Locate the center of the 21⁄2-inch length; from that point place a center-punch mark 7⁄8 inch each side of the center and punch a 5⁄16-inch hole at each mark with a hand punch, by placing the outer edge of the punch at the center-punch mark. Deliver no blows on the edges of this metal after the holes are punched.
Using a sharp, hot cutter, remove the metal between the holes, by cutting it equally from both sides, thus forming the slot as indicated by the broken lines in sketch E. By placing it over the hardy, straighten the metal which forms the sides of this slot, and all other portions, so that all edges will be straight and parallel to each other. Smooth all flat surfaces with a flatter, using water to remove the scale of oxide. If the marking and punching of the holes have been carefully done, the inside length of the slot will now be 2 inches.
Bend the 21⁄8-inch end to a right angle at the shoulders, having the length from the inside of the angle to the outside of the eye about 7 inches. Heat this entire end and quickly cool the extreme corner of the angle to prevent its straightening there, then form the hook to the dimensions given in sketch F. The inner edges of the slot may be filed straight and parallel to the outside edges, but the semicircular ends which have been formed by the punch should not be disturbed.
74. Hexagonal Head Bolt.—Fig 54. Upsetting and forging to a hexagonal cross section. Material required: 7 inches of 1⁄2-inch round iron.
Heat one end to a white heat, then cool off 41⁄2 inches of the opposite end, thus confining the upsetting to the required area; upset the hot end until its diameter is 3⁄4 inch, and the length over all is about 51⁄2 inches.
It is important that the 41⁄2 inches be kept perfectly cold, to prevent upsetting there, also to prevent its sticking fast in the heading tool, or possibly using more metal than is required for forming the head.
Fig. 54.—Hexagonal Head Bolt.
The upset metal should extend equally around the bolt. This will tend to prevent the head from forming unequally when the metal is being forged down on the heading tool. The head can be prevented from forming on one side by directing the blows toward the opposite side. Form the head by heating the upset end to a white heat, by inserting the opposite end in the heading tool, and by delivering upright blows on the heated end, unless others are required, thus forging down the upset metal to 1⁄2 inch thick. Remove it from the heading tool and forge the head into a hexagonal form. It will be necessary to insert the bolt in the heading tool several times to obtain the exact dimensions of the head, which should be 7⁄8 inch through its short diameter and 1⁄2 inch thick. The chamfered finish on the top of the head is produced by using a button head set while the bolt is held in the heading tool.