through dovetail tenon joint

The through dovetail tenon joint is an L-joint where a dovetail-shaped tenon is inserted through a corresponding mortise in the second member. The connection combines the form of the dovetail with the through-tenon principle, creating a tension-resistant corner joint without additional wooden fasteners. The trapezoidal widening of the tenon prevents withdrawal in one direction, while the through-insertion enables a visible and verifiable connection.
This joint belongs to the tenon joint family and unites principles of the dovetail joint with those of the through-tenon. It shows kinship with the Japanese ari-gata-sammai-hozo and the half dovetail. Unlike the blind tenon, the through dovetail tenon visibly emerges on the opposite side, enabling aesthetic design while simultaneously facilitating assembly and quality control.
The geometry consists of a trapezoidally widened tenon whose cheeks run at a characteristic angle of approximately 1:6 to 1:8 to the tenon axis. The corresponding mortise is chiseled conically into the receiving member. The tenon penetrates the member completely and protrudes on the opposite side. The shoulders of the tenon rest against the face of the receiving member and transmit compressive forces. The dovetail-shaped widening prevents withdrawal of the tenon under tension, while the lateral cheeks absorb transverse forces.
The through dovetail tenon joint offers very high tensile strength through the dovetail undercut. The connection is self-locking and requires no additional fasteners such as wedges or pegs. The through-tenon enables visual quality control and can be sawed flush or left protruding as a design element. The connection is reversibly assembled if not glued. However, fabrication is labor-intensive and requires very precise fitting accuracy. The dovetail notching significantly weakens both members. With too shallow a dovetail angle there is risk of withdrawal, while with too steep an angle shear forces can cause the cheeks to break out.
Traditionally, the through dovetail tenon joint is used in sill constructions in timber building where high tensile forces occur. In furniture making it is used for high-quality frame constructions in tables, chairs, and cabinets. In door and window frames in interior construction it is employed when a durable and tension-resistant corner joint is required. In traditional timber-frame construction it is used for plates and sill connections. The joint is particularly suitable for visible applications where craftsmanship quality should be demonstrated.
Fabrication is carried out by precisely marking the dovetail tenon with its angled cheeks, accurately sawing the tenon contour, and cleanly finishing the bevels. The mortise is marked, pre-cut with a saw, and conically chiseled out with mortise chisels. The dovetail angle must match exactly on both members. Fitting accuracy is crucial for the strength and durability of the connection. For visible applications, careful surface finishing of the protruding tenon end is required.