FIG. 4.
Nails are made both by hand and machinery, the former being called “wrought,” and the latter “cut” nails. For making nails by hand, a hammer and an anvil only are used. The “nailor,” having put several rods of iron of the required size into the fire to get hot, that he may use one after the other, and so lose no time, takes one out and with the hammer beats it to a point, leaving a little shoulder ([fig. 1]). He then places it (at the part where the dotted line is in the figure) on a wedge fixed to the anvil, and with a blow of the hammer divides it; it is taken up by tongs, dropped into a hole in the anvil, and the shoulder beaten flat; this is called a “tack” ([fig. 2]), for a “clasp nail” the head is made of a different form by a particular way of striking it ([fig. 3]), and the form of the hole in the anvil determines whether they shall be square or round; wrought “brads” have the form of [fig. 4]. These are the principal forms of nails, but many others are made by soldering shanks to cast heads, as coffin-nails, and some (chiefly used by gardeners and plasterers for driving into brickwork) are made of cast-iron. Machine-made nails are cut by compression from a sheet of iron. Brads are cut out, simply, as in [fig. 5], which uses up the whole of the iron without any waste, and requires no finishing; but other forms of nails are cut first into simple wedges, and have the heads finished afterwards either by the blows of a hammer or by compression.
CUTTING BRADS.
Most nails are made flat or chisel-shaped at the point, that they may not split the wood. In driving a nail with a flat point, the length of the point should be placed across the grain of the wood, and then it will hardly ever split it, but if otherwise, the nail, acting as a wedge, opens the grain and splits the wood.
SCREWS.
The screws used by carpenters, smiths, and others, for fastening wood or metal-work together, are generally made by machinery. A piece of wire of the required thickness and length is first cut off, which is then placed in a hole or mould, with its upper orifice “countersunk” as in the annexed cut, and the head of the screw is formed by beating the upper part of the piece of wire into the counter-sinking of the mould. It is then called a “blank,” and a number of these blanks are dropped into holes bored round the periphery of a wheel which revolves slowly against a small circular saw driven with great rapidity, and cutting a “thread” or slit in the head of each blank in turn as it comes into contact with it; the wheel continuing to revolve, each screw when it gets to the bottom drops out, so that the holes when they again arrive upwards are ready to receive fresh blanks. The worm, if cut by hand, is made by means of a die of hard steel, having a hollow screw cut in it, which is screwed slowly by a backward and forward movement on to the blank, cutting it into a “worm;” when this is done by machinery, the die is held fast while the screw is worked by a rotatory movement into it. The best screws for wood are slightly tapered, which enables them to be driven much more easily, while they hold equally fast. Large screws for mechanical purposes are cut by a “lathe,” the bar revolving whilst a cutter is held to it, and moved onwards by a pattern screw. Small screws for various purposes can be easily cut by means of a “screw-plate,” having holes of graduated sizes cut inside into hollow screws, which is placed on the end of the wire, and gently turned round till it is sufficiently cut.