Steel woodworking chisel.
A chisel is a tool with a characteristically shaped cutting edge (such that wood chisels have lent part of their name to a particular grind) of blade on its end, for carving and/or cutting a hard material such as wood, stone, or metal. The handle and
blade of some types of chisel are made of metal or wood with a sharp edge in it.
In use, the chisel is forced into the material to cut the material. The driving force may be manually applied or applied using
a mallet or hammer. In industrial use, a hydraulic ram or falling weight ('trip hammer') drives the chisel
into the material to be cut.
A gouge, one type of chisel, is used, particularly in woodworking, woodturning and sculpture, to carve small pieces from the material. Gouges are most often used in creating concave surfaces. A
gouge typically has a 'U'-shaped cross-section.
Types
Chisels have a wide variety of uses. Many types of chisels have been devised, each specially suited to its intended use.
Different types of chisels may be constructed quite differently, in terms of blade width or length, as well as shape and hardness
of blade. They may have wooden handles attached or may be made entirely of one piece of metal.
Woodworking chisels
Woodworking chisels range from quite small hand tools for tiny details, to large chisels used remove big sections of wood, in
'roughing out' the shape of a pattern or design. Typically, in woodcarving, one starts with a larger tool, and gradually
progresses to smaller tools to finish the detail. One of the largest types of chisel is the slick, used in timber frame construction and wooden shipbuilding. According to their function there are many names given to woodworking
chisels, such as:
- butt chisel: short chisel with beveled sides and straight edge for creating joints.
- carving chisels: used for intricate designs and sculpting; cutting edges are many; such as gouge, skew, parting, straight, paring, and V-groove.
- corner chisel: resembles a punch and has an L-shaped cutting edge. Cleans out square holes, mortises and corners with
90 degree angles.
- flooring chisel: cuts and lifts flooring materials for removal and repair; ideal for tongue-and-groove flooring.
- framing chisel: usually used with mallet; similar to a butt chisel, except it has a
longer, slightly flexible blade.
- slick: a large chisel driven by manual pressure, never struck.
- mortise chisel: thick, rigid blade with straight cutting edge and square sides to make mortises and similar joints.
- paring chisel: has a long blade which is ideal for cleaning grooves and accessing tight spaces.
- skew chisel: has a 60 degree cutting angle and is used for trimming and finishing.
Lathe tools
A lathe tool can be a woodworking chisel designed to cut wood as it is spun on a lathe. These
tools have longer handles for more leverage, needed to counteract the tendency of the tool to react to the downward force of the
spinning wood being cut or carved. In addition, the angle and method of sharpening is different, a secondary bevel would not be
ground on the tool.
Metalworking chisels
Chisels used in metal work can be divided into two main categories, hot chisels, and cold chisels. A hot chisel
is used to cut metal that has been heated in a forge to soften the metal.
Cold chisel
A cold chisel is a tool made of tempered steel used for cutting 'cold' metals,
meaning that they are not used in conjunction with heating torches, forges, etc. Cold chisels are used to remove waste metal when
a very smoothfinish is not required or when the work cannot be easily carried out with other tools such as a hacksaw, fgile,
bencch shears or power tools.
The name cold chisel comes from its use by blacksmiths to cut metal while it was cold as compared to other tools they used to
cut hot metal. This tool is also commonly referred to by the misnomer 'coal chisel'. Because
cold chisels are used to form metal, they have a less-acute angle to the sharp portion of the blade than a woodworking chisel.
This gives the cutting edge greater strength at the expense of sharpness.
Cold chisels come in a variety of sizes, from fine engraving tools that are tapped with very light hammers, to massive tools
that are driven with sledgehammers. Cold chisles are forged to shape and hardened and
tempered (to a brown colour) at the cutting edge.
The head of the chisel is chamefered to slow down the formation of the mushroom shape caused by hammering and is left soft to
withstand hammer blows.
The are four common types of cold chisel. These are the flat chisel, the most widely known type, which is used to cut bars and
rods to reduce surfaces and to cut sheet metal which is too thick or difficult to cut with snips. The cross cut chisel is used
for cutting grooves and slots. The blade narrows behind the cutting edge to provide clearance. The round nose chisel is used for
cutting semi-circular grooves for oil ways in bearings. The diamond point chisel is used for cleaning out corners or difficult
places and pulling over centre punch marks wrongly placed for drilling. Although the vast majority of cold chisels are made of
steel, a few are manufactured from beryllium copper, for use in special situations
where non-sparking tools are required.
Hardy chisel
A hardy chisel is a type of hot chisel with a square shank, which is held in place with
the cutting edge facing upwards by placing it in an anvil's Hardy
hole. The hot workpiece cut is then placed over the hardy, and struck with a hammer. The hammer drives the chisel into the
hot metal, allowing it to be snapped off with a pair of tongs.
Stone chisels
Stone chisels are used to carve or cut stone, bricks or concrete slabs. To cut, as opposed to carve, a brick bolster is used;
this has a wide, flat blade that is tapped along the cut line to produce a groove, then hit hard in the centre to crack the
stone. To increase the force, stone chisels are often hit with club hammers, a heavier type
of hammer.
Masonry chisels
Masonry chisels are typically heavy, with a relatively dull head that wedges and breaks, rather than cuts. Normally used as a
demolition tool, they may be mounted on a hammer-drill, jack
hammer, or hammered manually, usually with a heavy hammer of three pounds or more.
Plugging chisel
A Plugging chisel has a tapered edge for cleaning out hardened mortar. The
chisel is held with one hand and struck with a hammer. The direction of the taper in the blade determines if the chisel cuts deep
or runs shallow along the joint.
See also
External links
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