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.
Pulley lathes, as they are commonly termed, might more appropriately be called pulley-turning machines, or even pulley-making machines, since some of them make the pulley complete, with the exception of splining and drilling and tapping for the set-screws. In some of these machines the boring is going on and the reaming is also done while the turning is taking place. In other forms, one machine does the boring and reaming, which may be done at quite high relative speed, while the turning must be comparatively slower and is done in another machine. Thus one machine for boring and reaming may furnish work enough for several turning machines.
In the pulley-turning lathes there must be a strong driving mechanism since comparatively large diameters are turned, although even the roughing cut is light when compared with that frequently taken by other lathes. Two and sometimes more tools are used, being located both at the front and back of the bed, (those at the back being bottom side up). In some machines the tools commence the operation in the center of the face of the pulley, and each tool or pair of tools (one roughing and one finishing), are fed away from the center, and with the slide upon which the tool block travels set in a slightly inclined position with reference to the axis of the lathe so as to produce the properly "crowned face" of the pulley. With four tools thus arranged, the pulley is completely turned during the time necessary for a tool to travel across one half of the face of the pulley plus the distance apart of the roughing and the finishing tool, say from an inch to an inch and a half.
When the pulley-turning lathe is arranged for turning cone pulleys it is customary to have as many tools as there are steps to the cone pulley, each held in a separate tool post fixed in a single tool block having a lateral power feed and a transverse adjustment for setting to the proper diameter. The tool posts set in T-slots and the tools are set with relation to each other so as to turn the proper relative diameters of the several steps. The tool block and the slide upon which it runs is adjustable to the right inclination or "taper" to properly crown all the steps of the cone at once, and when the tools have passed over one half the face of the steps, this block and slide may be shifted and properly adjusted to turn the other half of each step. In this form of pulley turning it is usual to make two cuts, a roughing and a finishing cut, and when turning up to the face of the different steps to draw back the entire number of tools by means of the transverse slide which may be fed back by hand for that purpose.
Pulley-turning and boring lathes or machines are built very broad as compared with an engine lathe and with very short beds, as the width of a pulley face, or the combined faces of the several steps of a cone pulley, is the extent of their lateral feed in any case.
The boring and reaming mechanism should have a power feed so as not to require the constant attendance of the operator, who may easily run one boring and reaming machine and two surface turning machines.
Shafting lathes or shaft-turning lathes may be arranged from any good engine lathe provided the bed is long enough for the purpose, by adding to it a three-tool shafting rest and a shaft straightener. Still a lathe that is especially designed as a shaft-turning lathe will be better adapted for the purpose and will turn out more good shafting with the same expenditure of capital and labor than the engine lathe arranged with attachments for the purpose. In the properly designed shaft-turning lathe there is a heavy shaft running the length of the lathe bed and arranged to communicate power to a face gear and driver journaled on the front end of the tail-stock, by means of which the shaft to be turned may be driven from this end as well as from the head-stock end. This is very useful in turning long shafts in which the torsional strain would be great, as the power may be applied at the tail-stock to turn one half of the shaft and then applied direct from the head-stock, or it may be applied at both ends continuously and simultaneously.
There should be a force pump to keep the cutting-tools constantly supplied with a stream of whatever lubricant is being used. This pump may be driven from the shaft above mentioned, which is located at the center of the bed and below the bridge of the carriage. The three-tool rest carries its own center rest, but it is customary to support the shaft being turned by easily removable rests used between the carriage and the head-stock or tail-stock, as the operator finds necessary. These are generally composed of two wooden blocks resting on the V's of the lathe and somewhat lower than the lathe centers. The upper block has a V-shaped groove for the shaft to rest in and is raised up and held in place by a wooden wedge inserted just far enough to give proper support to the shaft so as not to permit it to sag during the process of turning. There are three turning tools usually employed. The first is a roughing tool; the second cuts the shaft very closely to size, while the third takes an extremely light cut, completing the work, so that by running once over the shaft from end to end it is completely finished. Two tools are placed at the left of the center rest fixed to the tool block, and one, the final finishing tool, at the right. As these three tools and the center rest occupy considerable length upon the shaft the lathe is provided with extra long centers so as to reach the work. The center rest is provided with split collars bored to the size that the second tool leaves the shaft.
The turret lathe, shown in Fig. 24, now so well and favorably known, is a comparatively recent invention and doubtless originated in the use of a multiple tail-stock which was formerly used on small work where more than one tool was desirable. Our English friends recognize its value and usefulness, and one author speaks of it as "the common capstan tool-rest." In this country much has been done to develop and bring into popular form the turret lathe by such builders as Jones & Lamson, Warner & Swasey, Potter & Johnson, Bullard and others.