PINS.
PIN-MAKING MACHINE.
COIL FOR THE HEADS.
Pins are made from brass wire drawn out in the usual manner (see “[Wire-drawing]”). It is first straightened and then cut off into lengths sufficient for two pins; these are pointed at each end by holding them to a wheel, about two or three dozen at a time, turning them all round at once by means of the thumb and fingers. The wheel is not made of stone, but of steel, having the edge cut into fine notches like a file (see “[File-cutting]”). After the wires are pointed at each end, they are cut in the middle. The heads are made by coiling some brass wire round another piece of wire exactly the size of the pins for which they are intended, and with a sort of chisel cutting off two of these coils at a time. The accompanying figure represents the coil to be cut up into a string of heads, and one of them separate. These are fixed on to the pointed wires by a machine acting by means of a lever, by which they are compressed into the right shape and at the same time made to hold on tightly. The pins are then cleaned by boiling in some weak acid or a solution of tartar, and have next to be “tinned” or “whitened,” which is done by placing them in layers with grain-tin and cream of tartar, and boiling them for some time till they are coated with the tin; thus they are truly “electro-plated,” although at the time when this process was invented no knowledge of electro-plating existed, and the theory of the process was not understood. The pins are afterwards cleaned and brightened by shaking them in leather bags with bran, which is afterwards blown away by a blowing-machine; the pins are then placed in papers (folded by a sort of crimping-machine), which are put into a kind of vice, having a number of notches cut in it corresponding to the number of pins to be stuck in one row, and into these notches and through the paper ridges the pins are rapidly passed by children.
In some manufactories pins are made entirely by machinery, and these are the “solid-headed pins,” or pins which have the head formed out of the same piece of wire as the body, which is chiefly effected by compression, and in order that this may be readily done, the wires are previously softened by heat, which is one of the principal objections to their general use, as, in consequence of this softening, they bend too readily.