Dovetail joint

Laying Out the Joint

 * Prepare two piece of wood about 12 inches long, 3 inches wide and ½ inch thick. Your actual dimensions will depend upon the piece you're building, but practice on                these boards. Mark the two boards with “front,” “back,” “left,” “right,” “top” and “bottom.”


 * Set a Marking Gauge to about 1/64th of an inch less than the thickness of your boards. Scribe both of the boards on one end, making sure to scribe both the front and back faces. You should have a total of four scribe lines.


 * Clamp one of the boards, scribed end up, in a bench vise. Measure over 1/8 inch from the left side of the board, and mark this with a thin pencil line. Then measure over 1/4 inch from the same end and mark this with your pencil. Lastly, mark both these measurements on the right side of the board.


 * Use a pair of dividers to divide out the distance between the 1/8 inch marks on the clamped board. Aim for four divisions, which will give you three dovetails. Put a pencil mark at each division.


 * Measure 1/8 inch over from each side of the two middle division marks, creating two 1/4 inch areas with the division mark at the center. These, together with the 1/4 inch areas on either side of the board, will become the pins of the dovetail joint.


 * Set a dovetail marker at the first 1/4 inch mark on either side of the board, and use it to scribe an upward-sloping line along the thickness of the board. Scribe the line first with a sharp blade, then darken with a pencil if desired. Move the marker to the next line, but this time the angle of the line should be directed towards the first line. Continue on to the next line; this one will be in the same direction as the first. Continue the process until you reach the other side of the board, alternating the angle of the line each time. It should look like this when you're done: / \ / \ / \.


 * Use a carpenter's square to extend the scribe lines down one face of the board. You may scribe on either face of the board. Make the extended lines with a sharp blade, darkening with a pencil if desired. The lines only need to go down to the scribe line you made in Step 1.

Cutting the Pins

 * Adjust the board in the vise so that the horizontal scribe line is about 1 inch from the vise. Grasp a dovetail saw in your hand and rest the blade lightly in the first angled scribe mark on the end of the board.


 * Cut through the line, making sure to keep the saw aligned 90 degrees to the sides of the board. Keep an eye on the straight line on the face of the board—you should be sawing right through this line. Go down only as far as the horizontal scribe line. Repeat this step for each of the angled lines on the end of the board.


 * Clean out the waste between the pins. Saw a relief kerf in the center of the waste pieces while the board is still in the vise, then clamp the board to a bench and chisel away the remaining waste. Chisel only as far down as the horizontal scribe line, then use a square and a chisel to square up the sides of the pins.

Scribing and Cutting the Tails, and Assembling the Joint

 * Place the second, uncut board on a work bench, scribed end toward you. Position the board with the cut pins over the uncut board with the little ends of the pins facing toward you. Line up the face of the cut board with the horizontal scribe line on the uncut board. Make sure the sides of the boards are flush, then carefully clamp them to the bench in this “L” position with a long bar clamp. Note which sides and faces you are lining up; it helps to place matching numbers or letters on the boards so you can reassemble the joint later exactly the way you have it now.


 * Use a sharp blade to scribe the tails from the pins. Scribe both sides of each pin, except for the two outside half-pins, which will only have one side to scribe. Unclamp the board with the pins and place the now-scribed board in the vise.


 * Use a sharp blade and a carpenter's square to extend the scribed lines on the end of the board. Rest the tip of the blade on the end of the first line, then move a square to the end of the board so that it touches the blade at 90 degrees to the face of the board. Extend all the scribed lines, and darken with a pencil if desired.


 * Adjust the board in the vise to a comfortable cutting height, then cut away the pins on this board. Be sure to follow the angle of the lines on the face of the board. Saw only as far down as the horizontal scribe line.


 * Clean out the waste between the tails. Use the dovetail saw to slice away the mating pieces of the two outer pins while the board is still in the vise, taking care to follow the horizontal scribe line as a guide. Use a chisel to clean out the rest of the waste, being especially careful at the horizontal scribe line. If you go past this line when you're chiseling, you'll leave a gap in your finished dovetail joint.


 * Clamp the board with the pins into the vise. Position the board with the tails over the clamped board, matching up the pins and tails. Try to assemble the joint with no hammering, but you can use a mallet or dead-blow hammer lightly if you need to. If everything has gone smoothly, you should have a perfect fit with no gaps or tight spots. Glue the joint together and Hand Plane the surfaces once the glue has dried.