Fig. 260.

In relation to stamping with the drop hammer, which has come in for a considerable increment of usefulness during late years, in many forms and capacities, it may be generally stated that all those remarks made upon swaging, in both loose and fixed blocks under the steam hammer, are equally applicable - Section III. Part I., Forge. Drop hammers may be obtained of various designs, and sometimes embrace many ingenious mechanical devices, They are sold by the makers of steam hammers, and also they are frequently rigged up by the intending user, out of convenient material in convenient places. When the latter plan is resorted to, it frequently happens that the well-known appliance in the tin shop is copied on a larger scale, and of heavier dimensions. In other designs the head is raised by means of an attached hoard, which passes through friction rollers, regulated by a foot-treadle, the upward progress being checked by adjustable collars on the upright. Sometimes arrangements are also provided to give repeated and variable blows. Fig. 262 gives four views of the hammer head, as an example, and Fig. 263, the top and bottom die. Mild steel castings make serviceable dies, but of course whether the dies are forgings or castings, the object to be stamped has to be carved accurately in them. This is done by working rigidly to centre lines and machining as much as possible, planing, drilling or shaping; but the chief work lies in careful and patient fitting. After the fitter has finished they are braced together and tested, by running in a composition of lead and bismuth, and when accurately coincident they are finally marked, so as to facilitate the preliminary adjustment in the hammer.

Fig. 262.

When fixed for working, they are first tried upon a lump of stiff clay. It is reasonable to expect a production of a thousand articles without serious detriment to either die. Those shown have carved in them the end or joint of the reversing shaft, the finished product being given in two views to the right. Other articles produced by this means are: - Fig. 264, the valve-spindle cross-head; Fig. 265, adjustable spring link; Fig. 266, a short-armed lever; Fig. 267, a small standard for communication cord, and also an infinite variety of signal work. The fin produced is removed by an auxiliary die, which is illustrated by Fig. 268, being the arrangement for the adjustable spring link, Fig. 265.

Each engine is, of course, thoroughly equipped with all necessary tools, spanners from ⅝ to 1⅞ inch, box and gland keys, rakes, shovels, pricks, darts, chisels, etc. It is obvious that the cheapest method, taking all things into consideration, in the production of spanners, is the drop hammer, in which case they are made to the following section (G). The method now further illustrated, will certainly compete in economy of time, but there is the element of waste in the scrap formed by punching, and the spanner on the whole is heavier than that produced by the drop hammer. As there is no welding about them they are a strong job, and there is not any risk of the jaw breaking. The punching block and die for ⅞ and 1 inch double-ended spanners are shown in Fig, 269, A being a plan and B the end elevatiori. They can be punched as quickly as the rolled or sheared strip of mild steel can be pushed through, there being two punches, one working whilst the other is drawn out and got ready to take its turn. After the whole order is punched, the ⅞-inch ends are finished first, followed of course by the 1 inch. The finishing process occupies one heat only, the first operation being to round the edges in a pair of swages C, Fig. 269, immediately lifter it is put into the die D, a dummy placed upon the top to keep the die from spreading, punched and finally dressed up on the anvil, of which, needless to say, little is necessary. Fig. 270 is a useful combination used is the production of chisels.

It is one of the many examples which might be illustrated to show how division of labour produces its own means to facilitate certain ends. It is used in heading, A being an adjustable guide for the length, B a peg which prevents undue wear and tear or injury to the swage C, which heads two at once. They are then sheared by a somewhat similar arrangement, the peg in this case preventing the blade of the shear coming upon the anvil, each combination tool weighing but a few pounds. After shearing, the chisels are drawn down upon a taper plate, and half-a-dozen can easily be made at one heat from bars of the required section. The enormous quantity of nuts and bolts are made by machinery, either by swaging or heading. The swaging machine has a range from « to 2 inches by change of dies. Bolts with hexagonal heads are made from round bars, but those having square heads from square bars. The dies in the Ryder machine never close by ⅛ inch, so that there shall not be any risk of damaging them. The machine is fixed, in close proximity to the smith's hearth; immediately beyond is the hot saw, and in front of the latter is a square anvil, in which is placed the former A, Fig. H, for shaping the head, the chamfer being made by a snap. In the heading machine any length of bolt can be dealt with, but each has its range of work as to diameter, both for nuts and bolts, say « to 1 inch, and 1⅛ to 1⅛ inch in bolts, the latter making from 1 to l«-inch nuts.

Horsfall's beading machine first produces a "bunt." formed thus, Fig. I, which is then lowered down into the next pair of dies and finished by a snap and hammers, Fig. J. The nuts made in these machines are quite solid, and they do not make any waste. The punching from one nut goes to help to form the next, whereas in the Collier machine there are two punchings which go into the scrap box. The range of the latter machine is up to l«-inch nuts and washers. In this case bar iron must be used about ⅛ inch thicker and 1/16 inch narrower to allow for compression and flow during the act of punching. Rivets are made in machines of the De Bergue type, which are heading. The thickness of the nuts is the same, whether hexagonal or square, and generally equals the diameter of the bolt, excepting in some cases, such as gland nuts, where it is a practice to make them ⅛ inch thicker. The thickness of lock nuts is two-thirds the diameter of the bolt, omitting fractions below 1/16 inch, which is also the ease with snap heads, the width of the latter being equal to that of the nut across the sides, Fig. K. The large radius A equals twice the diameter of the bolt, and the small radius B half of the diameter. The angle of countersunk bolts is made 30° with the vertical, the diameter of the head being equal to the width of the nut across the sides; therefore the depth determines itself. The nuts are to Whitworth's standards. The ferrules of the tubes are made from steel strips rolled to section, cut to length by the smith and welded by an oliver, on a mandril in a die. This method has been surpassed by cutting steel tubes of required diameter to length, and putting the necessary taper on by a drifting machine.

Fig. 267.

Fig. 268.

Fig. 269.

Fig. 270.

Fig. H.

Fig. I.

Fig. J.

Fig. K.