Manual of Purpose-Made Woodworking Joinery

Edge joints 49

When manufactured, the elliptical- shaped biscuits
are pressed and cut to shape from feather- grained
beech and come in two sizes; feathered- grain is a tra-
ditional technique of arranging the grain at 45° across
the face of the timber. This is done to eliminate the
risk of the thin biscuits splitting along the grain when
positioned midway within a joint. The grain direction
is indicated in the illustration above.

Loose- tongue jointing

This traditional tongue- and- groove method of rein-
forcing and aligning edge joints, again follows the
basic procedures for preparing the edges. Then each
edge is grooved throughout its length to receive a loose
(i.e. separate) tongue and, when gluing the edges, this
is glued into the grooves prior to cramping up.
The grooves can be cut on the following machines:

1. a circular saw- bench (if the saw’s spindle can be
   lowered enough); 2) on a spindle moulding machine
   with a so- called wobble- or drunken- saw; 3) with a
   portable powered router – or 4) even on a biscuit
   jointer used as a mini portable- saw. An advantage
   with the last three methods mentioned, is that stopped-
   grooves can be made near each end if a concealed
   tongue is required for aesthetic reasons on a particular
   job. But if none of these fixed- or portable- machines
   is available, the grooves can be done by hand with
   a metal plough plane. For small jobs, I use either a
   Record 050 plough plane or a far superior Stanley 45
   combination plane.
   The main skill element in using plough planes is to
   do with keeping them in a constantly vertical position
   whilst planing. Starting at the front of the timber, the

plane is worked regressively backwards until an initial

shallow groove is established. Then the end- grain

appearance of the groove should be checked before

proceeding, as this will reliably indicate whether you

need to adjust the lean of the plane to achieve verti-

cality. Although the fence of the plane is held tightly

against the face side of the timber when the plane is

being used – which should keep the groove upright –

in reality the plane can develop a lean to one side or

the other.

Traditionally, the loose tongues were made from

selected timber to the thickness of the tongue

required. This critical size was checked with a hand-

made gauge called a mullet – which was a small offcut

of timber (about 200mm long) with the required

groove run in it to act as a gauge when slotted onto

the tongue- material to test its thickness. The aim was

to achieve a snug fit, not too loose and not too tight.

Types of tongue

Figures 3.50(a)(b): Once the snug fit was achieved,

the material was cut to the width of the tongues

required. Two types were used, as illustrated; one

being cross- grained, whereby the grain ran at 90° across

the tongue’s width – at right angles to the joint line.

The other being feather- grained, whereby the grain

(as explained in biscuit jointing) ran at 45° across the

tongue’s width – at an acute angle to the joint line.

Both of these methods gave greater resistance to

any side pressure applied to the made- up tongued

joint, but the feather- grained – by being cut at 45°

across the grain – produced longer lengths of tongue

from relatively narrow, pre- thicknessed boards.

Long- grained tongues, where the grain runs length-

wise – parallel to the joint line – were reckoned to be

relatively less strong.

If the tongues being produced were not too thick –

say not more than 6mm – they were cut by setting

Figure 3.49 Open biscuit- jointed edges. Note that the
elliptical- shaped biscuit is positioned in the centre of the
segmental- shaped groove.

Figure 3.50 (a) Cross- grained tongue; (b) Feather-

grained tongue.

(a) (b)