Part 6

Fig. 93 shows the end view of the ordinary 7/8-in. "Tongued and Grooved Flooring board," as used in the construction of floors for mills, workshops and cottage property. This type of flooring is nailed to the joists in the ordinary manner, no attempt being made to conceal the nails used.

Fig. 94 is a section of flooring which is generally made of hardwood, such as maple, oak, or jarrah. It is used in positions such as ballroom and skating rink floors, etc., the tongue and groove being worked in such a manner that the joint covers the nails as shown. Each nail is driven into its position at one edge of the board, the groove holding the next board and hiding the nail (Fig. 95).

Fig. 96 shows an example of matchboarding known as "Tongued, Grooved and Beaded" on one side only, and Fig. 97 shows a similar type tongued, grooved and beaded on both sides. This variety of matchboarding is known in the trade as "T. G. and B." It is used for nailing on framing to form partitions for rooms, offices, etc., for panelling corridors, etc., and for making framed and ledged doors, building tool houses, cycle sheds and other outhouses.

Fig. 98 is an example of matchboarding that is tongued, grooved and vee'd on one side, and Fig. 99 shows tongued, grooved and vee'd both sides. These are used for similar purposes to Figs. 96 and 97, and many prefer the V matchboarding variety because it is more easily painted than the beaded variety.

The object of working a bead or beads on matchboarding is to break the jointing of the various pieces and to aim at ornamental effect; also to prevent unsightliness should the timber shrink slightly. When a moderate amount of shrinkage takes place, as is nearly always the case, the joint at the side of the bead appears to the casual observer to be the fillet or channel worked at the side of the bead. If the tongues are not painted before the work is put together, the shrinkage will cause the raw wood to show and thus make the joint too much in evidence.

Fig. 100 shows a "Double tongued and grooved" joint used in the wholesale cabinet factories. It is preferred for the jointing of cabinet stock, and the amateur can make a similar joint by working two grooves and inserting loose tongues.

Fig. 101 is the end view of a "Double-dovetailed, tongued and grooved" joint, and Fig. 102 is a sketch of a similar joint having only one dovetailed tongue.

From a constructional point of view Fig. 101 is far and away the best joint that has yet been produced. Unfortunately, however, there is not at the present time any hand tool that will economically produce it, owing probably to the fact that the joint is the subject of a patent. The dovetail tongue tapers slightly throughout its entire length, gripping the joint on the principle of the wedge and squeezing the glue into the pores of the wood.

CABINET-WORK JOINTS.--With regard to tongued and grooved joints which apply more particularly to the jointing of cabinet work, Fig. 93 is produced by planes which are specially made for the purpose. One plane makes the tongue and another the groove. The handiest sizes to buy are those which joint 3/8 in., 5/8 in., and 3/4 in. timber, it being usual to dowel or loose-tongue thicker boards. The 3/8 in. partitions (or, as they are sometimes called, dustboards) between the drawers of a sideboard or dressing chest are in good work jointed in this manner. The 5/8 in. and 3/4 in. ends and tops of pine or American whitewood dressing tables, wardrobes, etc., call for the larger sized plane.

LOOSE TONGUES.--There are two methods of jointing with loose tongues, viz., the use of the cross tongue, Fig. 103 A, and the use of the feather tongue, Fig. 103 B. Cross tongues are the stronger when glued in their position and can be used very much thinner than feather tongues. Feather tongues are cut diagonally across the grain as illustrated.

Fig. 105 is a cradle for planing up loose tongues to the required width (generally 7/8 in.). Two grooves are made in a piece of 1-1/4 in. hardwood; one groove is used for planing the width way of the tongue and the other for planing the edge way. These tongues can be cut to accurate size on a circular saw bench if power and machinery are at hand.

APPLICATIONS OF THE JOINT.--Fig. 106 is a sketch of a portion of a sideboard top, showing the plough groove ready worked out to receive the tongue; the other half of the top is treated in a similar manner. It will be noticed that the groove is not worked through the full length of the board, but stopped about 1-1/4 in. from each end; this leaves a square joint at each end of the top on which the moulding is worked. If the groove be run through the board it looks very unsightly when the mould is finished.

