7.068 : 3.141 : : 11 : 4.889 The first of these terms represents the mean sectional area, in inches, of that portion of the rod which is to be forged into a key-stem. The second term denotes the mean sectional area of the required stem. The third term indicates the length, in inches, of the key-stem to be forged. And the fourth term points out the length of bar or rod required, to produce eleven inches of stem without requiring any portion to be cut oft* the stem when finished.

The proportions indicated by the symbols are not true; they are merely arithmetically correct to the extent of the fractions employed. But, practically, we find them valuable, because they inform us that four and nine-tenths inches of steel is sufficient for eleven inches of key-stem. This being known to the smith, he should put a small dent into the steel by means of the chisel for cold steel, at five and one-eighth inches from the end of the steel. This distance is more than that which is indicated by the symbols, because a small portion will be taken from the steel by heating, and the end of the stem will be unsound and may require welding or cutting off.

To ensure the necessary soundness at the end, it is curved, either by welding or by cutting off any ragged or hollow portions; and this must be done previous to any attempt to draw down by the fuller or steam-hammer; because, if the steel is hollow at the end, at the time of commencing to reduce it by the steam-hammer, and the steel too brittle to be welded, it will become worse under the hammer, which will in a short time break it to pieces.

This curving just mentioned is also important for iron keys, either large or small, and is always necessary in proportion to the amount of drawing the metal is to undergo, when it cannot be welded again after being made unsound.

The end being curved, or what is termed rounded, and the dent put into the steel at the proper place, by means of what is named the cold chisel, it is proper to commence drawing down by driving in the fuller, to produce the shoulder. When the fuller is driven to about half the depth that will be reached when finished, draw the lump which is to form the stem to a square; after which, drive in the fuller again at the shoulder, and make the gap deeper to admit of the stem being again drawn upon the anvil - remembering to make the key four-sided, and to commence the drawing down at the shoulder of the key, and draw the work towards you a short distance, after each blow from the hammer, until the extremity is reached; then commence the drawing again at the shoulder. The key-stem will, by such treatment, become compact, and, if the steel is good, rather improved, but not if hammered while it is much below the red heat. If the key is being made of iron, the openness of the grain is partly closed by hammering at a proper heat; and keys require a very close texture to prevent splitting when the strain of the lever or shaft is applied to the side. If the key should be made of layers of iron, welded together, instead of steel, the layers should be placed parallel to the side of the key-stem; in this position the strain upon the key-side will tend to close the key together; but if the layers of iron are parallel to the shaft, and the iron bad, there is a danger of the key being split into two, and one piece being carried round by the lever, while the other piece remains in the key-bed.

The four-sided shape of the key is now to be altered to eight-sided, by placing one corner upwards to receive the hammering, and afterwards the others, until a tolerable approach to eight-sided is attained; after which, round the key-stem by the top and bottom tools (Fig. 64), and adjust the key to its proper diameters at each end, by the half-round top and bottom tools, at which time the double-gap gauge or the two pairs of callipers will be required to ascertain the size ; and the straight-edge will be useful to ascertain if the stem requires straightening.

These remarks equally apply to small keys. The four-sided and octagonal forms are easily attained by the hand-hammer, and the learner will be pleased at the mechanical method just indicated.

The particular uses, and pieces of work, to which round keys should be applied shall be treated in another place. It is now necessary to mention the methods of upsetting to form the head ; and the doubling of the iron to form the head.

Instead of commencing by making the stem, as in the drawing down, the head is first formed at the end of the bar by battering it, either in the horizontal position while lying on the anvil, or in the vertical position while standing on the anvil, or on a heavy cast-iron block, the top of which is level with the ground, if the work is too long to be stood upon the anvil. Till the present time, all the laborious upsetting, both of small work and large, has been done by manual labour of a tiresome character. Although our wonderful and valuable assistant, the steam-hammer, will upset a short piece of iron or steel, if it be only one or two feet in length, we cannot use our powerful friend to upset a long rod or bar without some means of making the steam-hammer strike the iron while in a horizontal position. This object is now conveniently accomplished by what is called Davies's patent steam-striker, which is an appropriate term, because the machine will deliver blows at any angle from horizontal to vertical, thus avoiding much of the troublesome upsetting by the hammerman. But if without such a contrivance, it is necessary to use the pendulum-hammer, if the bar is very long, or to cut off the piece to form the key, and upset it upon its end. The upsetting of iron generally should be done at the welding heat; the upsetting of steel, at the yellow heat, except in some kinds of good steel, that will allow the welding heat. And both iron and steel require cooling at the extremity, to prevent the hammer spreading the end without upsetting the portion next to it. If the head of the key is to be large, several heats and coolings must take place, which renders the process only applicable to small work. A small bar can be easily upset by heating to a white heat or welding heat, and cooling a quarter of an inch of the end; then immediately put the bar to the ground with the hot portion upwards, the bar leaning against the anvil, and held by the tongs (see Fig. 68). The end is then upset, and the extremity cooled again after being heated for another upsetting, and thus till the required diameter is attained. When a number of bars are to be upset in this manner, it is necessary to provide an iron box, into which to place the ends of the bars, instead of upon the soft ground or wood flooring, injury to the floor being thereby prevented.

When the key-head is sufficiently upset, the fuller and set hammer are necessary to make a proper shoulder, the stem is then drawn four-sided and rounded by the 0 top and bottom tools. If the bar from which the key is being made is not large enough to allow being made four-sided, eight sides should be formed, which will tend to close the grain and make a good key.

The third method of making keys with heads is the quickest of the three, particularly for making keys by the steam-hammer. By its powerful aid, we are able to use a bar of iron an inch larger than the required stem, because it is necessary to have sufficient metal in order to allow hammering enough to make it close and hard, and also welding, if seamy. If the bar from which it is to be made is too large to be easily handled without the crane, the piece is cut from the bar at the first heat; and the length of the piece to be cut off is determined by aid of the rule given in page 8. But if the bar is small, it can be held up at any required height by the prop, shown in Fig. 69. While thus supported, the piece to be doubled to make the head is cut three-quarters of the distance through the iron, at a proper distance from the extremity. The piece is then bent in the direction tending to break it oft"; the uncut portion being of sufficient thickness to prevent it breaking, will allow the two to be placed together and welded in that relation. A hole may also be punched through the two, while at a welding heat, as shown by Fig. 70. The hole admits a pin or rivet of iron, which is driven into the opening, and the three welded together. This plan is resorted to for producing a strong head to the key without much welding; but for ordinary purposes it is much safer to weld the iron when doubled, without any rivet, if a sufficient number of heavy blows can be administered. At the time the head is welded, the shoulder should be tolerably squared by the set-hammer; and the part next to the shoulder is then fullered to about three-quarters of the distance to the diameter of stem required. In large work the fuller used for this purpose should be broad, as in Fig. 71. After the head is welded, and the portion next to it drawn down by the fuller, the piece of work is cut from the bar or rod, and the head is fixed in a pair of tongs similar to Fig. 72. Such tongs are useful for very small work, and are made of large size for heavy work. Tongs of this character are suited to both angular work and circular. They will grip either the head or the stem, as shown in the Figure. While held by the tongs, the thick lump of the stem that remains is welded, if necessary. Next draw the stem to its proper shape, and trim the head to whatever shape is required.