The complete guide to mortise and tenon joint types

Are you a woodworking enthusiast looking to create durable and elegant wooden furniture pieces? If so, understanding the mortise and tenon joint is essential. This traditional woodworking joint is renowned for its strength and beauty. In this comprehensive guide, we will walk you through everything you need to know about mortise and tenon joints. From its historical roots to its practical applications in modern woodworking, we will delve into the intricacies of this classic technique. We will explain the different types of mortise and tenon joints, including through, blind, and wedged variations, and provide step-by-step instructions on how to create each one. Additionally, we will discuss the tools and techniques required for mastering this joinery method, offering expert tips and tricks along the way. Whether you are a beginner or an experienced woodworker, this guide will equip you with the knowledge and skills to create long-lasting, visually appealing woodwork with mortise and tenon joints.

Advantages of using mortise and tenon joints

Mortise and tenon joints are a time-honored and highly versatile woodworking technique that offer numerous advantages over other types of woodworking joints. One of the primary benefits of this joint is its exceptional strength and durability. The interlocking design of the mortise and tenon creates a robust connection that can withstand significant stress and weight, making it an ideal choice for furniture, cabinetry, and other heavy-duty woodworking projects. Another key advantage of mortise and tenon joints is their ability to create clean, seamless connections that enhance the overall aesthetic of a piece. The flush fit between the mortise and tenon creates a smooth, unified surface, allowing for a sleek and refined appearance that is often difficult to achieve with other joinery methods. This makes mortise and tenon joints particularly well-suited for fine woodworking and furniture-making, where the visual appeal of the finished product is of utmost importance. Furthermore, mortise and tenon joints offer a high degree of flexibility in terms of design and customization. The size, shape, and orientation of the mortise and tenon can be tailored to suit the specific requirements of a project, allowing woodworkers to create unique and visually striking pieces. This versatility also extends to the ability to incorporate additional features, such as wedges or pegs, to further strengthen the joint and add decorative elements to the final design. Mortise and Tenon joints are an extremely old construction technique that has stood the test of time and is still being used today. You can find examples of this ancient joint even in Egyptian furniture thousands of years old. Tenon is an old-time name for a square piece of wood that sticks out from the end of a board, and the mortise (or mortice in UK) is the square hole that the tenon fits into. Mortise and tenon joints are extremely strong and the technique can be scaled up or down in size with great success. It is used extensively in cabinetmaking for joining rails to legs or stiles, and in many other constructions well. When properly designed, proportioned, and well made, mortise and tenon joints are strong and neat in appearance and they’re much stronger than other types of joints and you don’t need to fix the gaps in the joints. The joint has two basic components: a mortise which is essentially a hole cut into one board, and a tenon which is a tongue that is shaped onto the end of another board which will fit into the mortise. The cheeks are the sides of the tongue or mortise, and the shoulder is the portion of the tongue-board that rests against the mouth of the mortise board. The length of the tenon is the distance from the end grain to the shoulder. The width of the tenon is the distance from tenon edge to tenon edge. The thickness of the tenon is the distance from tenon face to tenon face. The mortise depth is the distance from the mouth of the mortise to the bottom of the mortise. The width of the mortise is sized to receive the tenon’s thickness. The mortise length is sized to accommodate the tenon’s width.

Types of mortise and tenon joints

Mortise and tenon joints come in several types like stopped/blind, through, angled, wedged, and many more, but they all consist of the same basic parts: a mortise and a tenon.

Through mortise and tenon joint

Through mortise and tenon joint is an extremely common joint that is formed by cutting the mortise completely through the stile and sizing the tenon to match. The end of the exposed tenon can be further secured by adding a very narrow slot, either diagonal or straight across the width of the tenon, then inserting a solid wedge into the slot once the joint has been assembled. This can greatly strengthen the joint’s holding power, but care should be taken to not split the joint apart by using an overly thick wedge.

Blind mortise and tenon joint

Blind mortise and tenon joint gives the outward appearance of a butt joint, however has all the strength and advantages of a mortise and tenon joint. The mortise does not extend completely through the stile, and therefore the tenon is not visible once the joint has been assembled.

Wedged mortise and tenon joint

Wedged mortise and tenon joint is a mortise and tenon joint that is  strengthened by the addition of a wedge. A thin kerf slot is cut into the end of the tenon, then after the tenon is inserted into the mortise, a wedge is inserted into the slot to secure the joint. Wedged joints such as these may not even require any glue, especially if the mortise is tapered to be wider at the wedge end, so that the joint can not be pulled apart by brute force.

