Manual of Purpose-Made Woodworking Joinery

Dovetail joints 43

Bridle joints

Figures 3.40(a)(b): These joints in their original, three-
layered form as illustrated, are traditionally known
as bridle joints – sometimes referred to as open- ended
mortise- and- tenon joints – but in their five- layered
form (or more), these framing joints are referred to as
comb- or finger- joints. The multi- layered comb joint
has a decorative appeal in presentday cabinetmaking
and is still used for jointing the framing members
of modern- style casement windows (as described
in Chapter 4). These joints are ideally made by a
machining process, but they are also quite easily made
by hand. The latter being a skill- challenge in ripping
accurately along the grain on the waste- side of the
multiple gauge lines.

Dowelled frame joints

Figure 3.41: Dowelled joints are often used as a sub-

stitute for mortise and tenon joints, but are generally

regarded as being inferior to them. And although I

am inclined to agree with this, I do so not because of

the joints failing structurally (this should not happen

if adequately- sized dowels are used; i.e. the diameter

should be approx two- fifths of the frame’s thick-

ness), but mainly because I have occasionally found

these joints failing via the glue being skimped in their

manufacture. Glue- skimping being more critical to

dowelled joints than to (wedged) mortise and tenon

joints.

Traditionally, these joints were always regarded as

being difficult to achieve by hand – and there were

two reasons for this. One being that the drill bit –

whatever type you use – tends to be taken slightly

away from its marked position when up against the

hard and soft fibres of the timber. The other reason is

that even with another person sighting the brace or

drill and advising you of its verticality (in two vertical

planes!), drilling precisely- positioned holes aligned to

the face side and at right angles to the edge, is virtually

impossible.

However, apart from modern, fixed machining-

processes, nowadays there is a variety of inexpensive,

patented dowelling jigs that can be bought. These are

clamped onto the work and the jig’s different sized

steel bushes keep the lip- and- spur bits in position

and at right- angles to the joint’s surfaces. Note that if

a frame, such as a small door, requires its inner edges

to be rebated, grooved or moulded, the holes for the

dowelled joints must be drilled prior to the edge treat-

ment.

Figure 3.39 Machine- made dovetails.

Figure 3.40 (a) Bridle joint (b) Comb- or finger- joint.

(a) (b)

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4

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4

Figure 3.41 Dowelled joint to top rail of rebated door;

note that the dowels’ depth. should be a half or two- thirds

the width of the stiles.