Tips for Making Rabbet and Dado Joints

Rabbets are made along a board’s end or edge, while dadoes are cross-grain grooves across a piece’s face. Widely used to join horizontal shelves to uprights, dadoes are strong – the dado’s lip bears the shelf weight.

Rabbets are cut along board edges and the mating piece rests within the rabbet. Used at corners or for recessing back pieces, rabbets help cut down visible end and edge grain. And because of the extra surface area they offer for gluing, they’re very strong.

Cutting a rabbet with hand tools is a bit tricky – the goal is to make cuts as perpendicular to the board surfaces as possible. A backsaw or dovetail saw, a scrap of wood as a guide, and some type of vise or clamp will help you do the job.

First, use a combination square to mark out lines on the end, face, and two edges. Clamp on a wood-scrap guide, lining it up with the face line, and cut to the point where the end cut will intersect the face cut. The end cut is the tricky one: there’s no good way to clamp on a guide. Cut down carefully to meet the face cut. Clean and shape the rabbet with chisel and file.

Portable power tools make rabbets easier. An electric router equipped with a self-guiding rabbet bit will make the groove in one pass. If you have a portable circular saw, set it to the desired depth and cut along the face line first. Then make repeated passes through the waste wood. If enough cuts are made, the saw will clean out the waste or you can remove it with chisel and file.

Dadoes are the most difficult of common joints to make with hand tools. The hard thing is to get a groove with a smooth, even bottom. To make a dado, first draw the border lines across the face. Use the edge of the shelving material as a guide if you are making dadoes in uprights. Then, extend the lines around the edges using a combination square and connect the two edge lines at the proper depth. Now, the dado is mapped out.

Clamp on a straight piece of scrap along one face line, and cut to the right depth. Move the scrap to the other face line and repeat. If you make extra saw cuts through the waste area, chiseling will be easier and the bottom of the dado will be more uniform.

To remove any remaining wood, use a chisel with the beveled side down, first tapping lightly with a hammer and then smoothing out the groove with several hand-held strokes.

Power tools are best for dadoes. The router, equipped with a dado bit, smoothens the cut as it goes. Clamp a guide onto the work for the router base to follow. There are dado blades for stationary machines and for portable power saws.

To cut dadoes with a standard power saw blade, set the blade at the right depth, cut the borders using a guide, and make repeated passes through the waste wood until it virtually falls out. Dress each groove with light chisel strokes.