A corner chisel is one of the most commonly used chisels, mainly because it can easily be used to remove any excess material from a corner cut in a mortise joint. It can also be used to clean the edges of a dovetail cut. This is mainly because of its shape.
Woodworking tools, especially hand tools, come in hundreds of different shapes and sizes, all with a number of different uses. For chisels, this is especially true because they are used for a variety of applications. The main function of a chisel is to remove material in a manner determined by the shape of the chisel tip. Unwanted materials are removed by driving the chisel tip down at an angle into the work piece and pushing the chisel in the direction of the desired material removal.
A corner chisel has a squared head, sometimes with a concave indentation in the tip so it can cut squared corners into mortises. This is the most common use of the corner chisel. The hand tool is used in multiple woodworking applications because of its ease of use when properly maintained.
Proper maintenance means ensuring the tip and edges of the chisel blank are kept filed and sharpened. The blank of the chisel usually runs directly into the handle, which is typically made out of wood in early or traditional models. Newer corner chisels often have softened composite handles to allow for repetitive use without hand damage. The tip of the corner chisel is most commonly made of steel because of steel's ability to keep its edge through multiple uses and because steel can generally withstand the conditions of a productive woodworking shop.
New corner chisels are shaped a bit differently than the traditional corner chisel. Most often, they are in two parts, one of which is a machined blade shaped at a right angle and attached with machined screws to the jig handle. The handle is long enough that it can be held with one hand while in position and hit with a hammer or mallet, simplifying the process of chiseling out a precise mortise for a door on the jamb side with a simple hammer strike. This makes the process of cutting door mortises much easier than the use of an older model hand chisel, which usually requires the task to be completed in thin layers.