T-heads are planed while the rods are situated as denoted in Fig. 748, after the intermediate portions are lathe-turned. The holding plates are placed across the rods, having either emery-cloth, canvas, or leather, in immediate contact, to avoid bruising the turned surfaces. The two planed surfaces of each head are made equi-distant from the centre, by means of a circular line marked on the turned extremity, which line is seen in the Figure, on one extremity of each head. In some cases, the planing of such heads is conveniently done while the brasses, cap, and connecting-bolts are attached to the rods' heads, the bolts being used to tighten the brasses between the cap and head. When this plan is adopted, the bolt-holes in the head, cap, and brasses are finished, and the bolts also fitted, that when all are tightened together, each portion shall be in its required position. The planing of the T-head edges of the brasses and the cap can now be done at one fixing of the rod. Such planing is done previous to boring the middle hole of the brasses, and lathe-turning the outsides of the ridges; consequently, at the adjusting for boring the middle hole, the planed edges of the brasses are the portions which are put upon parallel blocks, in order to place the planed edges parallel with the chuck, and thereby to cause the hole to be bored at right-angles to the length of the connecting-jod as desired.

Gap-end connecting-rods are those having semi-cylindrical gaps in their heads, to contain half-round brasses, instead of having flat-bottom brasses. The planing of a gap-end resembles that for a T-end, the bolt-holes being finished, and the bolts fitted, that the cap may be connected and planed with the head. A gap-end rod which is forged solid with its cap, or with its two caps, is planed on both the broad sides of its heads previous to boring the middle hole, the bolt-holes, and separating the cap with a parting tool or saw. During all planing of gap-end rods and T-end rods the intermediate portions should be in contact with vee-blocks, in preference to other packing. The rod should rest on canvas or leather in the vee-notches ; and several parallel blocks may be put beneath the vee-blocks, if necessary, to place the rod high enough from the table to allow it to be swung around its axis.