Cold chisels aren’t for cold weather; they’re for cutting cold, hard metal. A cold chisel will cut any metal that is softer than the material from which the chisel itself is made. Made of hardened steel, cold chisels have a beveled cutting edge and an octagon-shaped handle. The cold chisel has a flat cutting edge, but related chisels are wedge-shaped (cape chisel), half-round, diamond-shaped, or round.
Cold chisels are used to cut rivets, to split nuts or bolts that refuse to come loose, or to break castings. They can also be used to cut sheet metal. The metal chisels with edges in other shapes have other applications, such as grooving or shaping corners.
Don’t use a cold chisel to cut masonry; there are specially made tools for that purpose.
To use a cold chisel, select a hammer of suitable weight, usually a ball peen or club hammer. The bigger the chisel, the heavier the hammer that is needed, because a large chisel will absorb much of the force of a light hammer blow and do little or no cutting.
Find your safety glasses or goggles, too, and wear them whenever you are cutting with a cold chisel. Shrapnel-like chips are an occupational hazard.
Grasp the handle of the chisel, making a fist around its handle with your thumb and forefinger an inch or so from the top. Hold it securely but not tightly. A too-rigid grip will transfer much of the force from the hammer blows to your hand and arm, leaving them ringing with the shock of the blow.
Don’t try to do all the cutting with single blows, but swing the hammer in a controlled rhythm. Watch the cutting edge of the chisel, not the handle.
Brick Chisel. Also called a bolster or brick set, the brick chisel is used to make smooth cuts on bricks. Rough cutting of brick is usually done with a brick hammer (which has a chisel-like blade opposite the face of the hammer).
Cutting a brick with a brick set isn’t complicated. Position the chisel perpendicular to the brick, with the straight side of the cutting edge facing the end of the brick to be used. Strike the handle of the chisel with a small sledge or club hammer, hard enough to score the brick but not to shatter it. Score the brick on all sides, then strike it once more to break the brick in two.
Brick chisels should not be used for cutting stone, as they will quickly lose their edge.
Masonry Chisels. Some masonry chisels are designed for cutting soft stone, while others will stand up to harder use.
Like brick chisels, masonry chisels are generally used only to score the stone; as with glass cutting, the task involves scoring first, then breaking along the score line. Gentle taps on the chisel create the score line, allowing the stone to be snapped off when the line has been completed.
Floor chisels are another variety of chisel that can be used to scrape floors, clear off blobs of concrete, and other rough chisel work.