A dovetail joint or simply dovetail is a joint technique most commonly used in woodworking joinery. Noted for its resistance to being pulled apart (tensile strength), the dovetail joint is commonly used to join for example the sides of a drawer to the front. A series of pins cut to extend from the end of one board interlock with a series of tails cut into the end of another board. The pins and tails have a trapezoidal shape. Once glued, a wooden dovetail joint requires no mechanical fasteners.
The dovetail joint probably pre-dates written history. Some of the earliest known examples of the dovetail joint are in furniture entombed with mummies dating from First Dynasty of ancient Egypt, as well the tombs of Chinese emperors. The dovetail design is an important method of distinguishing various periods of furniture.
Dovetails can be cut by hand or by machines, often with an electric router and using one of a range of commercially available jigs or templates. Although it is technically a straight forward process, hand-cutting dovetails requires a high degree of accuracy to ensure a snug fit and so can be difficult to master. The pins and tails must fit together with no gap between them so that the joint interlocks tightly with no movement. Thus the cutting of dovetails by hand is regarded as a mark of skill on the part of the craftsperson.
The angle of slope varies according to the wood used. Typically the slope is 1:6 for softwoods and a shallower 1:8 slope for hardwoods. Often a slope of 1:7 is used as a compromise - perhaps using a dovetail template for marking out.
When being cut by hand, there are two schools of thought as to whether the pins or the tails should be cut first. For pins first, the pins are laid out and cut by the chosen method, then the outline of the pins is transferred to the face of the tail board. For tails first, the tails are laid out and cut and then the outline is transferred to the end grain of the pin board. Each has advantages and it is a personal choice as to which is chosen.
Hand cut dovetails can often be distinguished from machine-cut dovetails by the width of the pins. It is possible to have pins that are almost triangular when cut by hand that are not possible when cut with a router, owing to the thickness of the router bit's shank. These narrow pins are known as London Pins.
The photograph at the top of this page shows a through dovetail (also known as plain dovetail) joint, where the end grain of both boards is visible when the joint is assembled. Through dovetails are common in carcass and box construction. Traditionally, the dovetails would have often be covered by a veneer. However, dovetails have become a signature of craftsmanship and are generally considered a feature, so they are rarely concealed in contemporary work.
A half-blind dovetail is used when the craftsman does not wish end grain to be visible from the front of the item. The tails are housed in sockets in the ends of the board that is to be the front of the item so that their ends cannot be seen.
Half-blind dovetails are commonly used to fasten drawer fronts to drawer sides. This is an alternative to the practice of attaching false fronts to drawers constructed using through dovetails.
The sliding dovetail is a method of joining two boards at right angles, where the intersection occurs within the field of one of the boards, that is not at the end. This joint provides the interlocking strength of a dovetail. Sliding dovetails are assembled by sliding the tail into the socket. It is common to slightly taper the socket, making it slightly tighter towards the rear of the joint, so that the two components can be slid together easily but the joint becomes tighter as the finished position is reached.