The butt-joint is employed when two pieces of wood are jointed together in the same plane. The simplest form is when the edges of the two pieces are brought together and held by glue, no other connecting medium being used. This is often sufficient, and when properly made is quite strong. It is almost invisible in the majority of woods when made so the grain is parallel with the line of contact.

When a stronger method is required, and one side of the pieces joined is hidden from view, blocks are glued across the joint, on the unexposed surface, so as to stiffen it. The grain of these blocks must be parallel with that of the jointed pieces that shrinkage may not loosen, or cause them to crack.

Another way of uniting the edges of two boards is by the tongue and groove. A tongue, or projecting piece, along the middle of the edge of one piece is matched to a groove in the edge of the other. Sometimes in place of this, a groove is cut in the edge of each of the boards throughout their entire length. Into these grooves is then glued a hardwood strip, called the tongue or slip-feather, uniting the two pieces.

The most popular joint with the cabinetmaker is the dowel-joint. It is perhaps the best where the wood is of sufficient thickness to permit its use. A dowel is a wooden pin used for fastening two pieces of wood together by inserting part of its length into one piece, the rest entering a corresponding hole in the other. Sometimes a number of dowels are fitted tightly into holes bored for them in one of the pieces to be joined, and the other has corresponding holes bored in it, in which the dowels also fit tightly when the two pieces are glued together.

Angle joints are frequently mitred; that is, the joined edges are cut at a bevel bisecting the angle between them when united. The union is made by butting the pieces and gluing them together. As this does not make a strong joint in itself, it is stiffened in various ways. One method is to drive small bits of corrugated metal in the ends of the pieces and across the joint, thus binding the parts together. At other times corner blocks are glued on the inner side of the mitred angle.

For rounded corners, or when a mitred angle is not wanted, the two pieces may be tongued and grooved together. The tongue is on the inner edge of one of the pieces, so that as much wood as possible is retained outside the groove on the other. The best and strongest method of joining two pieces at an angle is by dovetailing.

When the joint is made so the full thickness of each piece joined is visible and the shape of each dovetail can be seen, the joint is a plain dovetail. The lapped dovetail is constructed so the joint is seen at the side only, and is commonly used for fastening the sides and front of drawers together. When it is desirable to have all indications of the dovetailing hidden, a combination of the mitre and dovetail is used, in which the dovetails are cut in part of the thickness of the wood and the mitre in the remainder. Such a joint is a mitred dovetail.

The usual framing joints used by furniture makers are the dowel-joint and the mortise and tenon. (See also page 17.)

The true mortise (cavity) is cut near the end of one piece to receive the tongue (tenon) of the other. The tenon is not always the full width of the piece on which it is cut, but often is narrower.

When framing for a series of panels, a groove is sunk the whole length of two of the framing pieces (those extending horizontally, called rails), and those at right angles to them (vertical pieces between the panels, the stiles) have tenons cut on them which fit in the grooves. These grooves also receive the panels. This method avoids cutting a mortise for each tenon, and the name given to the joint is stub-tenon.

When two pieces are joined by cutting away half the thickness of each and then lapping them together, they are said to be halved. Such a joint is sometimes combined with a mitre, so that where exposed to view it appears like any mitred joint. It is then said to be halved-mitred.

Broad surfaces of casework are panelled partially as a means of decoration, but principally for constructive reasons. If the surface were made from a solid board, it would soon crack and warp as the wood became dryer. It might be built up and veneered as has been described for table tops (page 18), and this is occasionally done; but as paneling gives a change of plane with a chance for light and shade, it is more commonly used.

The panels are, however, veneered and cross-veneered on both sides of a core whenever perfect workmanship is wanted.

Panels are surrounded by a frame, which may be grooved to receive them; but a better way is to rebate the frame and hold the panels in by mouldings. Three ways of doing this are shown on Plate XIV. In the joiner's method either a groove is worked in the styles of the surrounding frame to hold the panel and then the moulding is placed in the angle against the panel, or a rebate is cut in which both panel and moulding are set.

In either case, if the moulding is nailed in, the nail will probably be driven directly in the panel, or else diagonally through both the edge of the panel and rail. In the first instance any shrinkage of the panel causes a crack to appear between the frame and the moulding.

To avoid this, a rebate can be cut in the moulding, when it is large enough to permit, so it will lap over on the frame a little and hide the joint.

But here, although (see illustration) the nail holds the moulding close against the frame, it also catches the edge of the panel and prevents it moving. The result is that cracks appear in the panel itself.

It does not improve matters much if the moulding is glued in, for the glue almost always binds both moulding and panel to the frame, so that a rupture will occur somewhere.