Metal-Cutting Machines. LatheThe most useful and versatile machine in the workshop is a turning machine (lathe). As the name shows it is used for turning different objects and parts. However, besides turning many other operations can be performed on a lathe. Such as drilling, reaming, tapping and by employing suitable adapters operations of milling and grinding may be carried out without difficulty. The lathe consists of the following basic parts: the bed, the headstock, the tailstock, the saddle (or carriage) with the tool-post and the driving and gear mechanism. The bed is a base for supporting and aligning the components of the machine. At the opposite ends of the bed there is a headstock and a tailstock. The headstock carries a pair of bearings in which the spindle rotates. The spindle holds the workpiece and rotates with it. The headstock also incorporates the driving and gear mechanism. The parts of this mechanism: are the feed shaft and the change gearbox. The feed shaft is designed for driving the tool-post, and the change gear box drives the spindle of the lathe at various speeds. Tapered centres in the nose of the spindle and of the tailstock hold the work firmly between them. The tool-post is driven along the saddle either forwards or backwards at a fixed and uniform speed. That is why the operator is capable of making accurate cuts and giving the work a good finish. There are many types of lathes but all of them operate on the same basic principle: the workpiece is revolved by power and a cutting tool is brought against it, removing metal in the form of chips. The other principle of operation is that used in milling, grinding and drilling machines. In these machines the tool is fixed and the work is moved to and fro against it in a horizontal plane.
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