When one boss is thus roughly shaped, the work is cut to a proper length, and the other boss is produced in a similar manner: the lump in the middle for the arm is then reduced to the requisite width, thickness, and length. (See Fig. 159.)

Small crank-levers are also made of two pieces without resorting to curving or upsetting, as in Fig. 160. According to this mode, the upsetting of the bosses is avoided by using iron of the requisite sectional area to- make a solid boss, and from the boss half the lever is produced by drawing with fullers and hammering while the boss is being formed at the end of the bar. The boss and part of the arm being thus formed, the work is cut from the bar, and another boss-piece is formed of the same bar, if necessary.

This plan is the shortest that can be adopted for making a crank-lever of two pieces. The only existing objection to the method is that the constituent fibres at the outer extremity of the boss are parallel to the length of the lever, because they were parallel to the bar previous to forging, and no alteration of relative position has since been effected.

A partial remedy for this consists in punching a hole into the boss, and giving a few welding heats and hammerings to it while a drift or mandril of some sort is in the hole. When it is intended to adopt the welding for this purpose, sufficient iron is allowed for the boss being burnt by the several heatings.

Small levers having bosses of great length are made also by bending and piling. For this purpose three or four bars are selected whose thickness is about equal to the intended thickness of the metal around the boss-eye or hole. The bars are bent to a circular form which is smaller in diameter than the desired boss, and a sufficient number are employed and piled together to produce a boss about 11/2 times the length of the finished boss. This pile is then heated to welding, and upset, by which the boss is shortened in length and increased in diameter to that which is necessary. Such piles are represented in Fig. 161.

The loose straight ends of the bars are next welded together for producing the arm of the lever. To this another boss-piece is welded to complete the lever.

Fig. 162 represents a crank made by closing together a ring, and welding the middle to become the arm.

For large crank-levers several pieces are needed, both for portability and to produce the desired arrangement of fibres without a difficult bending of thick bars.

Lever-bosses for large crank-levers may be conveniently made of several thin bars, which are separately curved and then welded together. The thinner the bars for this purpose, the easier will be the bending, and the greater is the number that will be required. The width of the bars is about the length of the intended boss, and their length should be only sufficient to extend round the work and allow the ends of the bars to be welded together, or to a straight bar that may be between.

The manner of bending consists in heating a bar to about welding heat in the mid-part, or in that part which is to be bent. The bar is then put between a set of bending-rolls, or under a steam-hammer, and across a bottom-tool or anvil-block having a deep curved gap. A cylindrical filler or piece of round iron is next put upon the bar and driven down by a few blows with the hammer, the hammer being of sufficient length to reach and strike the filler without coming into contact with the two ends of the bar which are being forced up by the filler being driven down.

When partly curved, the next bar is treated in a similar manner ; or if only one bar is in progress, the filler is taken off and the bending continued at the next heat by striking the ends of the bar until both are near enough together to fit the middle bar, and a small hole remains representing the boss-eye. A welding heat is next given, and a pair of fullers are applied to thoroughly weld that part of the work immediately adjoining the hole, being careful not to close or flatten the curved part at the extremity. The straight ends are next soundly welded to the middle bar, and the work becomes a sort of nucleus for the reception of other bars. (Fig. 165.)

One bar being thus bent and welded to the primary or middle bar, another is bent in a similar manner, but with a larger filler, which is about equal in diameter to the diameter of the boss in its present condition. This second bar is next welded to the work, and fullers again employed to thoroughly weld that part near the hole. (Fig. 166.)

If the second boss-piece is not sufficient to increase the boss to its desired diameter, a third piece is bent and welded to the work in a similar manner.

When all the welding that may be required by the fullers is completed, but not till then, that end of the primary bar that protrudes into the boss-eye may be punched out; and the welding of the boss may then be completed while on a filler or mandril in the boss-eye.

To conveniently weld the boss, a short porter is attached to the arm or lever portion of the work, and the boss is heated to welding in a furnace which is large enough to heat the entire boss at one heat. During the time of heating, the filler or mandril is put beneath the hammer and supported at each end, allowing sufficient space for the lever-boss to be raised or lowered by the chain which is attached to the porter, so that the boss may be partly rotated on the filler during the hammering for welding.

The work is next put beneath the hammer while the mandril is being put into the hole, and the welding of the boss is effected with two or three heats.

The next operation, after welding the boss, is to determine which is to be the centre line of the lever, also what point in this line is to be the centre of the boss-face, or, as it may be termed, the boss-end. A piece of wood is fixed for a short time in the hole at that end of the boss which is to be the end projecting from the lever-side when finished. The centre of the boss-face is then determined, and a circle marked with compasses; the diameter of this circle being the diameter of the boss when forged. A chisel with thick cutting edge is then driven in at the circle, and the work heated to produce the required boss-end that is to extend from one side of the lever.

This projection is formed by driving a top-fuller into the lever at the circular chisel mark. When a gap is thus made , the remaining thick lump of the arm is reduced by hammering to the necessary width and thickness.

Bosses thus made with half the lever are welded together by means of a tongue-joint about the middle, so that if the ends attached to the bosses are too long, they are cut to length and trimmed to shape while preparing the joint-ends for welding.

By reference to the Figure 168 it may be observed that the joint is of great length in order to secure a sound weld and thereby a good lever. The welding of the joint is effected by placing the two pieces together in one fire or furnace that is open at two opposite sides, and welding while in the fire with a pendulum-hammer. If a convenient furnace of this character is not accessible, the two pieces of work are separately heated in two fires, and put together, end upwards, under a steam-hammer, and welded by upsetting. Another welding-heat or two is afterwards given to complete the welding of the sides and edges, and to drive in the prominent scarf-ends.

Shaping and trimming the lever is next performed; after which the two bosses are trimmed with chisels and smoothed to their forged dimensions. The lever is finally made red-hot from one end to the other, all scale and clinker scraped off, and the work allowed to gradually cool.

Crank-levers made by this mode have a hole in each boss, so that a great amount of boring is avoided, in addition to the advantage of securing a strong lever.

To avoid the bending processes, crank-levers having bosses of great length are made by piling and welding several bars together until the desired length of boss is attained; the bosses thus made being without any hole to the end of the forging. A pile of this character is represented by Fig. 169.

After a few short bars are thus soundly welded together with several heats, the extremity is tapered on two sides ; this taper or curved part being on those two sides of the work that are intended to be the boss-sides, and not the boss-ends. The taper part is next heated to welding and put beneath a hammer with the cool end of the work upwards, and the end at welding heat in a bottom tool having a sharp curved gap. While in this tool, the work is upset with a few heavy blows, to produce an approach to the desired circular arrangement for the boss-fibres. Two or three such upsettings are administered, after which the fullers are driven in at the place intended for the junction of the boss with the lever; and thus the circular form for the boss is obtained The boss-piece then appears as in Fig. 170.

The bosses made by this process have stems or arms that may be of sufficient length to be made into the lever, and also the boss at the other end of the work; or another solid boss may be made, and the two stems or arms welded together to complete the lever. (Fig. 171.)