What Is a Mortise Chisel?

A mortise chisel is a specialized woodworking tool designed for cutting precise, square holes—mortises—into timber. Its robust, thick blade withstands mallet strikes, while its sharp edges ensure clean cuts. Perfect for joinery, it's a craftsman's ally in creating strong, interlocking furniture joints. Intrigued by the art of mortising? Discover how this tool can elevate your woodworking projects.
Sonal Panse
Sonal Panse

A mortise chisel is a woodworking implement that is used for cutting mortise joints, the strong joints that are commonly used to build furniture. These chisels have long, stout, square blades that are capable of making both deep and shallow cuts. The chisel usually has a wooden handle, the popular choices being ash or beech, and this wooden handle is reinforced by a metal base ring. Being reinforced with metal in this manner, the reinforced wooden handle can withstand strong blows from a mallet without cracking.

There are different types of mortise chisels and these are available in different sizes as well. A carpenter's chisel set would typically contain a range of tools that could be used for varying purposes. For instance, the heavy chisel that is commonly known as a "pig sticker" would be used to make the deep cuts. Using a heavy chisel first can really save both time and effort. A chisel bit fitted in a drill can also be used to make the deep cut faster. Later a lighter weight chisel, such as a sash mortise chisel, may be used to fine tune the cut by hand.

The most commonly used sizes of mortise chisels are the 1/4 inch (0.64 cm and 3/8 inch (0.95 cm) chisels. Some people make do with using just the 1/4 inch (0.634 cm) one. The 1/2 inch (1.27 cm) size is useful for cutting thick wood stock.

Man with a drill
Man with a drill

To cut a mortising joint, the lines of the mortise are first marked with a marking knife on the wood. A mortise gauge, which is a marking gauge usually made of hardwood, is then used to mark out the mortise more clearly. Once this has been done, a mortise chisel is used to chisel out the wood. The chisel is driven into the wood with strategic hammering with a mallet.

Mortise chisels need to be maintained in good condition to keep them performing well. It is necessary to keep an eye out for any signs of gathering rust, and the mortise blades will also need to be resharpened from time to time. There may be an issue of the wooden handles splitting from repeated mallet blows.

Getting high quality chisels in the first place, is ideal. It will help to research the market for the available brands of mortise chisels and find out how useful these have been found by other woodworkers.

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Discussion Comments


How important is it to have a variety of bevel angles? That is, 30 degrees is the most common, but I know there are some that are slightly more or less, like 25 degrees. What is the use/importance of this and others?

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      Man with a drill