A tin hammer is used to hammer all classes of gun-metal, iron, and steel work which is smoothly finished and must not be bruised or disfigured with hammering, which would be the result if ordinary hammers were used. A tin hammer supersedes the use of a hollow drift, if the end of the pin to be hammered protrudes a sufficient distance to receive the blows ; if not, a drift is necessary to reach the pin, which is then dislodged with hammering the drift. Tin hammers are of various sizes to suit all classes of work, and are provided with ordinary ash handles similar to those for other hammers. Fig. 424 indicates an ordinary shape for tin hammers, the whole class being useful while fitting and dislodging pins, bolts, keys, slides, guides, rods, levers, and a large quantity of other engine and machine work of all descriptions. Another class of hammers for similar purposes are those made of copper; these are only available for hammering iron and steel, copper being too hard for gun-metal. Brass, which is much softer than gun-metal, must be hammered with wood hammers or with ash-wood drifts. For a great variety of small work, an iron drift having a thick leather face attached to one end is very useful.