The main types of modern lathes

The Automatic Lathe is so designed that all of the tool move­ments are automatically controlled, although the work must be in­serted and removed by an attendant.

Turret Lathe. — The characteristic feature of a turret lathe is the turret which is mounted upon a carriage and contains the tools "which are successively brought into the working position by index­ing or rotating the turret. Many turret lathes also have systems of stops or gauges for controlling the travel of the turret carriage and cross-slide, in order to regulate the depth of a bored hole, the length of a cylindrical part or its diameter.

Automatic Screw Machine. — The original field of the automatic screw machine was the making of screws. This field was quickly enlarged to include the making of all kinds of small nuts, washers, pins, collars, etc., and, at the present time, machines of this class are capable of a great variety of operations. Characteristic features -of screw machines in general are means for automatically locating successive tools in the correct working position, the automatic chang­ing of feeds and speeds and the presenting of new stock to the fools for a similar series of operations. These various movements, which are entirely automatic, are obtained principally from cams which are rotated at predetermined speeds. There are two general classes of screw machines: a single work-spindle and several work-spindles — usually four, five or six spindles.

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