The Essential Timber-Frame Joint
Learn from a veteran framer's technique for making large pegged mortises and tenons.
Synopsis: For this edition of “Master Carpenter,” builder and educator Will Beemer shows how to create a classic timber-frame joint, a large pegged mortise and tenon. Beemer begins the process by establishing a level work surface. Because timbers can be so large, it might be necessary to work on sawhorses with shorter legs. It’s also important to find the arris, or the intersection of the two sides of the timber that are square to each other. This becomes a key reference point. Cutting a tenon always begins with the shoulder and should be cut carefully. Next, cut the housing and the mortise. To finish, draw the joint tight with an offset peg. This article includes a number of sidebars, including one about a special tool of the trade that helps timber-framers to cut plumb holes using a mirror; a trick of the trade describing a process known as the French snap; and a brief guide about how to deal with timbers that are not perfectly milled and uniform.
At first glance, a timber frame is all about the exposed wood and the strength implied by its large scale. Look a little closer, and you’ll see that the real magic lies in the joinery that unifies the wood into a structure. The joint I’ll concentrate on here is the mortise and tenon, which is ubiquitous throughout furniture-making and cabinet making and is used to join one piece coming in at an angle (often 90°) to another piece. As an extension of the long grain, a tenon inserted into a mortise increases the captured surface area within a joint. In a timber frame, pegs (also known as trunnels or tree nails) secure the joint and prevent rotation and withdrawal. Modern mechanical fasteners can be used instead of pegs, but in centuries…