There are two vertical boring mills used for cylinder work, one being capable of boring up to 120 in. in diameter, and the other to 94 in. in diameter. A combined boring and facing machine, with a table 4 ft. square, is usefully employed on propeller bosses, valve-chests, small cylinders, and built-up bed-plates, machine bearings, etc.
The installation of high-speed lathes is specially noteworthy. In one, the face-plate can take in 12 ft. in diameter, and, as the length of bed is 30 ft., it is useful for large surfacing work, as well as for turning crankshafts of the larger sizes. There are two 12-in. double-geared lathes for surfacing and screw cutting. These are self-acting, and the lengths of bed are 19 ft. and 12 ft. respectively. For turning piston and connecting rods, two screw-cutting lathes of 16-1/4-in. centres are in use, the length of the bed being 22-1/2 ft. These have each a triple-gear headstock, and a chuck 48 in. in diameter; with rack motion and slide-rest feeds. A 20-in. centre lathe, with a bed 28 ft. 6 in. long, is fitted with two saddles and four slide-rests for shaft liners, etc. Amongst others, there is a 27-in. centre lathe for shafting, the bed being 36 ft. long.
One of the lathes is illustrated on Plate LI., adjoining page 109. This is a 48-in. surfacing and boring lathe, by Messrs. John Lang and Sons, Limited, Johnstone. The two new features introduced are the variable speed drive and automatic speed-changing mechanism. The headstocks can be used for single or triple gear, and are so arranged that, even when running at the greatest speed, there is a reduction by gearing. With this arrangement the lathes have greater power when turning small diameters than when the belt is used driving direct to the main spindle. The spindles, which are hollow, with hexagonal turrets, are of crucible cast steel, and run in gun-metal bearings. By means of the speed-changing mechanism, the cutting speed of the tool is kept practically constant when surfacing. This means that any surface can be finished off in about one-half of the time taken by a lathe having the ordinary step-cone drive, where the workman will not change the position of the belt while surfacing. The self-acting feed-motions are positive.