Part 7

Take the plough plane and select a suitably-sized blade; fix it in the plane in the usual way, allowing the cutting edge to project beyond the steel skate about 1/32 in., and securely drive up the wedge. Next loosen the small boxwood wedges at the side of each stem, and adjust the plane by tapping the stems with a hammer until the cutting iron is in the desired position; then knock up the small wedges nice and tight. When setting the fence to or from the blade it is a wise precaution to measure the distance from the fence to the skate at each end of the plane; this will ensure the skate being parallel to the fence. The neglect of this is a source of annoyance to many amateurs. Now adjust the depth stop by turning the screw at the top of the plane, measuring the depth of the required groove from the edge of the blade to the stop, and carefully lock the screw which adjusts this stop.

The plane is now ready for use. Hold the fence close up to the side of the timber, the hands in position as shown at Fig. 122, the position of the body being that generally assumed in planing. Move the plane backwards and forwards in the usual manner, beginning the cut at the end of the board nearest to the vice jaws (the front), and proceed with the planing until the depth stop is in contact with the wood. Then take a step backwards and repeat the process until the whole length of the groove is ploughed. Care must be taken to force the fence up to the board with the left hand, whilst the right hand thrusts the plane backwards and forwards, and the plane must be kept vertical.

TONGUEING.--The grooves having been completed, the tongues have to be made. Fig. 123 shows a sketch of a board and the method of marking out cross tongues (A) and feather tongues (B). The usual procedure for making cross tongues is to plane the end of the board and use a cutting gauge to give a line the required distance from the end (see sketch). The board is sawn with a tenon or panel saw, and the piece of timber for the tongue is thus procured. If a feather tongue is to be used it is cut diagonally from the board (B) and the ends cut square as shown by the dotted line.

Feather tongues can be obtained in fairly long lengths out of narrow boards, whilst on the other hand cross tongues are limited by the width of the board. After cutting off the tongues, they require planing with nicety to fit the grooves, and the advantage of a grooved board (Fig. 105) will be appreciated. A glue spoon similar to a plumber's ladle is generally used to pour the glue into the grooves, and it is customary to glue the tongue into one board first; after allowing this to set, the joint is completed in the usual manner.

TONGUEING PLANES.--Fig. 124 shows the end view of a tongueing plane for working matched joints out of the solid. The method of holding and using the plane is similar to the directions given for using the plough. The part lettered F (in front) represents the fence, which in this case is not adjustable.

In description Fig. 125 is similar to Fig. 124. The steel skate runs in the groove and supports the cutting blade similar to that in the plough plane, and provided a grooving plane of this type is of suitable width it may be used for making grooves for loose tongues. There is on the market a metal plane which is specially designed with handles at both ends. This plane carries a grooving iron on one side and a tongueing iron on the other side; thus with one plane both the tongue and the groove can be worked.

Fig. 126 shows the method of tongueing the shoulders of tenons as used in thick timber which is to be veneered on the face. A temporary piece of wood (A) is put between the tenon cheek and the saw, thus forming a guide for the latter. After cutting one saw kerf a thicker piece is made and a second saw kerf cut; the waste between the saw kerfs is now removed with an 1/8 in. chisel and this completes the groove. A tongue of this type acts as an extra tenon and prevents the joint from "lipping" (becoming uneven) on the face side.

THE MORTISE AND TENON JOINT

A mortise and tenon joint is the method of joining timber by working a solid rectangular projection in the one piece and cutting a corresponding cavity to receive it in the adjoining piece. The projection is called the tenon, and the cavity the mortise. Joints of this type are secured in various ways. Small wedges, wooden dowels, metal dowel pins, glue and paint are frequently used, and prior to the introduction of glue we have examples of Egyptian furniture in which the mortise and tenon joints were united by a composition of cheese.

BAREFACED TENONS.--Fig. 127 illustrates the joint in its simplest form and shows a tenon having only one shoulder. This is called a barefaced tenon, and it will be noticed that the portion which carries the mortise is thicker than the rail on which the tenon is cut. The joint is therefore level (or flush as it is called) on one side only, and it should never be used at the corner of a frame. It is a useful interior joint for framing that has to be covered on the back side with matchboarding, and allows the work to finish level at the back when the boarding has been applied (see plan, Fig. 127).

STUB OR STUMP TENON (Fig. 128; also occasionally called a joggle tenon).--The illustration shows a tenon as used in the interior of a frame. The tenon is not allowed to run through the stile, and unsightliness on the edge is thus avoided. This type of tenon is often used at the corner of a frame, and it then requires to be haunched. A good workshop method of gauging the depth of the mortise for a stub tenon is shown in Fig. 129; a piece of gummed stamp paper is stuck on the side of the mortise chisel, indicating the desired depth of the mortise. This greatly facilitates the work, as it is not necessary to be constantly measuring.

A HAUNCHED TENON as used at the end of a door frame is shown at Fig. 130.--In this case it will be seen that the width of the tenon is reduced, so that sufficient timber will be left at the end of the stile to resist the pressure of the tenon when the joint is driven together. The short portion (A) which is left on the tenon is called the haunch, and the cavity it engages is termed the haunching. The haunch and haunching prevent the two pieces of timber lipping, or becoming uneven on the face side, as would be the result if it were cut away entirely up to the shoulder.

