The Technique of FURNITURE MAKING

HALVED JOINTS

Several different forms of halving joint are used which are easy to cut and usually regarded as first exercises for students, although they have practical applications in skeleton grounds, frameworks, etc. In particular, the cross halving (140:1) gives a stronger connection than either tenons or dowels. Where the two pieces to be joined are of equal thickness, both halves or laps should be equal, the separate pieces clearly marked on the face and leading edge, and all gauging done from these, using the same gauge setting throughout so that the amount left in one piece (A) will equal the amount taken out of the other piece.

In working, the pieces should be positioned, marked in pencil either side, the cutting-lines squared across with a knife and the depths of the laps gauged in as described before. The shoulders are then sawn in on the waste, the waste chiselled away (140:2) from either side and finished off with a metal shoulder-plane. Edge cross halvings, i. e. halvings in the depth, are liable to fracture along the grain under any sudden impact, and an improved version is shown in 141:1 which prevents any side give, although some strength is sacrificed. 'L'or corner halvings (140:3) can be cut entirely with the small tenon-saw and, if accurate, can be assembled without further treatment as the slight ribbing of a fine saw will give a key for the glue. Figure 140:4 shows an oblique halving with the required angle set out with the adjustable bevel, and in 140:3, 4 both pieces can be left slightly full in the length and flushed off afterwards.

T halvings are constructed in the same manner as cross halvings, etc., and can be straight, or single dovetail taper (140:5) and double taper (140:6) to withstand a direct pull. The dovetail rake is marked out as described in Chapter 19, Dovetailing, with the slope set in a fraction from the top corner (140:5A) to give a seating for the saw. Figure 140:7 shows an oblique single dovetail taper housing often used in gallows brackets for shelving. Any pull in the direction of the arrows is protected by the shoulder X. A stopped version of the double taper used in connecting rails in table and carcass stands is shown at 140:6A.

Mitre halvings (140:8)

These are relatively weak as the gluing area is halved (140:8), and they are, therefore, confined to light frames where the strain is negligible or where the edges are moulded and
must show a mitre. Sash-bar halvings (140:9) are part cross halvings and part mitre halvings. The square recesses are cut first and the mitres after, using a mitre template for final trimming.

All halvings are glued, some can be screwed for additional strength, as shrinkage is bound to occur across the width, with rupturing of the glue-lines if the sections are wide.

BRIDLE JOINTS, ETC. (141)

Angle or corner bridles (141:2) are sometimes referred to as 'slot'/'open' mortise and tenon joints, and procedure is virtually the same as for tenoned work. They must be marked out with a mortise-gauge, working always from the face sides, and set to give a slot about one-third the total thickness, with equal substance left on either side. They are stronger than the corner halving as the gluing area is doubled, and the stout shoulders take the strain. 'T' bridles (141:3) form a stronger connection than 'T' halvings, and are the usual method of connecting middle legs to continuous top rails, where two short tenons would have little strength. If the top rail is thinner than the legs, the mortise-gauge must be reset accordingly (141:4), and if the rail is curved then a flat must be formed on the face of the rail so that the gauge works parallel. In cutting the slots it is quicker to saw the shoulders down to the full depth, bore a hole with brace and bit through the waste from either side (141:6) and finish off with a chisel. The slots are usually cut first and the tenon part cut and pared to fit, for it is easier to chisel across the tenon than to pare down vertically in the slot. Skew rails (141:7) cannot be bridled, and must be notched in and glue blocked from behind as shown. The rails can meet square at A if preferred.

Mitre bridles (141:5) are useful in framed-up work, mirrors, etc., and form a strong joint. Any moulding or rebating to the frame must be done first before the tenon and slot are cut. A stopped form is shown at A which is more delicate but not so strong.