It is interesting to trace the process of making a die and punch to a standard pattern, such for instance as the two ordinary shapes, a pedal plate blank, fig. 83, and a spanner blank, fig. 84, the die D having been planed or milled both on the top and bottom and the necessary angle planed upon its sides to fit the bolster. The top of the die should now be cleaned off with a smooth file and emery cloth, after which the top must be smeared with sulphate of copper,

Fig. 83.

Fig. 84.

7WP commonly known in the workshop as"blue stone."This is done to enable a fine line to be seen, for without tin-blue stone, it would be of little use marking out a shape upon the bright face of the steel die with a marking scriber, because the lines could only be traced by the eye with great difficulty. In some instances the standard blank would bo used as a template to mark out the shape upon the die, but this is not considered a good method unless a perfectly accurate blank is used as the template. Assuming that the blank is one that has been cut by a pair of ordinary press tools, probably it would not be accurate, therefore the better plan would be for the tool maker to carefully set out and mark the shape accurately upon the face of the die. This would be done with square, compasses, and scriber, in a similar manner that a detail drawing would be made upon a piece of drawing paper. From this it follows that a knowledge of geometrical drawing is very useful to the tool maker. Having carefully indicated the outline of the figure by dots from a small centre punch, as much of the metal as possible should be removed by drilling various sized holes straight through the die; the size of the drills used will depend upon the size and shape of the hole required in the die-in other words the size and shape of the required blank. After removing as much metal as is possible by drilling, the die may be turned over and larger drills passed up the back to a certain depth, thereby forming a clearance; this clearance will be seen in the section at h.

If the holes have been carefully set out to follow the outline of the shape a little chipping with a thin flat chisel on top and bottom of the die will remove the bulk of the metal in one piece or lump. The back or clearance side of the die may now be cut away by the aid of larger chisels, after which the die is turned over in the vice so that the top, showing the outline of the figure, faces the operator, who will carefully chip and file out the shape of the blank by using the various small chisels and files. When the shape is apparently filed up true to the line, assuming that the pattern blank, fig. 85, is a true one, it is usual to try the blink upon the die, filing away the die until the pattern blank will pass into the hole. Suppose this has been done, and when the pattern is in the die and b1 in blank comes to b in die, E1 to E, and f1 to f; now either turn the blank completely over, so that a comes to b, b1 to a, then E1 will still be by E, as will also f1 to f. This will show up the imperfection of shape in the curves of the die, and is known as correcting the die. Should the pattern blank pass into the hole and fit fairly well, showing no spaces when held up to the light, both when the blank has been passed in one way then the other, the blank and the die would be considered sufficiently true for ordinary work; but if still greater accuracy is required the blank may be turned or swivelled round half a revolution, bringing E1 to f, and f1 to E, as this will give an additional test for accuracy. It is unnecessary to trace the making of the die, fig. 84, as that would be made in the same manner as fig. 83. One point, however, may be mentioned regarding fig. 84, namely: In the case of testing the die for accuracy the shape of spanner blank, fig. 86, would not allow the test of turning end for end, consequently the blank would merely be turned over, and tried in the hole of the die fig. 84. If the shape of the figure upon the die had been copied from a drawing or sketch, as would have been the case supposing there had been no pattern blank to work from, the mechanic who is responsible for making the die may either set out and file a template of sheet-iron, steel, or brass, or he may place a piece of sheet bad on the die, tap it all over carefully with a small hammer, when it will be seen that the shape of the hole is formed upon the sheet lead. Now carefully cut round the lead with a penknife, thereby producing a sheet-lead template or pattern, finally hammering the piece of lead straight through the die; then turn the end for end, or over, as the case may permit, and try into the hole again in the manner before explained. The sheet lead method of testing dies is very useful, as by a little practice and care much time may be saved when a large variety of shapes and small dies are to be made-time that would otherwise be taken up in making metal templates from iron, steel, or brass. Having made the die it may now be hardened and tempered, and attention may now be turned to the making of the punches, figs. 87 and 88; the punches will be centred on their faces at A A1, and centred at their shank ends. The shanks should be turned to some standard size, and the top and bottom faces turned or faced perfectly flat whilst they are in the lathe, and sulphate of copper smeared over the bottom face and the outline of the figure marked out with the scriber, using either the iron, steel, brass, or sheet-lead blank as a template. The punch may now have a groove planed or chipped all round (see figs. 87 and 88 at C). This will give a clearance so that the punch may be fixed upon the shaping machine in a special fixture (see fig. 89), and shaped up by the tool T; this will enable the bulk of the metal to be removed. The punch may next be carefully filed up to the lines marked upon the face, and finally driven into the die about 1/16 in., which will produce the required shape on the end of the punch. The punch can then be put back again into the fixture, fig. 89, and carefully re-shaped, afterwards being filed until the punch passes into the die as freely as the nature of the work requires. The fixture for holding the punch upon the shaping machine, as seen at fig. 89, may be made in a variety of forms to suit the various requirements. The simple cast-iron fixture, fig. 89, is easily made and suits ordinary work if the shanks of punches are all made to some standard diameter. The hole H and the slot S, enable a certain amount of spring or closing of the hole to be obtained, when the pin.is screwed into the lug I2. The pin passes through lug ll, and screws into lug l2: the washer W is placed between the two lugs to prevent too much strain being put upon the lugs which might perhaps cause a break. This washer should be made of such thickness that it is just sufficiently free between the lugs to allow the shank of the punch to be gripped firmly.

Fig. 85.

Fig. 86.

Fig. 87.

Pig. 88.

Fig. 89.