As illustrating how any number of dies may be readily made to one standard size and shape, take the case of a cutting-out die for cycle-chain links. It is possible to make dies or beds of this kind by the hundreds, so that they shall not vary more than one thousandth part of an inch. Figs. 90 to 93 show a good method of making these and similar tools. A standard bed and punch would first be made by the method described by figs. 83 and 84, for making standard dies and punches. The bed would be called the standard bed, and must necessarily be made very carefully; in fact, both bed and punch must be made absolutely accurate, the punch being sized so that it can just be pressed into its bed or die, being what is known to a tool maker as a tight fit.

Fig. 90.

Now, referring to fig. 90, the die is seen in plan at A, and the inverted plan B shows the bottom of the die; between A and B the die is seen in section. Supposing this standard die to have been finished, hardened, and tempered, the next step is to prepare an accurate drift, with which it may be finished, or sized and corrected, so that all subsequent dies will be alike in shape and size. This drift will deal with the bar H H of the die, fig. 91. The method of dealing with the round holes or large ends of this die may for the present be left out of the question, as that portion of the work requires separate attention. To make the drift, procure a piece of tool steel about 3 in. long, and of such sectional area that will allow it to be shaped up for its whole length, the same shape as the hole in the standard die, figs. 90 and 91. Having first filed up the ends and covered them with sulphate of copper, mark out the shape on each end, and indicate by small centre dots, plane or shape it from end to end by means of the shaping machine, afterwards carefully file it with suitable files until it is possible to pass the drift straight through the die with the assistance of light blows from a hand hammer. It is not an easy matter to make this drift, and it requires the greatest, possible care and judgment to be exercised during each step in the process, and the micrometer gauge should be used throughout, for if the drift was carelessly driven through the standard die a tight driving fit it would be liable to burst the die, in addition to the drift being so ripped and knocked about as to make it absolutely useless.

Fig. 91.

The standard die, fig. 90, is used more as a guide to shape, and to enable the extreme ends of the drift to be fitted with the die, rather than to be used for forming the general shape of the drift for its entire length. This must be done by careful filing, when the drift has been made perfectly parallel and of uniform shape. The next step will be to file a clearance or taper for about half its length, leaving l 1/2 in. parallel. At the end of the clearance make a distinct bevel, so that a hammer may be used freely upon this bevelled end, which may now be called the head of the drift, seen at T, fig. 92. At the other end of the drift it will be necessary to file away the centre S, in the manner shown at fig. 92, thereby forming two small horns b. These horns are important to the successful use of the drift, as their office is to fit round holes in the die, thereby guiding the drift, and helping to keep the drift perfectly perpendicular, whilst the bar part of the drift is rectifying the bar part of the die. The drift being finished may now be hardened and tempered its entire length to a dark straw colour, and attention may now be directed to the use of this drift

Fig. 92.

Fig 93.

The die, fig. 91, having been marked out and had the two larger holes drilled by a method that will be explained later, it will be seen that these two larger holes represent the ends of a cycle-chain link. The drilling of these holes will leave a distance between them in the form of a bridge, from hole to hole. This bridge is known as the bar part of the die. To remove the metal of this bar, first drill two small holes H1 H, fig. 91 (C), either by the use of a special jig or otherwise, then plug up these two small holes by driving in soft iron wire, and file them off level (see section of die at D). Having plugged the small holes, a third hole may now be drilled directly in the centre (see section of die at E). Now remove the part of the plugs that remain, and carefully chip and file away the bar, leaving a few thousandths of an inch to be removed by the drift. Fig. 92 shows the die in section, and it will be noticed that the drift is in position ready to be driven through. Another section is shown at F 2, fig. 93; and a third section of the die, F3, shows the centre or bar part of the drift only as it passes through the die.

Fio. 94.

The standard die or bed, fig. 90, may be kept and used to finally correct all punches before they are hardened and tempered. The various stages of machining the cutting-out punch is shown at fig. 94, where P is a steel forging, which has been centered and had its shank truely turned, and the required shape dotted out upon the cutting end. The punch may then be placed in the special fixture seen at fig. 89, to enable the part e at P 1, fig. 94, to be milled away. This would be done with the cutter A1 ,an ordinary milling cutter. Passing to P1 21, it will be seen that the ends dt d1 have been milled away with the milling cutter B. The punch may now be carefully fitted into the standard die A, fig. 90, by means of filing.

The complete set of tools for piercing the two holes in a driving chain link are a good example of accurate tool making. These tools illustrate the application of steel bushes for accurate piercing. A bolster B, fig. 95, planed top and bottom, and having two holes, one of which is seen at X, drilled and tapped, is ready to receive the pin, fig. 100. Two such pins serve the double purpose of setting up the small piercing dies, 0, P, fig. 95, and allow the piercing bits or small blanks to drop through the long hole that is drilled through the centre of the pins for this purpose. The die holder D H receives the piercing dies O, P, which are held in position by a small set pin, seen in the part section of the die at fig. 95. The die holder D H is fastened to bolster B by four screws. The false nose or punch holder F N is made from a Bessemer steel forging, shaped out to receive steel pieces A, B, and C. These are held in position by set screws. Another thinner steel piece 1) is fitted into the punch holder, and hardened to receive the thrust from the punch ends when they are piercing blanks.