The dado is a useful joint for door and window frames, shelving and furniture. After the boards are planed to dimensions, square a knife line across one of them at a distance from the end equal to the thickness of the stock plus the desired extension as shown in Fig. 30 at A. This line marks the inner cut for the dado.

Place the second board on the first one, mark the width of the stock and square a second line across as at B. Then carefully mark the depth of the dado with a gage.

Unless you are an expert with the saw, it is advisable first to make a V-groove for starting the saw as at C. This insures a clean and very accurate cut. Use a backsaw or any fine handsaw. Start the cut on the farther side and gradually lower the saw to a horizontal position as at D. Cut exactly to the depth of the gage lines on both edges.

Remove the waste wood with as wide a chisel as possible, working first with the bevel down and then with the bevel up as at E. Test the bottom of the dado with a square.

If the dado is made accurately, the parts Should fit without play when pressed firmly together as at F. The joint may be fastened with glue or nails, or both. It must be very accurately fitted if glue alone is to be used.

Fig. 30. - Steps in making a dado joint. Marking the inner cut for the dado and the width of the stock; making a V-groove for starting the saw ; Sawing to the gage lines, removing the waste wood with a chisel, and testing the joint.