Hand-Cut Lapped Dovetails
In a time where automation has taken over, it is satisfying to know that there are still some things better made by hand. Of course there are those that will argue the merits of router made dovetails with the use of jigs – but they too have their limitations. When we consider complex joints such as long and short lapped dovetails cut into brittle exotic woods such as cocobolo or bubinga, hand-cut joinery is the way to go. The resulting joint is both very strong and visually interesting.
Let’s consider making a drawer with long and short lapped dovetails in the front corner joints. This is one case where cutting the tails first is preferable, since it makes it easier to transfer the pattern this way. If you cut pins first on lapped dovetails, it is quite difficult get your pencil into the enclosed area under the pins to transfer the pattern onto the tails board. Ensure that your stock is milled flat and square – this will affect the quality of your layout and the joint. For clarity: the pins are the pattern on the drawer front, the tails are the pattern on the drawer sides.
Establish a scribe line on the drawer side using a marking gauge. Set the gauge to the length of the longest tails. The drawer front is purposely left thicker than the sides, so that there is enough wood beyond the tail ends to maintain strength in the drawer front. Typically you would leave at least 1/8th inch or more of wood between the end of the tail, and the front of the drawer.
Scribe both sides of the board, and both edges. Darken the scribe lines using a 0.5mm mechanical pencil with HB lead. Next layout the tails using a T-bevel. The absolute angle is not important – but ensure you do not have excessive tail angles leaving them fragile, or not enough angle leaving them looking like box joints. Somewhere around 11 degrees is good, or a ratio of approximately 1:6. Extend the layout lines across the end of the side boards using a small square. Layout a second scribe line indicating the ends of the two shorter dovetails across the tops of the two tails in the middle of the pattern.
Mark the waste wood with and “x” to remind yourself to saw on the waste side of the line. Place the side board between a couple of backup boards in the vise to reduce vibration during sawing. Add an F-clamp to further reduce vibration and improve your cut quality. Tilt the wood in the vise so that you are sawing vertically. Use a fine tooth saw with 32 teeth per inch to saw your tails.
Chopping the tails starts with making a relief cut just on the waste side of the scribe line.Since the chisel is beveled on one side, it tends to move across the scribe line during chopping if you don’t use a relief cut. Chop into the waste about 1/32 inch on the waste side of the scribe line to make the relief cut. Now place your chisel into the indent of the scribe line and chop down.
Your next step is to remove the waste from between the tails by tapping the chisel horizontally into the waste, removing triangular pieces about 1/16th inch thick. Chop down in successive cuts until you are ½ way through the board, then flip the board and complete the chopping from the other side. Don’t chop the waste on the outside of the upper and lower tails. Remove this waste at the edges of the side board by placing the board on its edge, and sawing off the waste along the scribe line between the edge of the board, and the bottom of the first tail. Use a 1” chisel to pare the sawn shoulder down to your scribe line. Using a small chisel, clean up any tear out between the tails.
Now you may chop off the ends of the two short dovetails by chopping half way down from the first side, then flipping the board and chopping the rest of the way.
Pare the tops of the short tails flat with a paring chisel.
To transfer the tail pattern to the drawer front for cutting the pins, place the drawer front vertically in your tail vise. Place the tails pattern over the end of the front board and transfer the tails pattern to the end of the drawer front board with a 0.5mm mechanical pencil. Mark the waste area between the pins with an “x”, then saw out the pins pattern, staying on the waste side of the line.
You cannot saw through the board on lapped dovetails, so you have to tilt your saw handle down 45 degrees and saw until the blade touches the scribe line at the bottom, and the end of the tail pattern at the top. Chop the pins from one side only. More paring is required since you will be chopping and removing waste without the benefit of sawn edges on the pins as you get deeper in the “tail pockets” or into the waste area between the pins. It is very important that you add support blocks on either side of your stock while chopping. These blocks prevent the outside pin from splitting and breaking off. Clamp the support blocks tight to either side with an F-clamp.
It is advisable to use a shim when doing the final chopping of the “tail pockets” to guide the chisel. This will keep the chisel from creeping across the scribe line and will ensure that the depth of each tail pocket is equal. The “tail pocket” is the waste area removed when we are chopping the pins.
Dry fit the dovetails by placing a block over the tails, and gently tapping the tails into the pins of the drawer front. If the joint binds, pare the pins until it fits. Ensure that the fit on the outer pin is not excessively tight or it will fracture, as the outer pin is not supported.
The finished joint will be glued and hand planed flush. Congratulations, you have just made a very strong and decorative joint.