This machine, shown in Fig. 201, is used for boring large steam cylinders, gun-hoop forgings, locomotive drive-wheel tires, fly wheels, and similar large work. This work may also be faced or turned on the ends, just as can be done on the face plate of a lathe.

Work to be turned or bored is clamped on the heavy revolving table T, which revolves on a vertical axis. This table is virtually a face plate, as on the lathe. The housings HH of the machine, and all the fittings they carry, are for holding rigidly and governing the movements of the cutting tools. A tool is clamped in each of the holders BB on the tool bars CC, and both tools may be fed independently in a vertical, horizontal, or slightly inclined direction as desired. Either tool may cut inside, outside or on the upper end of a piece of work.

The tool bars may be inclined about 30° on the swivel head DD, and these heads are readily adjusted along the cross rail RR. The cross rail is readily adjusted vertically along the faces of the housings. The tool bars are raised or lowered by the hand wheels on the swivel heads when adjusting them for cutting operations.

They are made very heavy for rigidity and their weight is counterbalanced by a heavy weight on the ends of the chain K.

The mechanism on top of the machine adjusts the various parts preparatory to operating the machine, and the feed mechanism at the right controls the feeding of the tools while they are cutting. The machine is driven by a motor not in view.

Fig. 201. - Vertical Boring and Turning Mill.

Some designs of this machine are fitted with equipment and attachments, not here shown, for many varieties of machining, increasing its usefulness particularly in saving time required to shift a heavy cylinder to another machine and adjust it thereon.