fingerjoints

Finger joints, also called box joints, are a woodworking joinery method where two pieces of wood are cut with interlocking rectangular fingers. The fingers mesh when joined and glued, producing a strong corner with a large glue surface. They are commonly used to form the corners of boxes, drawers, and other box-like structures, as well as for extending boards end to end.

Finger joints have roots in early wooden boxes and crates, but gained widespread use with advances in machine tools and plywood. Modern joints are prized for simplicity, repeatability, and the clean appearance of the corner, providing strong, durable furniture and cabinetry.

Fingers are produced by a table saw, router, or milling machine, often with a jig or CNC router. Finger width commonly ranges from 6 to 12 mm (1/4 to 1/2 inch), and the number of fingers depends on stock thickness. Joints can be through or end-to-end. Accurate cutting, even glue application, and clamping are essential.

Performance and limitations: The joint provides significant shear and tensile strength due to the large gluing area and interlock, making it strong for box and cabinet work. However, finger joints are visible and not ideal for concealed joints. They are sensitive to wood movement with moisture changes, and end-grain gluing can be weaker if not prepared.

Variants and applications: Box joints and through-box joints are common, with variants producing longer joints along the length of boards. They are widely used in cabinetry, drawers, crates, and instrument cases, and work with solid wood and plywood. They can be cut by hand or with power tools and CNC equipment.