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.
| Fig. 136.—Cutting Wedges from Waste of Haunching. | 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 illustration shows the method of tenoning the three pieces to the top rail, barefaced tenons being employed.
| Fig. 138.—Joint used for Garden Gates. | Fig. 139.— Sprocket Wheel. | 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 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.—Method of Fitting an Interior Table Leg.
| Fig. 142.—Haunched Tenon for Skylight or Garden Frame. | Fig 143.—Long and Short Shouldered Tenon. |