Abutting Joint

This is common in carpentry, and occurs whenever the end of one timber or piece is adjusted to bear upon any part of another, either for support or for prolongation or continuation. The end may be either cut or left square, and may simply rest upon the other piece, or be framed, or in any way joined to it. The junctions of different lengths of wall plates, of principal rafters with tie-beams and posts, and of binders with girders afford familiar examples, whilst the ends of shores and rakers resting against needles at one extremity and the footing piece at the other equally well exhibit the same kind of joint at the surfaces pressed by the abutments. It is worth observing that the end of a piece of timber when cut and shaped or otherwise arranged to fit against another piece to form a joint is called its abutment, and since the direction of the action of butting timbers upon each other is perpendicular to their abutments, these should be cut as nearly as circumstances will permit at right angles to the lines of pressure. The form of abutment, however, affects only the distribution of strain about the bearing surfaces and the strength of the joint, and not the intensity of the pressures transmitted through and along the timbers.

Adjustable Joint

Adjustable Joint is usually formed with gibs and cotters, as explained further on, for the purpose of tightening up the tie-beam to the king-post after the roof has taken its bearing. Sometimes the principal rafters are similarly united to the head of the post to bring the members of the truss close up to their seatings after settlement and shrinkage.

Angle Joint

Angle Joint is formed when the ends of two timbers or pieces meet at any angle with or without interpenetration. A butt and mitre between a strut and straining piece, or block, as in Fig. 63, p. 107, forms a good example. In old half-timbered houses, instead of joining the sills, and thereby weakening the corners with angle joints, angle posts were let into the ground to receive the tenons of the sills, and a short raking strut inserted 'twixt post and sill to take the strain off the tenon, as shown in Fig. 52, p. 97. In log huts, angle joints are formed by notching, as in Fig. 24, or else by halving and pinning. If squared, the logs may be dovetailed or halved.

Angular Joint

Angular Joint is one requiring one of the pieces between which it occurs to be cut to an angle, and is illustrated by a bridle joint or a joggle, or a birdsmouth as represented in Fig. 25.

Angular Grooved And Tongued Joint

This is a similar joint on a larger scale to that described in Section VIII. It is used sometimes to help to render sheet piling water-tight when the piles take the form of planking about 4 in. thick.

Banded Joint

One strengthened by a wrought iron band or strap, usually in duplicate on opposite sides, and bolted through together. Angle bands between struts and beams sometimes cause fracture through the strain being transferred from the timbers to the bolts, and acting with the leverage of one of the timbers, and frequently with that of half the beam.

Banded Joint 25

Fig. 24.

Banded Joint 26

Fig. 25.