Haunch mortise and tenon joint

Haunch mortise and tenon joint consist of a haunch which is basically a short tongue that protrudes from the rail’s shoulder, between the rail’s edge and the tongue’s edge. When a mortise and tenon joint is constructed with a stile that has a groove through which a tenon is cut, such as in frame and panel construction, the normal technique for forming a mortise and tenon would leave a void at the end of the slot, and this void would be visible on such assemblies as panel doors. In order to compensate for the slot, a haunched tenon is constructed so the haunch fills the groove at the tenon’s edge. Depending on the final use, the rail can have a haunch on only one side, or both sides, as required.

Loose mortise and tenon joint

Loose mortise and tenon joint is constructed by mortising both the side of the stile and the end of the rail, and then inserting an appropriately sized tenon during glue up. Even though the tenon is not integral to either piece, it still creates plenty of long grain to long grain glue surface to create a very strong joint.

Double mortise and tenon joint

Double mortise and tenon joint is used for rails that are more than ten times their thickness. This means that a standard 3/4-inch thick board move than 7 1/2 inches thick should be treated this way. The proportion between the tenon and the spaces between is the key, and not the actual number of tenons. It is recommended that the space be divided into thirds, two-thirds being tenon and one-third being space, equally distrubuted along the end of the rail. If the rail is of a material that is prone to cupping or warping, you can leave a short haunch between the tenons and notch the mortise to match.

Step-by-step guide to creating a mortise and tenon joint

Crafting a mortise and tenon joint requires a methodical approach and attention to detail. Here is a step-by-step guide to help you create a sturdy and visually appealing joint:

1. Measure and mark the mortise and tenon locations: Begin by carefully measuring and marking the positions of the mortise and tenon on your workpieces. Ensure that the measurements are accurate and consistent to achieve a proper fit.

2. Create the mortise: Using a mortising machine or a chisel and mallet, carefully cut the mortise into the workpiece. Start with shallow cuts and gradually deepen the mortise, ensuring that the sides are straight and the bottom is flat.

3. Cut the tenon: With a saw, such as a tenon saw or a bandsaw, cut the tenon to the appropriate size and shape. The tenon should be slightly smaller than the mortise to allow for a snug fit. Ensure that the tenon is square and the shoulders are clean and even.

4. Test the fit: Carefully insert the tenon into the mortise and check the fit. The joint should slide together smoothly without any excessive gaps or binding. If necessary, make minor adjustments to the tenon or the mortise to achieve the desired fit.

5. Secure the joint: Once you are satisfied with the fit, secure the joint using clamps or other fasteners. If desired, you can also incorporate additional features, such as wedges or pegs, to further strengthen the connection.

6. Refine and finish: Sand the joint to ensure a smooth, seamless appearance, and apply any desired finishes, such as stains or sealants, to protect the wood and enhance the overall aesthetic of the project.

Remember, practice and attention to detail are key to mastering the art of creating mortise and tenon joints. Experiment with different techniques and materials to find the approach that works best for your specific woodworking projects.

Conclusion

In the realm of woodworking, the mortise and tenon joint stands as a testament to the enduring ingenuity and craftsmanship of skilled artisans. This time-honored joinery technique, with its roots tracing back centuries, continues to captivate and inspire woodworkers of all skill levels, from seasoned professionals to passionate hobbyists. The beauty of the mortise and tenon joint lies not only in its exceptional strength and durability but also in its timeless aesthetic appeal. The clean, seamless connection created by this joint adds an elegant touch to any woodworking project, whether it be a sturdy piece of furniture, a striking architectural feature, or a delicate work of fine craftsmanship. The versatility of the mortise and tenon joint allows woodworkers to incorporate it into a wide range of designs, from the classic to the contemporary, ensuring that its appeal remains evergreen. As we have explored in this comprehensive guide, mastering the art of creating mortise and tenon joints requires a deep understanding of the techniques, tools, and materials involved. Yet, the rewards of this pursuit are immeasurable, as woodworkers unlock the secrets to crafting long-lasting, visually stunning pieces that stand the test of time. Whether you are a seasoned professional or a passionate beginner, the journey of discovering and perfecting the mortise and tenon joint is one that promises to enrich your woodworking journey and elevate your craftsmanship to new heights.