The hammer is the universal tool. Be it car or boat repair, removing concrete, building a house and even hanging a picture, the hammer comes into play. There are claw hammers, ball-peen hammers, mallets, tack hammers, framing hammers, finish hammers, sledgehammers, rigging axes and more. And most are available in an assortment of sizes.
Although a hammer is primarily for nailing, a blacksmith would probably tell you that that use is secondary in his work, and a concrete laborer surely will advise that there is no nailing involved in the removal of concrete.
The weight of a hammer is important to someone like a carpenter who frequently uses one all day long. It must be light enough to swing briskly, and yet heavy enough to provide sufficient force to drive a nail with a minimum of blows. For example: most carpenters who assemble wood-frame structures like to drive a 16d nail (about 3 inches long) in one or two blows. Carpenters are careful to get a hammer that is heavy enough to accomplish this, yet light enough to avoid wrist or elbow damage - something that a heavy hammer is known to cause.
Whereas hammers used for framing and siding range from 20 oz. to 28 oz., finish hammers weigh between 12 oz. and 20 oz. The most common hammer is the 16-oz. curved-claw finish variety.
A hammer can be broken down into two component parts: the head (the face and the claw) and the handle. The face is the part that comes into contact with the nail - and there are a few important things to know about this. First, there are two face types - smooth and corrugated. The smooth is designed for fine finish work, and the corrugated face is for rough framing. It is safer to use the corrugated head because it grips the nail tightly and reduces the chance of bending nails. Unfortunately, the same corrugation that grips the nail also can leave a waffle mark in the surface of the wood. So, for fine work (and no waffle marks) the smooth-face version is better. However, there is a trick you should know about this hammer. Even the slightest increase in surface roughness can improve friction and reduce nail bending. Old-time finish carpenters rub their hammer face on a sidewalk. The concrete removes the shine from the face of the hammer and creates enough roughness to reduce nail-bending. A good finish carpenter never drives a finish nail all the way in with a hammer. The final blows are struck with a nail punch.
There are two basic types of claws, curved and straight. The curved claw provides more leverage and makes nail-pulling easier. Also, the curved-claw hammer can be used in tighter spaces than the straight-claw type. The overall length of the head is reduced by the curve of the claw. This can make all the difference in the world to a carpenter who is installing a 12-inch-deep wall cabinet where backswing is minimal. So why the straight claw? In certain tasks it is the only type that can be used to remove a nail. A curved claw is safer during the backswing than is a straight claw.
Most folks would agree that a wood handle is the most desirable type. With all the modern technology available, the oldest material known to have been used for a hammer handle still is considered the best. The material of which the handle is made is important to the user. Much of the shock transferred from the hammer's impact is absorbed by the handle. With a solid-steel handle, most of the shock would be absorbed by your hand, wrist, forearm and elbow. Manufacturers are doing wonders with fiberglass and plastic, but, in our opinion, wood still tops the list.
A safety note for anyone who likes to build things: The face of a good hammer is tempered (hardened steel). The hardening prevents the hammer face from losing its shape as it is being used. The hardening process actually makes the face of the hammer brittle. In fact, when one hammer face strikes another, tiny pieces of the brittle face will break off and fly through the air at high speed. During our days in carpentry, we saw a fellow put his eye out. He wasn't even working, just banging two hammer faces together and joking around.
Another safety precaution: A rigging ax has a large corrugated face with an ax in place of the claws, and a long handle. Don't use this tool for carpentry. It can be dangerous because the backswing can cause a severe wound. Also, never sharpen the claws on your hammer. It might facilitate the removal of nails, but would, in the process, convert a valuable tool into a dangerous weapon.
