If steel ends are needed, their attachment is effected by driving in a small punch and making a hole in line with the axis of the axle, and then welding in a piece of steel, the length of which is according to whether the end of the axle is to be tapered or whether the parallel portion is to be continued to the extremity. If an inch or two of steel is necessary, the pieces are scarfed, or a tongue-joint made in the usual manner.

Crank-shafts of round iron are also made by first forming the two outer curves of the crank instead of first making the two curves at the end of the crank-pin. A long crank-pin is easier formed after the two outer curves are made, and a short crank-pin may be produced at one bending, which is conveniently done at the commencement of the forging.

Those who make small crank-shafts in large numbers require the dies or moulds, into which the iron is pressed and hammered to the shape desired.

These moulds consist of cast or wrought-iron blocks, which are sufficiently thick and heavy to bear much hammering without breaking. They may be so shaped as to produce crank-axles of either round iron or square, and effect a large economy of time and labour.

The lower die or block is that which receives the piece of straight iron that is to be cranked, and the upper block is that by which the work is forced into the die; and both blocks, when together without the work between, form a cavity which is the shape, or, in some cases, nearly the shape, of the crank required. Each pair of shapers is jointed together, or guided together with guide-rods, that both dies may be in their exact relations to each other when brought together by hammering.

But to make a small crank with square corners a different method is adopted. Cranks with angular corners are used for small land-engines, or small pumping-engines, and are of different forms, according to their intended destinations and positions. They are made with but one arm,, having the crank-pin outside, as in Fig. 44, or, as in Fig. 43, with two-arm cranks having the axle-bearings at a distance, depending upon the amount of room desired between the main framing.

The crank-pin represented in Fig. 44 is distinct from the crank-arm, being secured to the arm by a nut, to avoid weakening the pin by cutting a key-way into it. The lever and axle constitute one piece, and the forging of this piece consists in either upsetting the axle and bending it to a right angle, or in cutting a slit into the end of the shaft and welding in the end of the lever.

The strongest work is produced by bending, and the upsetting previous to this bending must be well done; or a larger bar is selected and reduced on each side of the intended apex or corner until the dimensions of the intended lever and axle are attained. This reducing of a bar which is too large is as effectual as upsetting a bar which is about the diameter of the shaft. But whichever plan is adopted, it is necessary to form a thick lump at the place of the intended corner. The inner side of this thick part is then reduced by a broad fuller and hammering, which makes the bending comparatively easy, prevents the inner edges being squeezed up during the bending, and renders the bending process altogether less difficult, while the thick portion outside remains to be formed into the sharp or square corner desired.

The bending or angling is commenced by driving a fuller, which is held on the axle while it is lying across an opening in a large heavy bottom-tool, or some other convenient gap. After being thus partly formed, the angling is continued on an anvil edge, while heavy hammers are held on the work; or the work is put upon a steam-hammer anvil, the hammer of which is fixed upon the work by the steam. While thus fixed, the sledge-hammering is administered sideways to the work.

The final squaring of the corner is accomplished by upsetting it while at a bright yellow heat. During this upsetting, the blows are given both to the cold end of the lever, and to the cold end of the axle. By such treatment, if necessary, a well-defined corner will be produced, without cutting a gap into the corner, and welding in a piece which is named, for some funny reason, a. sticking-piece.

The mode now to be mentioned, of making a small one-arm crank-axle, obviates much upsetting, or large amount of reducing; and is also a quicker method of proceeding than by angling, but care is necessary to ensure good work.

The plan consists in welding the lever to the axle; and requires a large opening or gap to be made in the end, into which is fitted a stem that is tapered down from the lever. The depth to which this gap should extend from the extremity is 11/2 times the finished diameter of the axle Such a depth of gap admits a stem of great strength ; and to allow as much strength as possible to the axle, the bottom of the gap is in the shape either of a long curve or of an angular > form.

If the end of the lever is then spread out and tapered or fullered down to fit the gap, a tolerable joint may be effected with about three welding heats; consequently, every provision must be made to secure sufficient iron for a large amount of welding and hammering. If such a joint happens to be thoroughly welded in all its parts, the work is equal to a shaft made of one piece ; and for many classes of small work such a joint can be made.

The forging of a small two-arm crank-shaft, represented by Fig. 43, includes two or three methods; the particular plan selected depending upon the dimensions of the work and upon the resources of the maker. A simple mode consists in welding and preparing a bar whose width equals the total width of the crank, measured from the outer extremity of the crank-axle to the outer extremity of the crank-lever. When such a bar is made, the crank is formed by cutting out three large pieces: the cutting out of one piece produces the gap which adjoins the crank-pin, and the cutting out of the other two pieces forms the spaces at the outsides of the two levers. After carefully marking upon both sides of the work while cold, the cutting out is commenced at a yellow heat by punching a round hole at each spot which marks the forged width of the lever, and also marks the forged thickness of the crank-axle. Two chisel-cuts are then made at right angles to each other, and whose vertex is the inner extremity of one of the holes. By these two cuts, one of the larger superfluous pieces is cut out; and the other similar piece is then cut out by similar means.

The gap-piece is next cut out by first punching a row of holes which is parallel to the length of the crank-pin, and at the bottom of the intended gap. Two other rows of holes are then made at right angles to the first row, and to meet it; the gap-piece is then separated by a chisel which is driven half way through from both sides. A crank-piece of this character is shown, by Fig. 136.

Crank-axles made by this mode require the iron to be very close and welded in the lever-portion ; if not, the crank will certainly break while in use, although it may be of twice the ordinary necessary dimensions of a good crank for the same engine. And the rupture will occur-because the lengths of the fibres in the levers are at right angles to the proper position. This position is parallel to the length of the lever, and not at right angles to it.

One other method to be mentioned of making a small two-arm crank-shaft consists in making a solid crank, or solid throw, and leaving the superfluous gap-piece to be cut out by drilling and slotting.

The forging of such a crank commences by welding and reducing a bar until the width of it equals the total length of the crank-lever, and then drawing down a portion of the bar-each side of the intended crank.

The length necessary for each end of the axle is discovered by applying the appropriate rule in the ordinary manner; after which a fuller is driven in at the intended commencement of each axle-piece, and the ends are lengthened by ordinary hammering. If the axle-pieces are too short to be reduced while attached to the bar, it is necessary to cut oft' the work, and grip it with angular-gap tongs of suitable dimensions.

The making of large crank-axles will be mentioned in due order.