Single Dovetail, Through Dovetail and Lapped Dovetail Joints
The single dovetail is a mechanically strong joint for rails which have to take weight.
To make one, mark out and cut the pin on the rail with a. Make the slope of the pin 1 in 6 for , and 1 in 8 for . Mark the shape of the pin all round the rail end and cut accurately to all lines.
Transfer the pin shape to the frame piece by marking with a pencil or knife.
Saw down the shoulders of the dovetail cut-out and make an extra cut in the centre of the waste to help chiselling out. Tap the joint together dry before, to check for fit.
The through-dovetail is the strongest and most decorative of the corner joints; it is used extensively for the backs of drawers.
Before you start, assemble all the pieces of wood to be joined and mark the mating pieces forming the corners, to avoid any mix-up later on. Then plane the ends of each piece on a shooting-board, allowing about 1-5 mm. G16 in.) for overall wastage.
Set the cutting gauge to the thickness of the wood plus 0.75 mm. (1/32- in.) — the allowance for waste on each corner. Mark gauge line (a) on all sides and edges.
The size and number of tails depends on the job. On a 100 mm. (4 in.) deep drawer, for instance, three 25 mm. (1 in.) tails will be ideal. On larger work, use coarser tails.
Use a dovetail template (angles 1:6 for; 1:8 for ) to mark the tails. Square the lines across the ends.
Cut down the tails with a dovetail saw , skimming the lines on the waste side. Remove most of the waste with a. Trim out with a narrow, bevel-edge chisel .
To mark out the pins, chalk the end grain and clamp the piece upright in the vice . Place the tails over the chalked end, using a support block at the other end of the tail member. Then mark off the tops of the pins with a fine scriber, a needle or the tip of the dovetail saw. The lines will show up in the chalk. Continue them in pencil, square down to the shoulder line (a).
Cut down the pins with the dovetail saw , saw out the bulk of the waste with a coping saw and trim to the shoulder lines with the largest possible chisel.
Save time when making several joints by cutting all the tails at once with the tail pieces clamped together in the vice.
Test the joints for fit , leaving them dry at this stage in case further trimming is needed. If all is well,and cramp the carcase together. Finally, clean up the joints with a plane.
Lapped dovetail and other variations
The lapped dovetail is used where the ends of the tails would spoil the appearance of the work, such as on drawer fronts, bookcases and better-quality framing.
The pins go on the lapping piece and the tails on the side piece.
Cut and plane the side to the exact length of the drawer, less the thickness of the lap-3 mm. (1 in.) on 19 mm. (¾ in.) wood, a proportion of 1: 6. Cut and plane the front to the size of the opening it has to fit.
Set the cutting gauge to the thickness of the front, less 3 mm. For the lap. Gauge line (a) on the end of the front and on the inside, and line (b) all round the end of the side with the cutting gauge at the same setting. Mark the tails as for the common dovetail and cut them in the same way.
Butt the tails against line (a) on the front and mark off the shape of the pins.
Now mark the depth of the pins on the inside of the front. Saw the pins at 45°, with the wood held upright in the vice. Chop out the waste, keeping the chisel short of line (a) until the bulk is removed.
The overhang of the pins prevents cutting straight into their corners. Ease out the waste at these points.
Trim the inner faces of the pins by paring with a bevel-edge chisel. Finally, run a groove for the drawer bottom through a tail so that it will be covered by the lap.
On bookcases or sideboard carcases, cut mitres between sides and the top and bottom on the corners that show.
Variations on the joint are the double lapped dovetail, which leaves only a small amount of end grain showing, and the secret, or mitre, dovetail which conceals its construction entirely.
In both the double lapped and the mitre dovetail joints cut the pins first.
Considerable experience is required to make these joints successfully.
For more woodworking hints and tips from Ted ‘Woody’ Mcgrath – Professional Woodworker, Educator, Member of AWI , Please Click Here!