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.
The turret is very heavy and well supported by the turret slide, upon which it is pivoted, and a long base slide or saddle. It is run forward and back by a capstan or pilot wheel with long levers giving ample hand power.
The turret can be connected with the carriage so as to be used for thread cutting and for tapping, as it thus connects positively with the lead screw by way of the apron. This feature is valuable in many respects.
In addition to the above convenience it has its own automatic feed, which has an unusually long run. As the turret has six large flat faces, each tapped with four holes in addition to the central hole for holding tools, it is well adapted for carrying large box tools, facing tools, or farming tools for special work.
The turret has the usual stops for regulating the length of the cuts, and a heavy binding nut lever for holding it firmly in any desired position.
It is altogether an exceedingly useful machine, combining many practical features, great weight, strength and rigidity, and consequently capable of performing very heavy work.
The turret-forming lathe is a machine that is very useful on a variety of work in which complicated outlines occur in a piece of circular cross section, and in which a large number of pieces of exactly the same design and contour are required. In handling brass work of this variety, what is known as the forming slide, vertical forming rest, etc., is found very useful, doing the work upon soft metals that the very heavy rest with its horizontal forming tools do for the harder metals, as iron and steel.
Fig. 304. -15-inch Forming Turret Lathe with Automatic Chuck, built by the Dreses Machine Tool Company.
In Fig. 304 is shown a 15-inch swing brass forming lathe, with automatic chuck. It is built by the Dreses Machine Tool Company.
The distinguishing feature of the machine is the forming slide, which consists of a base securely clamped to the bed and supporting a horizontal slide fitted in a dovetail and moved by a feed or adjusting screw. Upon the top of this slide is secured an upright having formed upon it a dovetail, and being adapted to swivel within a small arc. Upon the dovetail on this upright is fitted another slide which is moved by means of a rack, pinion, and lever. This latter carries the forming tool-holder, which is also capable of being tilted slightly and properly clamped when it is adjusted to the right position.
In front of the slide to which the upright is attached is placed an auxiliary small slide, provided with a tool-post and operated by the handle shown at the left. This slide is for use in cutting-off and for other final operations.
For the purpose of adjusting the forming tool to the chucked casting which is to be machined, the entire mechanism can be moved longitudinally on the bed by means of the rack and pinion.
A tightening clamp is provided by which the forming rest may be clamped or released instantly.
An automatic chuck is provided in which work may be gripped and released without stopping the machine. This is very convenient when bar stock is used.
While the machine, as shown, is without back gears, the manufacturers build them with this additional means of increasing the power when such is required.
The countershaft is of the double friction type, whereby six-spindle speeds are obtained.
The plan of adding the forming slide feature to the turret lathe is of much interest in manufacture, since it increases very much the range of the work for which the machine may be used, and with this forming slide so designed as to make it compound in its action, and including also the cutting-off tool-post, its usefulness is still further increased, making the machine as a whole a valuable one on all light machine operations for any work within its range and capacity.
One of the plainest types of turret lathes is built by the R. K. Le Blond Machine Tool Company and is shown in Fig. 305. Its plainness and simplicity are its strongest points. While its initial cost is reduced to a minimum, its capacity for handling a variety of different kinds of work is not correspondingly lessened, as it is well adapted to the lighter kinds of steel work, to cast iron of considerable dimensions, and to work of brass and other softer metals. Notwithstanding the fact that this limits its range of work somewhat, it is a machine of much practical usefulness as a great variety of light manufacturing comes well within its range, and it can be done as well and as rapidly as on a much more complicated and expensive machine.
The head-stock is long and heavy, supporting boxes for the spindle journals of ample dimensions. The spindle is hollow and of large size so that bar stock may be worked up. The end thrust is taken by ball bearings which minimize friction. The driving-cone has four steps and is adapted for an extra wide belt. The countershaft is of the double friction type, thus giving eight speeds.
Fig. 305. - 16-inch Plain Turret Lathe, built by the R. K. Le Blond Machine Tool Company.
The turret is very simple, having as few parts as possible in their construction. The turret proper revolves automatically, and when the top slide is flush with the bottom it can be revolved freely by hand and any desired tool brought quickly into position for work. The indexing ring is of large diameter and made of tool steel, hardened and ground, as is also the locking plunger, which automatically adjusts itself for wear. The wear between the turret and the stem upon which it is pivoted is taken up by an adjustable taper bushing.