dovetail tenon joint

The dovetail tenon joint is an I-connection that uses a conically widened tenon with a dovetail-shaped cross-section. The tenon engages into a correspondingly shaped mortise that widens inward. The characteristic wedge shape prevents withdrawal in the longitudinal direction and makes the connection tension-resistant.
This joint belongs to the group of dovetail and tenon joints and shows similarities with the Japanese Ari-otoshi and other conical tenon forms. Comparable principles can be found in wedge connections and other self-locking wood joints that act positively against tensile forces.
The tenon is manufactured with dovetail-expanding side surfaces, typically at an angle of 1:7 to 1:8. The corresponding mortise widens inward accordingly. The connection can only be made by laterally sliding the tenon in. The conical shape creates a self-locking effect under tension loading.
The dovetail tenon offers excellent resistance to tensile forces through the conical anchorage. The large contact area between tenon and mortise enables high load transmission. The connection is tension-stable and positively fitted without additional fasteners. However, it is more difficult to manufacture than a simple tenon and can lead to wood splitting with incorrect angles.
Traditionally, this joint is used in structural timber construction for highly loaded connections where tensile forces occur. Typical applications are ceiling joist systems, sill connections, rail connections, and purlin connections. In modern timber frame construction, it has gained new significance through CNC manufacturing. It is also used in high-quality furniture making for permanent frame connections.
Manufacturing requires precise machining of the dovetail-shaped geometry. Traditionally done through marking, sawing, and chiseling, today often by CNC pre-cutting machines. The dovetail angle must be maintained exactly to achieve optimal strength without splitting risk. The fit must be tight but not too firm.