This section is from the book "Lathe Design, Construction And Operation, With Practical Examples Of The Lathe Work", by Oscar E. Perrigo. Also available from Amazon: Lathe Design: Construction And Operation.
Hand lathes are supposed to be for the usual operations of hand tool turning, filing and light metal turning by means of a detachable slide-rest. They may have legs of sufficient height to support them from the floor as in Fig. 16, or with very short legs, making them convenient for setting upon the usual machinists' bench as in Fig. 17. Otherwise their design and construction is the same.
Fig. 16. - A Hand Lathe.
Polishing lathes are, as their name implies, mostly used for polishing cylindrical work, although a hand-rest or a slide-rest is sometimes used upon them.
Pattern lathes, as shown in Fig. 18, are usually so called when used by wood pattern-makers and while usually used with hand tools, as chisels and gouges with the support of a hand-rest, at the present time a majority of them are provided with a slide-rest.
Those of larger swing have the rear end of the main spindle threaded for attaching a face-plate upon which is fixed large face-plate work of too great a diameter to be turned on the ordinary face-plate, as this supplemental face-plate overhangs the end of the bed and consequently the diameter of the work that can be turned is only limited by the height of the main spindle above the floor. In this class of work a hand-rest is supported by a tripod stand that may be moved to any desired position on the floor and is heavy enough to stand steadily wherever it may be placed.
Fig. 17. -A Bench Lathe.
Spinning lathes are used for forming a great variety of shapes from discs of quite thin metal, usually brass, with various shaped tools held either by hand or in the tool post of a slide-rest. These tools form the metal in a manner similar to the action of a burnisher instead of cutting it, usually over a former, by which the same shape is produced in all the pieces. Such work is not usually of large diameter, therefore a spinning lathe is generally of small and medium swing and is of substantially the same construction as the ordinary hand lathe, except when built for large or special work.
Chucking lathes, shown in Fig. 19, are used to a great extent for boring and reaming circular castings, as pulleys, gears, hand-wheels, balance-wheels, sleeves, bushings, flanges, and all similar work that require only the formation of the hole, although some of these machines are provided with a cross-slide and tool-post by means of which the hubs or bosses of the work may be faced. Many of them are now provided with a turret, by means of which several tools may be carried so that not only boring and reaming, but recessing, facing, etc., may also be done without removing the work from the chuck. These lathes usually have a very large driving-cone with a broad belt surface, or they are constructed with back gears similar to those in an engine lathe. It was from this form of lathe that the elaborate lathes built by Jones & Lam-son and others of similar design and construction originated.
Fig. 18. - A Pattern Lathe.
Fig. 19. - A Chucking or Turret Head Lathe.
In the second class we have what used to be called the "plain engine lathe," that is, one not provided with any thread-cutting mechanism. Formerly the smaller sizes of these lathes did not usually have the power cross-feed, although at the present time there are very few of them built by any of the manufacturers, unless by a special order, practically all the modern engine lathes having the thread-cutting mechanism, and frequently it is made an elaborate and expensive feature and covers a wide range of work. When these lathes were built to a considerable extent the feeding mechanism was nearly always driven by a belt, gears being very seldom used for this purpose. No sub-division has been here given for foot-power lathes, as any of those so far described can and have been operated by foot-power when not too large to be thus driven.
The Fox brass lathe, Fig. 20, is built upon similar lines as the engine lathe without a carriage or apron, but in place of it there is a swinging tool post slide whose rear end is journaled upon a lead screw which gives a longitudinal feed when the slide is brought over to the front by means of a handle for that purpose. With this driver, straight turning, facing, and thread cutting is quickly and conveniently done. There is also a hand-rest and sometimes a cutting-slide or cross-slide. The tail spindle has a long run and is sometimes worked with a lever, particularly when chucking work is to be done. Occasionally the tail-stock is replaced by a turret carrying a variety of tools such as are convenient for the brass finisher. These lathes are usually made without back gears. They are run at very high speeds and in the hands of an expert brass finisher do the work very rapidly, both as to turning and boring or inside finishing, while they cut threads very rapidly by means of "chasers."
Fig. 20. - A "Fox" Brass Finishing Lathe.
Forge lathes are a very heavy design of the plain engine lathe, without thread-cutting mechanism (although some manufacturers add this feature so as to make the lathes available as a complete engine lathe for much work that cannot be classed as forge work). The purpose of these lathes is to rough down large forgings, the users claiming that it is more economical to thus bring the work to the "forging sizes" than to do so by the process of hammering, and that all the chips thus removed may be worked into other forgings by which this waste is economically recovered. It is therefore their practice to forge the work (cylindrical work, of course) to dimensions much over the forge sizes, and by the use of the heavy forge lathe to finish them to customers "rough turned" to within reasonable limits of "finish sizes."