Rabbet cuts are made in the edge of a board to fit into a dado. Rabbet and dado construction is used when making bed frames and shelving. This provides more support than a simple butt joint. Rabbet and dado construction is not as effective for items that will be moved frequently while filled or while supporting a full load. Use mortise and tenon or dovetail joints instead. Floating shelves made with rabbet and dado joints permit easy movement.
Making a Rabbet
Choose a piece of wood at least 3/4-inch thick. Wood for rabbet joints must be at least twice as thick as the cut to prevent splitting or breaking off the remaining wood.
Set the depth of your desired cut according to manufacturer's directions if using a table saw, router or jointer.
Look at your board and decide whether the top or bottom surface is the best-looking. Use the best surface for the visible side of any furniture or shelf you intend to make. Mark the depth of the rabbet cut along the "worse" side of your board. See photo 1 at the Woodworker's Journal, in the article "Skill Builder: Cutting Rabbets, Dadoes and Grooves." The depth of the vertical part of that rabbet joint is half the thickness of the board from the "bottom." The depth from the horizontal part equals the full thickness of the second board.
Make the cut across the grain, not along the grain. Because you are removing material, the board will not be as strong at the rabbet cut as it is everywhere else, even if the joint will be fully supported by a dado. Cutting along the grain will eventually result in a break along the grain line.
Apply carpenter's glue to the entire surface of the rabbet cut and allow to dry until tacky. Insert the rabbet into its matching dado. Make a permanent joint using wood screws or paneling nails.