Part 6 (1/2)

[Ill.u.s.tration: Fig. 133.--Occasional Stump Tenon.]

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.

[Ill.u.s.tration: Fig. 134.--Joint for Inside Framing.]

[Ill.u.s.tration: Fig. 135.--Haunched Barefaced Tenon.]

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.

[Ill.u.s.tration: Fig. 136.--Cutting Wedges from Waste of Haunching.]

[Ill.u.s.tration: Fig. 137.--Stile and Cross Rail with Horn.]

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 ill.u.s.tration shows the method of tenoning the three pieces to the top rail, barefaced tenons being employed.

[Ill.u.s.tration: Fig. 138.--Joint used for Garden Gates.]

[Ill.u.s.tration: Fig. 139.--Sprocket Wheel.]

[Ill.u.s.tration: Fig. 140.--Boring Tool.]

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 ill.u.s.trated 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 ill.u.s.tration).

This bit revolves inside the sh.e.l.l 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.

[Ill.u.s.tration: Fig. 141.--Method of Fitting an Interior Table Leg.]

[Ill.u.s.tration: Fig. 142.--Haunched Tenon for Skylight or Garden Frame.]

[Ill.u.s.tration: Fig 143.--Long and Short Shouldered Tenon.]

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 gla.s.s 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 part.i.tions 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.

[Ill.u.s.tration: Fig. 144.--Joint for Fencing.]

[Ill.u.s.tration: Fig. 145.--Example of Faulty Tenon.]

Fig. 144 shows the upright and rails of common garden or field fencing.