THE TURNER.
1. Turning is a very useful art, by which a great variety of articles are almost exclusively manufactured. Besides this, it constitutes a considerable part of the operations of several trades and occupations, such as the chairmaker, machinist, cabinet-maker, brass-founder, &c., since every substance of a solid nature can be submitted to the process.
2. Turning is performed in a lathe, an apparatus constructed in various ways, according to the particular purposes to which it is to be applied, although, in all cases, the general principle of its operation is the same. The kind represented in the above picture, is used for plain or circular turning in wood. On examination, it will be perceived, that two wheels of different sizes make essential parts of it. On the extended axle of the smaller one, is fastened the piece to be turned; and immediately in front of this is the rest, on which the cutting instrument is supported during the performance of the operation.
3. When the material to be turned is wood, it is commonly cut to the proper length with a saw, and brought to a form approaching to the cylindrical by means of an axe or drawing-knife. It is next fastened in the lathe. This is done by different means, varying according to the particular form of the thing to be turned. In plain circular turning, as applied to bed-posts, legs of tables, and rounds for chairs, the piece is supported at each end. That at the left hand is driven upon a piece of steel, which has been screwed upon the extended axle of the small wheel; and the other end is fixed upon a steel point, placed in an upright moveable piece called a puppet-head.
4. In case the wood is to be turned on the inside, as in making a bowl, cup, or mortar, the piece is supported altogether at one end, by means of a hollow cylinder of wood, brass, or iron, called a chuck, which receives it on one side, and on the other is screwed upon the end of the axle. The axle is sometimes called the mandril, and any extension of it, by means of a piece added to it for a centre, on which anything may be turned which will admit of a hole through it, is denominated an arbor.
5. The tools used in turning wood and ivory, are gouges and chisels of different sizes and shapes. In using these, they are placed upon the rest, and brought in contact with the revolving material of the proposed figure. The gouge is employed in cutting away the rough exterior, and the chisel, in producing a still further reduction, and a greater smoothness of surface.
6. In working in very hard wood and in ivory, the grooving tool, a sharp pointed instrument somewhat similar to the graver, is used in the first part of the operation; and by this the grain of the substance is cut into contiguous grooves, and prepared for an easy reduction by the chisel. The instruments for turning metals are numerous, but they differ in some respects from those for cutting wood.
7. In almost every kind of turning, a tool called the calipers is necessary for measuring the diameters of the work. In its form, it bears some resemblance to the compasses or dividers. One or both of the legs, however, are curved; and one kind of this instrument has four legs, two curved, or two straight, at each end, with a pivot in the centre, on which it is opened and shut. The former of these is employed in measuring the dimensions of outside work, and the latter, for that on the inside. This kind is called the in-and-out calipers; and it is especially useful in turning a cylinder, or pin, which shall exactly fit an internal cylinder already made, and vice versâ.
8. There is but little difference in the management of turning different substances. The principal thing to be attended to is to adapt the velocity of the motion to the nature of the material; thus wood will work best with the greatest velocity that can be given to it. Brass should have a motion about half as quick as wood, and iron and steel still less; for, in operating on metallic substances, the tool is liable to become hot, and lose its temper; besides which, a certain time is requisite for the act of cutting to take place.
9. When compared with many other mechanical operations, the art of turning may be considered as perfect in its accuracy and expedition. The lathe is, therefore, resorted to for the performance of every work of which it is capable; nor is its use confined to the production of forms perfectly cylindrical, for it can be easily made to produce figures of irregular shape, such as lasts, gunstocks, &c.
10. The lathe was well known to the Greeks and Romans, as well as to many other nations of antiquity. Diodorus Siculus, who wrote in the time of Julius Cæsar and Augustus, says that it was invented by one Talus, a nephew of Dædalus. Pliny ascribes it to Theodore, of Samos, and mentions one Thericles, who had rendered himself very famous by his dexterity in managing the lathe. The Greek and Latin authors frequently mention this instrument; and, among the ancients, it was customary to express the accuracy and nicety of a thing by saying, it was formed in a lathe.
