(116) The flats are made of a =T= section for the greater part of their length, but have flat surfaces formed at each end, as shown in Fig. 51. On these surfaces they travel, and are sustained in their course by the bend. The width of each flat is usually from 1-1/8in. to 1-3/8in.—the narrower ones being generally preferred—and the length varies with the width of the cylinder. The underside of each flat is made quite level, in order to afford a surface from which the various mechanical operations can be conducted. As the wire clothing is fastened to this face it is obvious that, by making it the base of all subsequent treatment of the flat, a decided advantage is obtained. The first operation is that of milling two surfaces at the upper side of each end of the flat, at the same time trueing up the faces of the ears to which the chain is attached. A double-ended machine is used, fitted at each end with an instantaneous grip chuck, at the bottom of which is a steel face on to which the ends of the flat are placed, the flat having been previously stretched and straightened. The flat is then cramped down, and the cutter brought into operation. The flat is placed on the faces thus formed in the next machine, which is constructed with chucks at the end of two long radius arms. A cross spindle has a worm fitted on it, which gears with a segment at the end of the arms, and by revolving which the flat is brought under the cutters, and has a hollow cut into it of the desired radius. The flat is then chucked edge up and milled by a cutter on its upper side at the ends, so as to provide the necessary clearance for the chain. The next operation is to cut out, by means of a similar machine to the one with the long radius arms, the under surface of the flat end, which had been treated by that machine, so as to leave two surfaces on which the flat travels, the radius arms in this case being shorter. These surfaces have two objects—to lessen the friction when the flat is travelling, and to allow of the flat having the necessary heel given to it. The flat is then cramped down on the surface thus formed, and the snugs are drilled by a double-ended machine fitted with an automatic motion for withdrawing the drill. By the same machine the hole is tapped, the tap reversing when it has gone the requisite depth. After drilling the flat along the edges in order to enable the clothing to be fastened, it is complete so far as its treatment by machines is concerned.