Fig. 107 is a shaped spandrel, such as is fixed in the recess of a sideboard or cupboard or shop window fitment. It is of such a width that, were it cut from a wide board, the shaped portion would be apt to break off owing to the short grain at C. The shaping is therefore built up out of three separate pieces, the grain running as indicated. The loose tongue is represented by the dotted line and a section is shown of the joint at the line A B. At the opposite corner the tongue is left blind, i.e., not run through the edge. This is the method that should be used when the shaping is above the level of the eye.

Fig. 108 shows part of a carcase of a dressing table. The drawer runner A is shown grooved across the end to receive a cross tongue; this cross tongue engages a similar groove in the front bearer. This method of fastening the runner to the bearer is in everyday use.

Fig. 109 is a writing table top. The centre boards are first jointed and glued up, after which the ends and sides are grooved ready to receive the cross tongues. The hardwood margins are shown at one end and at the front, and the grooves are arranged so that, on completion, the marginal frame stands above the top just the amount of the thickness of the leather which will cover the table. In some cases the margin at the end runs the same way of the grain as the top, thus allowing for slight shrinkage. Cross tongues would of course be used in this case.

Fig. 110 is a sketch showing one-quarter of a barred or tracery cabinet door. An enlarged section of the astragal mould which is grooved to fit on the bar which forms the rebate is also shown.

Fig. 111 is a "Combing or corner locking" joint, a method of making boxes by means of a continuous use of tongues and grooves instead of dovetails. This type of joint is generally machine made. The amateur, however, who is not proficient to undertake a dovetailed box frequently uses this method.

CORNER JOINTS.--Fig. 112 shows both a single loose tongue and a double solid tongue. Both are methods used to connect circular cornered work, such as a counter end, to the front framing.

Fig. 113 indicates a tongued and grooved joint suitable for edge or end jointing, such as fitting matchboarding round a chimney breast, making small jewel drawers, etc.

Fig. 114 is a tongued and grooved joint with a bead worked on same to hide the joint, sometimes called a staff-bead. It would be used in positions such as boarding around an upright iron pillar, etc., the bead giving a neat finish at each corner.

Fig. 115 is a similar joint, but at an obtuse angle. An example of its use is in fixing boarding around an octagonal column of brickwork.

Fig. 116 shows a tongued and grooved mitre as used for strengthening the corners of cabinet work, such as tea caddies, small boxes, plinths, etc. Two pieces of wood are glued in position and allowed to set prior to glueing and cramping the joint proper. These pieces are afterwards planed away, thus leaving a clear surface to the box sides.

Fig. 117 shows the method of working the groove in the above joints. The pieces are turned back to back, the mitres thus making a right angle. The guide on the grooving plane thus works against each face of the joint, and this ensures correct jointing.

Fig. 118 is somewhat similar to Fig. 113, but with a quarter circle mould to hide the joint.

Fig. 119 indicates the building up of a double skirting mould. C represents the brickwork, A the oak-framed panelling, and B the packing and fixing block. A wide skirting of this type is made in two portions for convenience in working the moulding and to prevent undue shrinkage.

Fig. 120 illustrates the use of a tongued and grooved joint for fixing together the sides of a corner bracket, and the same method holds good when jointing a corner cupboard. A capping mould or top shelf will conceal the joint; it then has the appearance of a glued butt joint, but is of course considerably stronger. No screws or nails are required if this joint be used.

PLOUGHING.--When grooves have to be worked in the edge or face of a board to receive tongues, the process is generally called ploughing, and it is usually accomplished by a special tool called a plough (or, as it is occasionally spelt, "plow"). When a plough plane is bought it is usual to procure eight plough bits or blades of various sizes to fit the plane. In Fig. 121 is given the sketch of a plough plane with the names of the various parts lettered thereon.

The board or boards which it is desired to groove are first planed straight and true, exactly as though it were desired to make a glued or butt joint. One of the boards is now placed edge way up in the vice and with the face side to the worker.