A lever which is represented by Fig. 24, if small, is easily made by drawing down the two ends from a bar which is large enough to be formed into the fulcrum boss of the lever, which is situated near the middle, or, in some cases, near one extremity. Short levers are quickly made by this method, and the work produced is of close, solid character; but for long levers the bosses are separately forged with short stems, and afterwards welded to the smaller portions which are termed the arms. A considerable amount of drawing down is thus avoided, which is often of great importance to a maker with only a small amount of machinery.

In levers of all classes, the fulcrum boss is that which sustains the largest share of the whole strain that is applied to the lever while in use; consequently, this boss is the strongest part. And the lengths of the fibres of the iron or steel in the boss should constitute a series of concentric rings, whose centre is the centre of the boss.

This form is produced by two or three methods; one of which is by selecting a soft fibrous bar, and punching a small hole into that part intended to be the boss, and then drifting the hole to any required diameter while the iron is at a bright yellow heat, or, if the iron is large enough, at a welding heat. The fibres are thus curved, and will have some resemblance to the arrangement desired.

The next method of making a boss consists in using a large bar and placing it between a pair of top and bottom fullers, to reduce the metal on each side of the intended boss. This mode of drawing down produces the required circular arrangement of the fibres without punching and drifting, if the metal at the commencement were large enough, but is a more lengthy mode of proceeding because of the greater quantity of metal to reduce.

One other plan of making a lever boss consists in laying and welding three pieces together, the middle piece constituting the lever itself, and the other two the boss. The two pieces for the boss are of sufficient length to be welded a considerable distance into the arm of the lever.

Upsetting also will produce a lever boss, and is sometimes resorted to in small work. To produce a good boss by upsetting, an excellent tenacious iron or steel is necessary, to avoid risk of splitting.

Those two parts of a boss which project from the two sides of a lever are named the boss-ends. The producing and forming of these ends is effected by driving in fullers and set-hammer; and afterwards by top and bottom die-tools of the required shape, and also by trimming with a trimming-chisel. The shaping by these die-tools or bossing-tools is the cheapest in cases of large numbers of bosses being required. If large bosses are needed, these tools are made in pairs, jointed together, and strong enough for a steam-hammer. For small work the bottom tool fits the square hole of an old-fashioned anvil, the top tool being supported by an ordinary ash or hazel handle in the hand of the smith. Such bossing-tools are not difficult or expensive to make; the simplest variety are not made with guides and jointed together, but are distinct, and are easily bored by a lathe or boring-machine to any desired diameter and depth, according to the length of the intended boss. While making these tools, it is important to smoothly bore the holes, and to make each hole larger in diameter at the entrance than at the innermost end; the hole, being made of regular conic form, will allow the bosses to be driven in and out of the tools with rapidity. The metal around the holes of these tools must be thick, to prevent the tendency to split during a severe hammering.

The use of bossing-tools greatly facilitates the processes of turning and shaping by the boring-machine ; and in many classes of small levers the entire shaping can be done upon an anvil.

In those cases that require levers to be finished without turning or boring, the joint-pin holes or connecting-pin holes are punched and drifted to the finished diameter; and a square is used to ascertain if the hole is at right angles to the length of the lever. A drift is driven tight into the hole, and, while in, a square is applied to both sides of the two arms of the lever; or to both sides of one arm, if the boss under treatment is at the extremity of the lever. And if the drift is not parallel to the blade of the square, the hole is not at right angles to the lever, and must therefore be altered, until a near approach to the desired position is attained.

The adjusting consists in bending one arm, or both arms ; and sometimes a twist is needed. Twisting is effected in small work by tightening one arm of the lever in a vice, and twisting the other arm by applying a twisting-lever (Fig. 102). If a vice is not near, two of these twisting-levers are used, one upon each arm of the lever that is to be adjusted ; while the smith holds one twister, the hammerman holds the other, and each man pulls in opposite directions, by which the adjustment is easily effected if the work is sufficiently heated. To twist a large lever it is only necessary to place the boss or one arm upon a steam-hammer anvil, and to gently let down the hammer to the arm or boss, and there to fix it by the steam. While thus fixed, twisting-levers are applied to one arm, or to both arms if necessary.

Another kind of adjustment is needed when the two faces of the boss or bosses are not parallel to each other, or not parallel to the lever-arms, or not at right angles to the sides of the lever boss. In such cases the hole is first adjusted to a right angle with the arms, the boss is then pared by a chisel to produce the necessary parallelism with the hole; after which, the two prominent projections are trimmed off the two faces.

The lengths of the fibres in the lever-arms require to be parallel to the length of the lever itself, to avoid sudden breaks. For many varieties of small levers Bessemer steel is used, and, if of soft fibrous character, is very advantageous for the production of smooth friction surfaces for the joint-pin holes. Levers that are made of steel are drawn down from a piece which is sufficiently large to produce the fulcrum boss of the lever ; and by applying the author's rule, no steel need be wasted, through not knowing the length of metal necessary, previous to drawing down.