When making a hammer the stock should be taken large enough to make the largest part of the hammer without any upsetting. As a general rule the hammer is forged on the end of a bar and is finished as completely as possible before cutting off. Riveting Hammer. About the easiest hammer to shape is the riveting hammer shown at D, Fig. 8. This hammer, as well as all other hammers, is started by first punching the hole for the eye as shown at A, Fig. 139. When the eye is punched the stock is generally bulged out sideways, and, in order to hold the shape of the eye while flattening down this bulge, a drift pin such as shown in Fig. 140 is used. This pin is made larger in the center and tapering at both ends. The center or larger part of the pin has the same shape as the finished eye of the hammer. This pin is driven into the punched hole and the sides of the eye forged into shape, as illustrated at B, Fig. 139. After the eye has been properly shaped, the next step is to shape down the tapering peen leaving the work, after a nick has been made around the bar where the face of the hammer will come, as shown at C. The end of the hammer toward the face is then slightly tapered in the manner indicated at D. After the hammer has been as nearly as possible finished, it is cut from the bar and the face trued up. For tempering, the whole hammer is heated to an even hardening heat. The hammer is then grasped by placing one jaw of the tongs through the eye. Both ends are tempered, this being done by hardening first one end and then the other. The small end is first hardened by dipping in the water as shown at Fig. 141. As soon as this end is cooled the position of the hammer is instantly reversed and the face end hardened. While the large end is in the water the smaller end is polished and the temper color watched for. When a dark brown scale appears on the small end the hammer is again reversed bringing the large end uppermost and the peen in the water. The face end is then polished and the temper drawn. If the large end is properly hardened before the temper color appears on the small end, the hammer may be taken completely out of the water, the large end polished, and the colors watched for on both ends at once. As soon as one end shows the proper color it is promptly dipped in water, the other end following as soon as the color appears there; the eye should never be cooled while still red hot. For some work hammer faces should be left harder, but for ordinary use the temper as given above, is very satisfactory. Ball-Peen Hammer. The general method of making a hammer of this kind is illustrated in Fig. 142. Starting with round stock (carbon steel), flatten under a power hammer, if one is available, as at A; otherwise use a set hammer on an anvil in the same manner, and then work enough down for the ball peen, as shown at B. Then fullers are used as at C, to space off for the hole to be punched between the octagonal parts formed with the fullers. To keep from flattening the part through which the hole is punched, it should be placed on a bottom fuller of the proper size. Care should be taken not to heat the steel too hot for this operation, as heat cracks are sure to take place. The steel should be of fairly high carbon; not less than 1 per cent. Harden and temper to about dark straw color, or 430° Fahrenheit.
Fig. 139. Method of Making Hammer.
Fig. 140. Drift Pin.
Fig. 142. Method of Making Ball-Peen Hammer.