Manual of Purpose-Made Woodworking Joinery

34 Joinery joints

The technique can be applied to setting out either
through- dovetails or lapped- dovetails.

Dovetailing terminology

● Dovetails: The double- slope shapes on the face-

ends of the material, likened to the appearance of a

dove’s fan- shaped tail

● Dovetail sockets: The double- slope recesses on the

end grain of the material, cut away to receive the

dovetails

● Normal pins: The double- slope, inverted dovetail

shapes separating the sockets and locking (pinning)

the dovetails into them

● Half pins: The single- slope, inverted half- dovetail

shapes positioned on the outer edges of the timber

(note that they are always referred to as half pins,

even though they are usually larger than an exact

half division of a normal double- slope pin)

● Pin sockets: The double- slope, inverted dovetail

recesses between the dovetails, cut away to receive

the pins.

Traditional method

Figure 3.25: The traditional technique of setting
out sets of dovetails with a rule also conforms to a
simple method of geometry. Such a method avoids
mathematical division of the actual width of the
timber to be divided for a number of dovetails and
adopts suitable non- fractionized units that, when

multiplied by the chosen number of dovetails, must

always be greater than the actual width of the timber.

As illustrated in Figure 3.25, the number of oversized

units (multiples of 40mm in the example) shown on

the rule is equal to – and decided by – the number of

dovetails you choose to use on a particular width of

timber. However, bear in mind that the dovetails –

for shrinkage reasons – should not be wider than

38mm at their base. With repetition and experi-

ence, the amount of dovetails required can usually be

visualized.

By this method, once the shoulder lines (equal

to the wood’s thickness + 1mm for initial end-

grain planing and eventual cleaning up) have

been pencil- marked squarely around the timber to

be dovetailed, you must first decide what size the

widest part of the normal pins will be. It is wise to

make them slightly larger than one of your bevel-

edged chisels. This will simplify the eventual vertical

paring of the waste material against the shoulder line

of the pin sockets. In this example, I have chosen

14mm to suit a 12mm (or ½”) chisel. Then halve this

chosen measurement and pencil- gauge a 7mm (or

¼”) line along the face- side of each outer edge, as

illustrated.

Next, lay a rule across these outer- edge lines and

pivot it as shown until the multiple of your chosen

units (40mm × 4 (for number of dovetails) = 160mm)

is shown between the lines. Carefully mark the

three points given at 40mm, 80mm and 120mm, as

these will be the centres of the normal pins. Produce

pencil- gauged lines from these three points up to

the shoulder line, then mark 7mm points on each

side of these lines from which to mark the slopes of

the pins and tails.

Normal pin

Half pin

Figure 3.24 A set of four through- dovetails.

14 14

7 7

Figure 3.25 Traditional method of setting out dovetails.