A hammer is a striking tool consisting of a weighted head mounted on a handle, used for driving nails, shaping metal, and general striking work. The hammer is one of the oldest and most fundamental hand tools.
The claw hammer is the most common hammer in general construction and woodworking. It has a striking face on one side of the head and a claw on the other for pulling nails.
The curved claw hammer has a claw shaped in a gentle arc. The curve provides leverage for pulling nails. The face may be smooth (for finish work) or milled (for framing).
The rip claw (or straight claw) has a straight, notched claw that functions as a pry bar for ripping apart nailed assemblies. Common in framing, the rip claw can also pull nails from the side.
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Smooth-face hammers are preferred for finish carpentry because they leave fewer marks on the wood. Milled-face hammers (also called checkered) reduce the chance of the hammer slipping off the nail head.
A framing hammer has a longer handle (40–50 cm / 16–20 in) and a heavier head (680–900 g / 24–32 oz) than a standard claw hammer. The milled face is designed for aggressive nail driving in rough construction.
A ball-peen hammer has a rounded face (the ball) on one side and a flat striking face on the other. It is primarily a metalworking tool.
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The ball end is also used for peening (work-hardening) metal surfaces and for shaping sheet metal.
A tack hammer has a split head or a magnetic head designed for holding and driving small nails and tacks. One face is magnetic, the other is flat. They are used in upholstery, carpeting, and light woodworking.
A mallet is a hammer with a non-metallic head, used for striking chisels, assembling wood joints, and forming soft metals. Types include:
The hammer should be gripped near the end of the handle for maximum leverage. The wrist snap at the point of impact drives the nail. For heavy driving, the arm and shoulder are used in addition to the wrist. For finish work, the hammer is choked up on the handle for control. The hammer face should strike the nail head squarely to avoid glancing blows and bent nails.
The user should wear eye protection against flying metal fragments. The hammer head should be checked regularly for looseness. A loose head can detach mid-swing. Cracked or splintered handles should be replaced immediately. Never strike a hardened steel object (such as another hammer) with a claw hammer — hardened fragments can chip off at high velocity.