by Robert W. Lang
The mortise-and-tenon joint is fundamental in woodworking. Along with the dovetail, this joint has been used for thousands of years. If you judge by the number of devices and methods developed to avoid making mortises, you might think it difficult and demanding. In truth, a mortise is just a square hole.
As with most holes, it doesn’t really matter how you dig it. The fundamental elements are the same whether you chop by hand or mill with a machine; confusion arises because it isn’t always obvious what is important to make a sound joint in a reasonable amount of time.
A mortise isn’t any good without a matching tenon. If the joint fails it is usually because too little wood is left around the mortise, so it makes sense to let the location and size of the mortise determine the size of the tenon.
The first thing to consider is where to locate the mortise – too close to the end of a board leaves weak grain that can easily break while making the mortise, or when the finished joint is stressed.
Article: The best mortises are useless without a properly fitted tenon; read about three different techniques that use a variety of tools.
Video: Watch a mortise being chopped under glass in this video filmed at our first Woodworking in America Conference.
Blog: Read about sizing tenons to the mortise without measuring.
In Our Store: “Classic Arts & Crafts Furniture,” projects built for Popular Woodworking Magazine by Robert W. Lang.
To Buy: “Mortise & Tenon: Tools and Techniques from a Master Woodworker.”