The Technique of FURNITURE MAKING
Miscellaneous tenons
Figure 146:2 shows the single stub tenon for connecting drawer rails to carcass sides, but the length of the tenon can only be a bare 1/2 in (12.5 mm) in a 3/4 in (19 mm) carcass cheek, and double tenons are better (146:3). For instance, two 5/8 in (16 mm) wide tenons spaced apart 3/8 in (9.5 mm) in a 21/4 in (57 mm) wide rail offer nearly twice the gluing surface as compared with a single I1/4 in (32 mm) wide tenon; moreover shrinkage is less. Figure 146:4 is a mitre shoulder tenon useful where a rail meets a leg or post on a curve which would result in a feather edge at the springing-line if the normal type of square shoulder were used (see also Leg and frame construction, Chapter 22). The joint is first cut as an orthodox mortise and tenon joint, allowing about 1/4 in (6 mm) of shoulder below the tenon for the mitre cut, and the sloping shoulders are then laid out and cut. A square shoulder terminating in a mitre cut can be used instead of the sloping shoulder, the only difference being in the appearance. The curve to the rail can be cut beforehand, but sufficiently full to allow final shaping to the exact curve after the rails have been fitted. Figure 146:5 is the tongued shoulder tenon useful where a heavy tenon is set back, leaving a wide shoulder; while 146:6 are twin tenons for heavy work which give a more secure fixing without taking out too much strength in a single wide mortise. Figure 146:7 shows pinning used for short uprights or divisions between drawer rails, and for partitions in large carcasses; the tenons can be wedged as shown if necessary. In modern work pinning tenons are often dispensed with, and the upright is housed/ dadoed and screwed from above, but where the rail below has to take transmitted weight, wedged pinning tenons are better.
Figure 146:8 is a false tenon either slotted or mortised into wild grain which has little intrinsic strength; it is also useful in repair work where the original tenon has snapped off, and provided it is tightly fitted there is little difference in the ultimate strength. Figure 146:9 shows the carpenter's draw bore tenon sometimes used in reproduction oak-work. The joint is cut in the usual manner, the tenon withdrawn and a waste piece slipped into the mortise socket; the hole for the pin is then bored through, the waste piece withdrawn and the tenon pushed home. If the same bit is fed through the hole to prick a position-mark on the tenon, and the mark is then moved about 1/16 in (1.5 mm) up and in towards the shoulder (A), a hole bored through the tenon will be slightly offset and will pull the parts together when a tapered drive pin is driven through the joint. Draw boring can be used in corner bridles or open slot tenons, and is an excellent way of securing these joints. Figure 146:11 is the fox wedged tenon in which the wedges are placed in position as shown, and driven in as the rail enters. This joint is of, academic rather than practical interest; for if the undercutting of the shoulders of the mortise socket is too great the joint will be slack, or if not enough, then the wedges will not fully enter the saw kerfs, and will prevent the tenon from fully entering. Figure 146:12 is the combined bridle and tenon which is useful for long tables with intermediate legs and continuous rails. The position of the joint can be reversed to show either the rail butting against the leg on either side, or passing over the leg in an unbroken line. Figure 146:10 shows double tenons used in wide rails or narrow carcass cheeks into legs or posts, and divided, as shown, to counteract the inevitable shrinkage of a single wide tenon. This type is no longer used to any great extent in modern furniture, in which a continuous tongue in a shallow groove is usually sufficient to hold the joint.
