This section is from the book "A Practical Treatise On The Joints Made And Used By Builders", by Wyvill J. Christy. Also available from Amazon: Practical treatise on the joints made and used by builders.
Piecing Joint is one effected by a scarf for the purpose of adding a piece having the same cross section to the length of a timber or plank, or of bringing up the width and thickness of any part to that of the rest by the insertion of a piece. It is made as described under Scarf Joint.
Pinned Joint is a joint strengthened or fastened with a pin or key. This kind of fastening is of frequent occurrence in carpentry to hold a tenon in place. In order to make the contact between the shoulders of the tenon and the cheeks of the mortise as close as possible, the hole for the pin is bored so as to draw the tenon, and the operation, which is called drawboring, is performed by boring the hole in the first instance through the cheeks only, then inserting the tenon and marking the position of the hole, after which the tenon is removed and the hole bored, not, however, in the place marked, but a little nearer the shoulders, and when it is again inserted, a slightly tapering conical piece of steel, called a drawbore pin, is driven through the holes, forcing the shoulders close home. On removing the steel pin, the proper one made out of iron or hard wood, sometimes wetted, is inserted in its place. Its use in carpentry should be quite of secondary consideration, stability being secured without such an auxiliary, and consequently the practice of drawboring can be of no advantage, but rather the reverse in well-conditioned framing. The diameter of a wood pin should not be less than one-fourth the thickness of the tenon, and its position should be at a spot distant from the shoulders equal to one-third the tenon's length. In shape, it is either round, round with a square head, or square throughout, which is considered the best form, as it brings more of the wood into resistance, and is not so likely to cause splitting if its sides are properly situated with respect to the stress. In order to render it as effective as possible against shearing, it should be split off from a straight-grained piece. When the tenon passes right through the mortise, as shown in Fig. 47, or as in the somewhat similar case of framing a trimmer into a trimming joist, the hole is bored so as just to clear the mortise, and the piu is driven against the outside of the joist. The term tree-nail (pronounced trunnel) is restricted by some to large-sized pins, varying in diameter from 3/8 in. to ¾ in., and when of good English oak their resistance to shearing is about 2 tons per square inch of section.
Plain or Plane Joint is formed by the union or contact of two plane surfaces, as, for instance, when one piece of timber rests or beds upon, or abuts against, another, the area of junction being one and the same plane. It is characteristic of a fish joint. In common work, it is the usual mode of connecting joists to wall plates, rafters to ridge-pieces, etc, and usually a fastening of some kind is required to prevent sliding.
Post and Beam Joint occurs, as its name implies, between a post and beam, the latter being either inclined or horizontal, and either above or below the post. The points to be attended to are an equal and true bearing for the post, and the least possible diminution of strength in the abutment both of post and beam; and the choice of the best form of joint must in a great measure depend upon the nature of the load to be borne by the beam. In many situations the plan adopted in a common or proper door frame would no doubt suffice, viz., having a stub tenon at the foot and an ordinary one at the head of the post, whilst in others it would be preferable to cut a vertical mortise through the head and insert therein the tenoned end of the beam.