Fig. 87. A GRINDER AND POLISHER
A plain lathe, see Fig. 88, is good for turning, drilling and facing metal parts and for many other operations. It consists of a bed supported on a frame which carries the driving pulleys; the latter in turn is belted to a cone pulley which is keyed to the mandrel and this runs in bearings in the headstock. The inner end of the mandrel projects beyond the bearing and this is threaded so that a chuck, that is a device with adjustable jaws for holding the work, can be screwed on it.
Besides the headstock which carries the rotating mandrel, and which is fixed on the left hand side of the bed, there is a tailstock with an adjustable mandrel which slides on the right hand end of the bed, and between the headstock and the tailstock there is an adjustable hand rest.
Fig. 88. A PLAIN LATHE FOR TURNING METAL WITH HAND TOOLS
An engine lathe, as shown in Fig. 89, besides doing all an ordinary lathe can do can be used for accurately turning up cylinders, disks, etc., turning out cylinders and cutting screws of any size or pitch, within certain limits, and it does all these things with rapidity and precision.
A lathe of this kind has a guide-screw, a set of change wheels, that is a number of interchangeable gears, and a back-gear, and by means of these gears the guide-screw is revolved in any ratio to the speed of the gears which may be desired. For turning or cutting a slide-rest is used, that is an attachment sliding between the headstock and the tailstock, for holding the tools.
Fig. 89. AN ENGINE LATHE FOR TURNING METALS WITH TOOLS IN A SLIDE REST
The slide-rest is made with two adjustable slides so that the tool can be held in any position. The slide-rest can be moved freely by hand or by means of the guide-screw which carries it along the bed at any desired speed.