materials, when the work has been nicely done, one would scarcely notice that the blanks had been severed from the stock. This condition is taken advantage of oftentimes in clock manufacturing. Gear blanks, for instance, are punched out from strips of metal and inserted back in their places again, minus, of course, the stock which has been punched out to form the arms and the hole for the "staff" or little shaft on which it is mounted. These strips, thus prepared, are then taken to machines where the staffs are inserted and fastened, it being much easier to handle the little wheels in this way than if they were severed and handled in bulk.

Besides the advantages of permanent setting of the punch and die and the holding of the stock to prevent distortion, which allows very narrow bridges of material to be left between wide openings, the suitability of the sub-press for delicate work, such as the piercing of small holes in thick stock, will be appreciated by reference to Fig. 3. It will be noted that, no matter how small punches e and ƒ may be, no portion of their projecting ends is at any time left unsupported laterally by shedder H or by the work. The shedder, pressing down firmly on the work, supports the end of the punch at the point where the pressure is applied. It is thus possible to use a very much more slender punch for a given thickness of stock than can be used in ordinary dies.

Sub-press Die for Blanking and Forming Copper Cups. The die shown in Fig. 4 was designed to blank and form up a copper cup or capsule used in the manufacture of balance wheels for watches. The copper strip is fed into the press, which then blanks out and draws the metal into the shape shown at R, at the same time punching the center hole. Referring to the illustration, A is the base of the sub-press, B the body, C the cap, and D the plunger, all these being of cast iron machined to size. The body and base are held together by two screws E after the usual well-known manner; F is the buffer plug which receives the thrust of the press piston; G is the babbitt lining of the body B; II is the outside diameter die, held in place by four screws and two dowel-pins; H1 is the outside diameter

punch, also held in place by four screws and two dowels; I is the die for cutting out the center hole, and J is the punch for this hole. The parts H1 and I also serve as forming dies in bringing the metal to the proper shape. The "shedders" or strippers K and L are supported by four push-pins, those of the former resting upon springs, the tension of which is controlled by short threaded plugs, as shown, and those for the latter

Fig. 4. Sub-press for Blanking, Piercing and Drawing the Copper Cup shown at R

abutting against the piston M, which is pressed down by the large spring N, the tension of which is controlled by the plug O. The block P is used merely to hold the punch J firmly in place.

The operation of the die is as follows: The press ram being at the top stroke, the copper strip is fed in across the top of H, and as the ram descends, the blank is cut from the strip by the punch

H1 and drawn to a cup shape between the inside edge of H1 and the outside edge of I. Simultaneously, the center hole is punched by J and I. As will be seen by referring to the illustration, J is made a trifle short, so that the drawing operation will have begun before this hole is punched; this prevents any distortion of the piece by the punch J. A little trouble was experienced with this tool at first, on account of the air in the hollow plunger D forming a cushion when it was compressed by the rising of the piston M, thus preventing the proper working of the die. This was finally obviated by making a small groove at the side of the piston where it worked in the plug O, and drilling a vent hole through O as shown. This allowed free communication to the

atmosphere, and from then on the die gave complete satisfaction. The variation in size among the cups, or capsules, as they are called, is never more than 0.001 of an inch either in diameter or in length.

Large Sub-press Dies. The sub-press construction is employed for many large dies, as well as for those used in the production of small delicate work, although in their arrangement the larger sizes differ from those previously referred to. The circular type, which is commonly used for small work, is shown in the foreground of Fig. 5, whereas larger sizes may be seen at the left and rear. The die at the left has a plunger of rectangular shape. This operates in a bearing lined with babbitt metal, the same as the cylindrical form, although the bearing is not ad

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justable. The larger sub-press seen at the rear of the small plunger type has a sliding head or upper die which is guided by four vertical posts, carefully ground and lapped to fit cast-iron bushings. This is a construction commonly used on heavy work. The same advantages that obtain in the use of smaller

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Fig. 6. Sectional Die which Operates on Sub-press Principle ·sub-presses result from the larger sizes; that is, there is a saving of time in setting up the tools; there is a greater possibility of punching small holes in thick stock and of leaving narrow bridges of metal between openings of considerable area; the dies, owing to their accurate and permanent alignment, may be

fitted to each other much more closely and produce parts that conform to the required dimensions within small limits.

Sectional Sub-press Die. A sectional or built-up die, which is built on the sub-press principle, is shown in Fig. 6 and the punch (which is the lower member) is illustrated in Fig. 7.

The plan view of the punch also indicates the irregular shape of the blank which is produced. The die is so constructed that the blanks can be changed to different shapes by simply inserting different die sections in different places of the die. At A, ́ Fig. 8, is shown a modification of the blank, possible with this die. Another of the principal features of this sub-press sec