Importance of the turret lathe. Its sphere of usefulness. Classification of turret lathes. Special turret lathes. The monitor lathes. The Jones & Lamson flat turret lathe. Its general design and construction. Its special features. Its tools. The Warner & Swasey 24-inch swing universal turret lathe. Ganeral description. Its capacity. Taper turning attachment. Its speeds. The Bullard Machine Tool Company's 26-inch swing complete turret lathe. Its massive form and its general design and construction. Lubrication of tools. The countershaft. The Pratt & Whitney 3 by 36 turret lathe. Its special features. Its general desing. Its capacity. Special chuck construction and operation. The Gisholt turret lathe. Its massive design and construction. Its large capacity. Its general and special features. The Pond rigid turret lathe. Its heavy and symmetrical design. Detailed description. Its operation. General dimensions.

While the regular engine lathe is in almost universal use wherever machine work is done, and while it is the one indispensable tool in every machine shop, the modifications of it in the various forms of a turret lathe are becoming second only in the importance and the range of its work. So great has been the advance in this respect during recent years that nearly all machine shops, even small jobbing shops, are not considered as possessing a passably modern equipment without one or more turret lathes.

Formerly it was not thought worth while to "set up" a job on a turret lathe unless there were fifty or more pieces of the same kind to be machined. It is now a common occurrence to use the turret lathe when only half a dozen pieces of a kind are to be made. The reasons for this are that formerly special tools had to be made for many of the jobs attempted, whereas now we have a great many regular tools furnished with the turret lathe that are of such form and construction as to be available for nearly all the ordinary turret lathe jobs, while the addition of an extra tool now and then for special work, or a special form, will adopt the turret lathe for a very large variety of work, which may thus be performed with a great degree of accuracy, with a very good finish and in a very economical manner.

Where large numbers of pieces of the same kind are to be made, it is usually the practice to make special tools whenever better work or a larger output can be thereby secured. This will be largely a matter of practical judgment of the man in charge of the work.

We may divide the turret lathe proper, and the engine lathes when used as turret lathes by the addition of a turret, into five classes, according to their design and methods of operation, namely:

First, the engine lathe serving as a turret lathe by mounting a hand-revolved turret upon its carriage, in place of the usual compound rest.

Second, the engine lathe serving as a turret lathe by mounting a hand-revolved turret upon the bed by means of a shoe or saddle which supports the turret slide.

Third, a turret lathe proper, built as such, with a turret pivoted to a slide supported by a shoe or saddle; the turret being revolved and fed by hand.

Fourth, a turret lathe similar to the last and sometimes called a "semi-automatic turret lathe," in which there is a power feed on the cut and the turret is revolved automatically at the end of the stroke.

Fifth, a complete automatic turret lathe with power feed on the cut, a quick power return, and the turret automatically revolved at the end of the stroke.

Those in the third, fourth, and fifth classes are usually provided with a cut-off slide carrying one tool in front and frequently an inverted tool at the back.

Various examples of these different classes will be illustrated and described in the following pages, giving the designs built by several of the prominent manufacturers of this type of machines.

There are, of course, special machines of this general type of lathes built for special purposes. There are modifications of the general class, into the details of which it is impossible to go in these pages, since it is the object to present distinct types or classes, rather than to expand this work to the dimensions of a cyclopedia on the subject of lathes.

There is one type that deserves special attention on account of its valuable service on small work, and that has been known in the shop for many years as a "monitor" lathe,from the fact, no doubt, of its resemblance to the turret of a monitor. The slide upon which the turret is pivoted is run forward and back by a lever which makes it very rapid in operation. It is usually built for small work only.

The Jones & Lamson flat turret lathe is now so well known that an extended description of it seems hardly necessary, and yet its importance in the manufacturing world of to-day, and its many points of real mechanical interest and importance, demand more than a passing notice.

A front view of one of these machines is given in Fig. 286, this particular machine being 3 x 36-inch size, that is, it will work up a 3-inch bar and the turret has a run of 36 inches on the bed.

As will be seen the bed is supported by strong and well designed legs in a pan nearly the full size of the machine. The head-stock and its gearing is covered by a protecting case which moves with it. One of the peculiar features of the machine being the sliding head which has a transverse movement for the purpose of increasing its effective working capacity. The turret is mounted upon a saddle fitted to broad V's upon which it has a long bearing, insuring accurate results.

The turret is a flat circular plate and is mounted on a low carriage containing controlling mechanism. The connections of the turret to the carriage, and the carriage to the lathe bed, are the most direct and rigid, affording absolute control of the cutting-tools. The turret is accurately surfaced to its seat on the carriage by scraping, and securely held down on that seat by an annular gib. In the same manner the carriage is fitted to the V's of the bed; the gibs passing under the outside edge of the bed. The breadth of this bridge across from V to V makes an unyielding mass to which the tools can be affixed.