Skill Builder: Mortise-and-Tenon Joinery

By Rockler Woodworking & Hardware

If there ever was a classic wood-to-wood joint, the mortise-and-tenon is it. Typically, its two halves are formed directly from the two members being joined with no separate components involved. These joints create strong, reliable bonds for all manner of wood furniture and cabinet assemblies.

Like the Chinese yin and yang, the two halves of a mortise-and-tenon joint are male and female: The male tenon is shaped on the end of one member (with shoulders stopping the cut) and fits snugly into the female mortise that’s chopped, drilled, or routed into the edge or face of the other member.

Mortise-and-Tenon Uses

On typical mortise-and-tenon joints, the protruding tenon fits into a squared and matching excavation in the mating part, called a mortise. Once assembled, all visible evidence of the joint is hidden.

Mortises and tenons are most commonly used for frame joinery; they’re a strong and traditional way to connect stiles and rails end to edge for frame-and-panel doors or cabinet face frames. They’re also great for attaching aprons or stretchers to the legs of a table, bench or chair, for both square and angled connections.

Sometimes an elongated tenon passes all the way through the mortised workpiece so its end extends beyond the other edge. This decorative treatment often appears on Arts & Crafts furniture.

Though less commonly used, mortise-and-tenon joints are also solid options for building picture frames and strong casework, such as chests and the carcasses for desks and dressers.

A tenon doesn’t have to be machined onto the end of one joint member; it also can be a third, separate element, bridging both workpieces and fitting into matching mortises in the parts.

There are several variations of mortise-and-tenon joints. Standard mortise-and-tenons are cut stopped or “blind,” meaning that the entire joint is hidden; through mortise-and-tenons are cut so that the end of the tenon sticks out of the bottom of the mortised member.

You can also add wedges, keys or pins to these joints to decorate and lock them together. Another option is to cut loose-tenon joints, where two mortised parts are brought together by a third separate tenon piece.

Machining Options

Tenons — the protruding portions of a mortise-and-tenon joint — are often formed at the table saw with a wide dado blade. Side-by-side cuts neatly remove the waste and establish the tenon’s thickness, width and length.

Long before power tools were the order of the day, woodworkers created these joints entirely by hand, chopping the mortise with a chisel and mallet, then sawing a tenon into the end of the mating board to fit the mortise. Of course, if you’re up for the challenge you can still build these joints like our forbears did, but there are many other machining options that can get the job done more quickly, accurately and with fewer hand-tool skills.

Accurate layout is the first step to creating a centered mortise on the edge or face of the joint’s mating workpiece.

For example, if you have a drill press and brad-point or Forstner bits, you can remove most of the material for a mortise by drilling a series of holes in a straight line, then paring away the remaining waste to create flat walls and square ends. It’s simple, even for beginners.

Here that task is being accomplished with Rockler’s Center/Offset Marking Tool.

A router outfitted with a straight bit and an edge guide is another practical option for milling mortises. A router table can make this task even easier, because the fence can be marked to set the ends of the mortise, and you don’t have to concern yourself with guiding and balancing the router over the workpiece by hand.

Then, most of a mortise’s waste can be excavated with a drill press and Forstner or brad-point bit.

Typical tenons can be cut with a standard blade or dado blade on the table saw safely and easily, using the rip fence and miter gauge or a tenoning jig to register the cuts. Some woodworkers cut tenons on the band saw instead, or you can mill tenons on a router table with straight or rabbeting bits.

What waste remains is easy to chisel away.

Festool’s Domino machine and Rockler’s Beadlock system are two popular options for creating mortises that are then fitted with “loose” prefabricated tenon stock. Once the mortises are cut, the busy work is basically done.

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  1. Great article – I’ve played around with the Rockler beadlock system on a tabletop once. It was effective and provides great alignment and a strong joint. But if you can swing it the Domino is a dream to use.