The essential elements of a lathe. The bed. The head-stock. The tail-stock. The carriage. The apron. The turning and supporting rests. The countershaft Taper attachments. Change-gears. Classification applied to materials, labor accounts, and the handling of parts in the manufacture of lathes. The four general classes of lathes. The eighteen sub-divisions of these classes. The first class: hand lathes, polishing lathes, pattern lathes, spinning lathes and chucking lathes. The second class: engine lathes without thread-cutting mechanism, Fox brass lathes, forge lathes, and roughing lathes. The third class: complete engine lathes with thread-cutting mechanism, precision lathes, rapid reduction lathes, and gap lathes. The fourth class: forming lathes, pulley lathes, shafting lathes, turret lathes and multiple spindle lathes. Rapid change gear devices. Bancroft and Sellers device. The Norton device. Lathe bed supports. The precision lathe. The rapid production lathe. The gap lathe. Special lathes. Forming lathes. Pulley lathes. Shafting lathes. Turret lathes. Screw machines. Multiple spindle lathes. Variety of special lathes.

In considering what are the essential elements of a lathe they may be briefly stated, if we assume that in a simple lathe the work is to be what was originally intended, that is, held on centers, and may be stated in these terms, viz. The essential elements of a simple metal turning lathe are: suitable means for supporting and holding the work upon centers; proper mechanism for rotating the work; and a cutting-tool properly held and supported upon a traveling device actuated by suitable mechanism.

The first of these essentials comprise the bed, head-stock, and tail-stock, with their proper parts and appendages, so far as the fixed parts and centers are concerned, and including legs or other supports for the bed. The second essential comprises the driving mechanism, consisting of the driving-cone, back gearing, etc., and the third essential consisting of the carriage, tool block, and cutting-tool, with the necessary gearing for moving it, and the connecting parts for transmitting power for that purpose from the main spindle of the lathe.

This classification of the essential elements of the lathe naturally suggests certain groups of related parts which compose a complete lathe, and correspond with the experience and practice of the author in the designing and construction of the various types of lathes. They are as follows:

1. Bed and appendages, including the legs or cabinets, lead-screw and its boxes, the feed-rod, its boxes and supports, carriage rack, tail-stock, moving rack (when the lathe is large enough to require one), stud-plate and studs, and such necessary bolts and screws as are needed to fasten these parts.

2. Head-stock and appendages, including such feed-gears as are necessary to connect with the feed-rod in case of a geared feed. Also the holding-down bolts and binders (if used), for fastening the head-stock to the bed, and the large and small face-plates. (Where a quick change gear device is used and is not an integral part of the bed or head it forms a separate class.)

3. Tail-stock and appendages, such as holding-down bolts, binders, and, when the lathe is large enough to require it, the mover bracket, gears, shafts and crank; and if the tail-spindle is handled by a hand-wheel in front, the brackets, shafts, spur and bevel gears, etc.

4. Carriage and appendages, including gibs and a solid tool block if one is used, but not a compound rest where" these are furnished at the order of the purchaser. If the lathes are habitually built with compound rests they may be classed with the carriage.

5. Apron and appendages, including the apron in its complete assembled form ready to attach to the carriage, together with the screws for making such attachment.

6. Rests, including the compound rest (when not classed with the carriage, the full swing, pulley or wing rest (as it is variously named), center rest, back rest, (when one is furnished), together with bolts, binders, and similar means of attachment.

7. Countershaft and its appendages, including the hangers, boxes, shipper rod, etc., and any similar parts for tight and loose pulleys or friction pulleys as may be necessary to make it complete and ready to put up.

Taper attachments, special tool holders, or tool-rests, and all similar parts are deemed extras and not included in regular lists.

Change-gears are sometimes listed as a part of the bed and appendages. When these are a part of a special quick change device they are made a separate class. This is understood to be when the change gear device is detachable. When made a part of the head-stock or the bed such parts as are attached to the one or the other of these main parts will be listed with it and become a portion of its appendages.

This classification is carried into all lists of materials of whatever kind and into all accounts of labor in the designing, constructing, and handling of these parts, whether in groups or as single pieces, during their progress through the various departments of the shop.

The classification of these lathes as entire and complete machines, and according to their Various types of design and construction and the uses to which they are to be put, will be next considered, and in so doing it seems appropriate to commence with the more simple forms, and to proceed with such types as are commonly recognized and in use at the present time, dividing them into four general classes and these into such sub-divisions as their construction and uses seem to demand By this method of classification we shall have:

First Speed Lathes.

Hand Lathes, for floor or bench.

Polishing Lathes.

Pattern Lathes.

Spinning Lathes.

Chucking Lathes, with or without a turret.

Second Metal Turning Lathes.

' Engine Lathes, without thread-cutting mechanism.

Fox Brass Lathes.

Forge Lathes.

Roughing Lathes.

Third Engine Lathes.

Complete Engine Lathes with thread-cutting mechanism.

Precision Lathes.

Rapid-Reduction Lathes.

Gap Lathes.

Fourth Special Lathes.

Forming Lathes.

Pulley Lathes.

Shafting Lathes.

Multiple Spindle Lathes.

Turret Lathes.

In the first class we understand by speed lathes a lathe without back gears and without the carriage and apron of an engine lathe, although as chucking lathes they may be provided with back gears, as they are frequently used for boring quite large holes, and are therefore made much larger and heavier than those of the other sub-divisions of this class.