A nail set, sometimes called a nail punch, is a special tool made of hardened metal, usually steel, that's used drive the head of a finishing nail flush with or beneath a work surface. A nail set may sometimes be used as a punch, creating a small hole, or dimple, in wood as a guide for driving a nail. Nail sets generally aren't used for construction work like framing a house, but are extremely useful when doing finishing work, such as installing moldings, baseboards and other trim, both interior and exterior.
Nail sets are usually sold singly, but they're also available in sets of three to five different sizes. A standard set of three should be sufficient to deal with most commonly used sizes of finishing nails. Generally between 4 and 6 inches (10 to 15 centimeters) long, a nail set has two parts: the handle and the tip. The handle, rarely thicker than a standard screwdriver handle, is 1/2 to 2/3 the length of the tool. A nail set's tip is tapered from the handle to a point narrow enough to fit on the head of a finishing nail. Different manufacturers sometimes add various features to enhance the appearance or value of these tools. Most, for instance, are completely metal, with ridges or crosshatches embossed into their handles to prevent the tool from slipping. Some are manufactured with rubber or plastic grips installed over the handles for comfort and also to reduce or prevent slipping.
Nail sets are most commonly used in finishing work. Molding and other trim work is fastened to walls or ceilings with finishing nails: relatively short, thin wire nails with heads only slightly wider than the nail's diameter. These are hammered through the molding to fasten it to the wall or ceiling, leaving the head of the nail just barely proud of the surface — that is, just slightly protruding. Then, the tip of a nail set is placed in a dimple in the nail's head made for that purpose, and the nail set is struck with the hammer once or twice to drive the head of the nail flush with or below the surface of the wood, “setting” it. If the nail head has been driven below the wood's surface, the small hole left is filled with an appropriate putty and allowed to dry before it is lightly sanded and finish is applied to the molding.
Most nail sets are a single piece of metal, but some are more elaborate. One popular nail set has a hole in its center that extends the length its body, and contains a spring-loaded pin that protrudes through the hole out the back of the nail set. The hole is placed over the nail head, and the user strikes the protruding pin with a hammer, driving the pin forward, hitting the nail head and recessing it into the wood's surface. The benefit of this type of nail set is that the pin that strikes the nail has no chance to slip off and mar the wood's surface, which is sometimes a problem with one-piece nail sets.