Wood assembly, dovetail joint
Wood assembly, dovetail joint
-
Difficulty:
Close DifficultyBeginner Do-It-Yourselfer - EasyIntermediate Do-It-Yourselfer - ModerateExperienced Do-It-Yourselfer - DifficultProfessional - Expert
In woodworking, wood assembly by traditional means without nails or screws yields a more natural, attractive and professional finish. The joining method is chosen according to one’s tools, knowledge, and habits as well as according to the project at hand.
The dovetail joint is achieved by making, on a wood board, trapezoid tenons to be inserted in grooves of the same shape carved out of another board. The shape produced by this pattern is reminiscent of a dove tail, hence the name. This type of joint provides boards with added strength to resist traction.
Print
Tools and materials required
- TOOLS
- Dovetail saw (back saw)
- Wood chisel
- Vice
- Square
- Pencil
Optional:
- Router with appropriate bit
- Dovetail guide
Before Assembly
A dovetail joint requires time and patience. Indeed, in order for the two boards to fit perfectly, both steps, drawing and cutting, have to be extremely precise.
This work is made easier thanks to commercial comb-shaped templates. When used with a router and appropriate bits, they produce shapes quickly and precisely.
The present guide however describes how to make dovetails manually.
Note:
This traditional technique is particularly interesting when boards of different colours are used thus highlighting the dovetail pattern.
Steps
1.1 Trace a line, determining the thickness of A on the adjacent side, at the tip of B. This line will indicate the length needed for the tails.
2.1 The width and the space between each tail is up to the carpenter: the tenon and tail can be exactly the same size, but the tenon can also be smaller, which is more common.
2.2 A rule often followed consists in dividing the width of the board to have the tails by the thickness of the board with the tenons, then rounding to the highest even number, and finally dividing by two.
2.3 For example, if B is 3 ½" wide and A is ¾" thick, the following calculation is made: 3.5 ÷ 0.75 = 4.68. The result is rounded to the highest even number = 6, then divided by 2 = 3 dovetails. This rule is not absolute, and one can plan an extra tail or remove one.
2.4 In the example shown here, the plan calls for three tails, one of which consists of two half-tails.
3.1 In the space between the tip of B and the line previously traced (determining the thickness of A), divide the area in a number of rectangles that is equivalent to the even number obtained previously (here: 6).
3.2 Since each rectangle must be of the same size, divide the width of B by 6 (here: 0.58 in. or 9/16"), which gives the width of the rectangles.
3.3 Make a mark on the edge of B, at the centre of the leftmost rectangle.
3.4 From that mark measure 1/8" to the right and mark.
3.5 Again from the first mark, measure 6/8" (or 3/4"), at a 900 angle, and mark.
3.6 Trace a line between the last two marks; it will have a slope of 1:6.
3.7 Extend that line to the line representing the thickness of A. The first half-tail is now traced. You can make a cardboard template to reproduce the same slope without having to measure each time.
4.1 Repeat (but in reverse) in the rightmost rectangle; you will then have two half-tails and an empty space between them.
4.2 Now draw the complete dovetails between the two half-tails; at this moment you can decide on the width of the tails and on the space between them (which will affect the size of the tenons).
4.3 Once the tails are drawn, hatch the parts between them to avoid mistakes.
5.1 On the tip of B, extend the lines representing the tails’ sides, which will form the tails’ heads. Hatch again the portions to be removed.
5.2 Secure B in a vice, tip facing upward.
5.3 Juxtapose the edge of the saw’s teeth on a line at the tip of the board. The teeth themselves must bite into the hatched area, and not in the line (if you centre the saw on the line, you will remove too much material, and the two parts will not match).
5.4 Saw along the corresponding profile line, up to the line representing the thickness of A.
6.1 When all the saw kerfs (saw-cuts) have been made, gently remove the hatched parts with a wood chisel of appropriate size.
6.2 To do so, put the board down on its flat side, and remove a first half of the thickness.
6.3 Turn the board over and remove the other half. Sand if necessary to smooth the surface.
7.1 Lean the tails of B on the tip of A, where they will be inserted between the tenons.
7.2 Follow the contours of B’s tails to trace the contours of the tenons on A.
7.3 Hatch the parts to be removed.
8.1 Carry over the exact thickness of B on all the sides of A, to know where to stop sawing.
8.2 Then extend, on each side of A, the lines representing the tenons’ profiles.
8.3 Hatch again the parts to be removed.
8.4 Immobilize A in a vice, then saw along the lines until you reach the line representing the thickness of B.
8.5 When all the saw kerfs have been made, gently remove the hatched parts with a wood chisel of appropriate size.
8.6 Sand as necessary to smooth the surface.
9.1 Assemble the parts dry, readjust as necessary.
9.2 Apply glue and proceed to the final assembly.
Variation:
To hide the tails’ heads on a given surface, (e.g.: the front part of a drawer), a concealed dovetail (also called “lapped” or “half-blind”) can be made. Rather than crossing the board through and through, the tails only cross half-way and are therefore half as long.
If the tails are cut at a right angle, rather than giving them a trapezoid shape, we obtain a “straight tail joint”, also called a “finger joint”, which is simpler to make, but in which the tails do not act as a “lock”, since they have no “head”.
Helpful Links
Customer Services
About RONA