Fig. 131 shows the type of tenon and haunch used when the stile or upright rail is grooved to receive a panel. In this and similar cases the haunch is made the same width and the same depth as the groove; the groove therefore acts as the haunching. An application of this joint is shown in the top rail of the door frame, Fig. 132.

This type of joint is also used to connect the rail to the leg of an ordinary kitchen table (see Fig. 167).

Fig. 133 is a variation of the stump tenon, occasionally used where the work in hand demands a thin tenon and a stout stump to take heavy strains.

A joint used for inside framing is seen at Fig. 134. The rails may be used as shown, but in the case of a door frame (as Fig. 132) they would have the inside edges grooved to receive the panels; the tenons would therefore be slightly narrower than shown, owing to the groove at each edge.

A HAUNCHED BAREFACED TENON, used in similar positions to Fig. 131, is shown at Fig. 135. The door or frame in this case would be made of matchboarding nailed on the back as shown in the plan at Fig. 127.

WEDGES.--Fig. 136 shows the method of cutting wedges which are to be used to wedge the tenons; this avoids waste of material. Some workers cut the wedges from the pieces left out of the haunching of the lock rail, or the bottom rail.

A STILE AND CROSS RAIL, framed together, are shown at Fig. 137. The portion above the rail is called the horn, and it is usual to leave sufficient length of stile to project above and below the cross rails, so that there will be no tendency for the stile to burst out at the end whilst the cramping and wedging of the frame is in progress. On completing the framing the horn is cut away.

In Fig. 138 we have a type of joint frequently used for garden gates. The illustration shows the method of tenoning the three pieces to the top rail, barefaced tenons being employed.

SPROCKET WHEEL.--At Fig. 139 are shown the guide bar and chain of a chain-mortising machine, two enlarged links of the chain being indicated at A. The chain is similar in construction to the driving chain of a bicycle, with the exception that it is provided with teeth which cut away the timber as the chain revolves. When using a chain mortiser the portion of the machine carrying the chain is fed downwards into the timber, thus cutting a clean and true mortise. If, however, a stump mortise is required it is necessary to pare away a certain amount of timber by hand, because the machine obviously leaves a semicircular bottom to the mortise. To overcome this difficulty the latest types of mortising machines have a square hole-boring attachment fixed alongside the chain. This tool, the working portion of which is illustrated in Fig. 140, consists of a square hollow chisel (E), which is sharpened from the inside, and a revolving twist bit (D) fitted with spurs or nickers, but without a point (one spur can be seen at the bottom of the illustration). This bit revolves inside the shell like a chisel, and bores away the superfluous timber, whilst the pressure exerted on the chisel causes the corners to be cut away dead square. A mortise 3/8 in. square by 6 ins. in depth may thus be cut. The portion marked A is the shank of the chisel (Fig. 140), where it is fixed into the body of the machine, and the hole at E allows the boring bit to free itself.

Fig. 141 indicates the method of fixing an interior leg to a table having a circular or straight top rail. The inlaid leg in this case is stump-tenoned into the top rail, and the inlaid portion of the leg is allowed to run through the rail, thus giving continuity of design.

Fig. 142 shows the application of the haunched tenon (Fig. 135) to the making of a skylight or garden frame. In this and similar cases the side rails are rebated as shown in the section, and the bottom rail is thinner than the side rails to allow the glass to finish level upon it.

LONG AND SHORT SHOULDERED JOINT.--Fig. 143 shows a haunched mortise and tenon joint having a long and short shoulder. This is a fairly common joint in framed partitions for offices, framing for greenhouses, tool sheds, etc., and is a frequent source of annoyance to the amateur. It is necessary to use this joint when both the stiles and uprights are rebated, and it calls for accurate marking out and great care in the making.

Fig. 144 shows the upright and rails of common garden or field fencing. The tenons are bevelled to fit and wedge each other in the mortise. The illustration gives both cross rails as shouldered, but in many cases shoulders are omitted when the rails are not thick enough to carry them.

Fig. 145 indicates faulty methods of working a tenon. At A the saw has been allowed to run too far when cutting the shoulder, thus greatly weakening the tenon. At B faulty sawing has again occurred, and to remedy this defect the worker has resorted to paring the shoulder with a chisel. Had the chisel been used vertically an undercut shoulder (as at B) would not have occurred. The trouble now is that the slightest amount of shrinkage in the width of the stile will show an open joint. The result will be the same if it is necessary to remove a shaving or two when planing or levelling up the face of the frame.

A JAPANESE TENONED JOINT, little known and rarely used in this country, is shown at Fig. 146. For clearness the two parts are here shown separate. The joint is self-wedging and will be of interest to Handicraft Instructors.

A TENONED AND SCRIBED JOINT is seen at Fig. 147. The cross rail is cut at the shoulder, so as to fit the moulding which is worked on the stile. This is a good joint in everyday use.