting-tool so as to meet it during its revolution, taking care that the cutting-tool be held firmly and steadily, and moved about to different parts of the work till the required shape be obtained. Lathes are divided, with respect of the mode of setting them in motion, into pole-lathes, foot-lathes, hand-wheel lathes, and power-lathes; with respect to the species of work they have to perform, into centre-lathes, which form the outside surface, and spindle, mandrel, or chuck lathes, which perform hollow or inside work, though this distinction is for the most part useless, as all lathes of good construction are now fitted for both kinds of work. Bed-lathes are those used by turners in wood, and bar-lathes for the best sort of metal-work; and the small metal centre-lathe used by watchmakers is known as a turn-bench.