Page:Popular Science Monthly Volume 92.djvu/148

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��Popular Science Monthly

��wards. When this is done the die is removed and the core drilled out. A flat chisel as shown set E is necessary to break the web left from the drilling of the core. Do not drill the holes too close to the die line, for a cut over the outline will make it necessary to use a put- ting-on tool. It is easier to remove the stock by filing than to hammer the steel to fill the space.

The die being small it is not necessary to use a milling machine for finish- ing. The finishing is done by chiseling off most of the web and then filing to the lines. When this point is reached and the proper clearance is made, the die is again placed in thq shaper and a cut taken on both sides of the die as at F. This is to make the clamp hold and to prevent the die from lifting out of the bolster. In case of mishaps necessitating regrinding, the die should be cut away as at G, which saves time. A

���The finished die and ready for the power

��in. IS

��depth of j sufficient. Four holes are now drilled and tapped as shown for M-in. screws having 24 threads to the inch. Two holes are also drilled for dowel pins.

Do not forget that there must be a stop for the material after it is blanked. For this purpose a hole is drilled at H and a pin driven in and bent over.

Die makers are not always permitted to do their own hardening, but should this be a

���fifj 4 tND VltW OF PUNCH

Plan of the punch 'and manner of cutting the metal away to make the proper shape

part of your work proceed as follows: Fill up the drilled holes with fire clay to prevent any possible stresses or cracking. After ascertaining what kind of steel you have, and the treatment required, heat it to

��the proper temperature, or color, and queno.h it quickly in water or oil. After hardening the surface of the die, clean it and replace it in the furnace to bring it to a dark straw color, or 460 deg. F. The die is now ready for use in making the punch, which is shaped from a round piece of steel 1 3-2 in. in diameter. A piece of the steel is cut to the right length; the ends are centered, put in a lathe and turned down, as shown in Fig. 4, to the size neces- sary to fit the punch holder for the press work. When this is done, brighten the large end and apply the blue stone solution; clamp the end in a vise and lay the die upon it. Transfer the outline of the die with the scriber.

Next, take the piece to the milling machine and clamp it in the chuck of the index head or between centers. Mill all around and up close to the line scribed, as shown in the end view. Then re- move it from the chuck and file it so that the punch will just about enter the die; now adjust it in the press as if for use with the already made and hardened die, and "shear it." Care must be taken to see that the die will remove some metal from all sides. When located properly, force the punch into the die. If too much material has been left on the punch, do not attempt to force it through, but remove again and file to mark obtained by this operation. To insure a good, smooth finish as little material as possible should be left to shear.

The punch is hardened in the same manner as the die and the cutting edge is ground sharp. To complete the job we must now make the stripper plate. A piece of machine steel of about } ^ in. thickness, as shown in Fig. 5, is clamped on the die and holes are drilled to coincide with the hole of the die. After the plate is secured to the die the outline of the blank is scribed on the stripper plate in the same manner as on the punch. The core on this plate is drilled out in the same way as for the die. It is filed close to the lines; and punch and die are set on the press again. When

��punch press

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