Tails, pins and the baseline
The parts, as Veritas names them
- Tail
- The flared part that looks like a dove's tail; the board that carries them is the tail board.
- Pin
- The part that fits between the tails; the board that carries them is the pin board.
- Half-pin
- A pin at the edge of the board, cut on one side only. Veritas says to leave at least 1/4 in for each so the boards do not split as they are knocked together.
- Baseline
- The line, set with a marking gauge to the mating board's thickness, where the tails and pins start.
- Waste
- Everything sawn or chopped away between the parts — marked with an X so the saw stays on the right side of the line.
The tails widen toward the end of the tail board, so once the pins are in place the tail board cannot be pulled away along its length; it can only come apart the way it went together. That is why a drawer's tails are cut on its sides: the pull on the front runs along the sides' length, the one direction the tails lock. The Wood Handbook lists the dovetail among the joints that interlock so that edge grain inside the joint bonds to edge grain, which is what makes a glued corner joint strong.
Three common dovetails
| Type | Shows on | Resists | Typical use |
|---|---|---|---|
| Through | Both faces of the corner | Pull along the tail board | Boxes, chests, carcases |
| Half-blind | The side only; a lap on the pin board hides it from the front | Pull along the tail board | Drawer fronts |
| Sliding | The edges only, where the housing runs out | Pull across the housing | Shelves into sides, legs into tops |
The through dovetail is the one cut first by most learners; the method is in cutting dovetails by hand.
- Through dovetails show end grain on both boards. They are the simplest to lay out and fit, and the one to start with.
- Half-blind dovetails stop short of the pin board's face, leaving a lap that hides the joint from the front. The tails are shorter than the pin board is thick, so its sockets cannot be sawn straight through and are finished with a chisel.
- Sliding dovetails are a flared tongue along the end or edge of one part sliding into a matching housing in another. They are assembled by sliding, not by tapping together, so the fit along the whole length matters.
- In Japanese carpentry a dovetail-shaped part is called ari, and JAANUS describes it in splices that lengthen timbers as well as in corner joints — see Japanese joinery.
- Other corner joints: the square-fingered box joint and the rest are compared in choosing a wood joint.
Slope, size and spacing
The slope of a tail is given as a ratio: 1:6 means the edge moves across by one unit for every six along. Veritas makes its saw guides at 1:6 for softwood and 1:8 for hardwood, the traditional ratios, and at 14° for matching antique dovetails and those cut with a router — a reason to take any one figure as a convention rather than a law. The guides take boards from 1/4 to 1 in thick, and Veritas suggests keeping the number of tails small at first, since every extra tail is another chance for one to be off, and sizing tails and spaces to your chisel so the waste is easy to clear.
- Saws: a fine-toothed saw that tracks straight — see backsaws and Japanese saws. Veritas's guides need a backless saw, because a back would ride on the guide.
- Layout: a marking gauge for the baseline, a sliding bevel or a marker for the slope, a knife for transferring tails to pins — see measuring and marking.
- Waste: sharp bevel-edge chisels and a mallet — see chisels.
- A marker of your own: the dovetail projects page builds a 1:6 and 1:8 marker, and a box to use it on.
Choosing a dovetail
- Which way the pull runs: along the tail board's length
- Whether the joint may show on the front: through or half-blind
- A shelf or a corner: sliding or through
- A slope for the wood: Veritas gives 1:6 for softwood, 1:8 for hardwood
- Half-pins of at least 1/4 in at the edges
- Tails and spaces sized to a chisel you own
Sources
Slope ratios are the ones Veritas names for its guides; they are conventions, and other makers' guides and jigs use other figures. No universal dovetail angle is given because no source reviewed sets one.
- 1.
Dovetail Saw Guides — instructions (INS-622_B). Veritas Tools Inc. (Lee Valley), 2018.
Used for: The joint's terminology — tail, tail board, pin, pin board, half-pin, waste; guides made in the traditional ratios of 1:6 for softwood and 1:8 for hardwood and at 14° for matching antique and router-cut dovetails; boards from 1/4 to 1 in thick; half-pins at least 1/4 in at each edge so the boards do not split in assembly; Veritas's view that modern glues and joinery can equal or beat the dovetail's strength, the joint being kept for its looks.
- 2.
Chapter 10: Wood Adhesives: Bond Formation and Performance. USDA Forest Service, Forest Products Laboratory — Wood Handbook, FPL-GTR-282, 2021.
Used for: The dovetail among the end-to-edge joints that interlock so edge grain bonds to edge grain.
- 3.
ari 蟻 (glossary entry). Japanese Architecture and Art Net Users System (JAANUS).
Used for: Ari as the Japanese term for any dovetail-shaped part of a joint, with dovetails used in splices and right-angled joints, including half, lapped and blind forms.
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