boxjoint

Box joint, also known as finger joint, is a woodworking joinery method used to form a strong corner between two pieces, most commonly to assemble the sides of a box, case, or drawer. It consists of a series of square or rectangular teeth cut into the ends of the pieces that interlock with corresponding slots on the mating piece. When glued and clamped, the joint provides a large continuous glue surface and helps with alignment.

Anatomy and geometry: The teeth are typically square to maximize contact and are sized according to the material thickness. Common tooth widths range from about 1/4 inch to 3/8 inch, with the number of teeth adjusted to balance strength and fitting ease. The joint relies on matching projections (fingers) and recesses (slots) to create a tight interlock across the joint line.

Construction methods: Box joints are usually cut with a table saw or a router, guided by a jig that ensures precise tooth width, spacing, and alignment. The joints are often cut on the ends of the boards that form the sides of the box, then dry-fitted, glued, and clamped until the adhesive sets. Accurate cutting and consistent glue-up are essential for a clean, square result.

Applications and advantages: Box joints provide strong, evenly loaded corners with good resistance to pulling apart and twisting. They are widely used for boxes, chests, drawers, and other box-like assemblies. The joint is relatively forgiving to small misalignments and can be efficiently milled with modern jigs and power tools.

Limitations: Requires precise cuts and careful clamping; delicate workpieces may be damaged by tear-out or misalignment. Finishing can be more involved than simpler joints due to the many contact surfaces.

See also: finger joint, dovetail.