dado

A dado is a rectangular groove or channel cut across the grain of a board, typically running from one edge partway or fully across the width. It sits perpendicular to the wood fibers, which distinguishes it from a groove that runs with the grain. The cut is usually made with a dado blade or stack of saw blades on a table saw, and it accepts the edge or tongue of another board, creating a strong, flush joint that resists racking.

In frame-and-panel construction, dadoes hold the edges of panels or shelves in place without requiring fasteners along the joint line. A shelf sliding into a dado along the inside face of a cabinet side will sit flush and square if the cut is precise. The width of the dado must match the thickness of the incoming board closely, typically within 1/32 inch, or the fit will be sloppy or the board will jam.

Variants and adjacent cuts

A stopped or blind dado does not run the full width of the board; it ends short at one edge, leaving solid wood that remains visible on the face. This is common on the front of a cabinet where a full dado would be seen. A through dado runs completely across and shows on both sides. A rabbet is similar but runs along an edge; a groove runs with the grain rather than across it. These terms are sometimes used loosely, but the distinction matters for both strength and appearance.

The dado blade itself is a set of thin carbide-tipped saw blades and chippers stacked together on the arbor to cut a wide channel in one pass. Blade widths range from 1/8 inch to over 1 inch. Feed speed must be controlled to avoid burning the walls of the cut, particularly on hardwoods. The depth of the dado, typically one-third to one-half the board thickness, affects how much load the joint can carry before the shelf or panel deflects.

Accuracy in dado layout and cutting is critical. A dado cut too shallow leaves gaps; cut too deep and the incoming board bottoms out before seating fully, throwing off cabinet dimensions and assembly. Many furniture makers use a backer board behind the work to reduce tearout on the exit side, especially on figured or cross-grained stock. The term itself comes from the Italian dado, originally meaning the lower wall section in Renaissance interior design, which was paneled and divided by vertical elements.