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 top slide is square gibbed and adjusted by a taper gib. The turret base is securely clamped in any position on the bed by two eccentric clamps operated by a wrench from the front of the turret.
The power feed is driven by a belt upon the four-step feed cones. It is positive in its action as a belt feed can be, and is engaged by a lever at the front of the turret and can be tripped to a line in any position by an adjustable stop.
The lathe shown is of 16-inch swing and has a circular turret 8 1/2 inches in diameter. It is drilled with six holes 1 1/4 inches in diameter. The automatic feed is 9 inches. It has a deep and strong bed and is in its design a very substantial machine.
As an example of the simplest form of a turret lathe with a hand turret mounted upon the carriage, the one shown in Fig. 306 is given. It is an 18-inch swing engine lathe built by the Springfield Machine Tool Company, and in this particular case a special carriage is shown, although it is very little different from the regular carriage upon which the turret may be as readily mounted.
In this case no cutting-off slide is provided, although one may be readily attached by fitting it to the V's and gibbing it to the bed in the same manner as the carriage is held to the bed.
Some of the special features and dimensions of this turret lathe are as follows, the information for the same being derived direct from the manufacturers.
This lathe is a modification of the standard 18-inch engine lathe, to serve the purpose of a heavy turret lathe, a type which is becoming deservedly popular with the manufacturers of machinery. With the exception of the turret on the carriage and the turret slide, the regular design of the engine lathe has been maintained.
The carriage is very heavy, gibbed to the outside of the bed, both front and back, and is fitted with a turret slide of unusual proportions - 10 inches in width and 16 inches in length, upon which the turret proper revolves.
The turret is hexagonal in form and 10 1/4 inches in width across the flats. The holes in the same may be as large as 2 inches in diameter, and the construction is such that a bar may be passed entirely through the turret. The advantages of this arrangement are too numerous and well understood to require any further explanation. The index pin and clamping lever are on the right side of the turret, and, although entirely out of the way, very convenient for manipulation.
The lathe is provided with power cross feed, as well as longitudinal feed and screw-cutting apparatus, and may be equipped with taper attachment if desired, and hence can perform on chuck or face plate work all the functions usually done with the regular engine lathe, with the advantage of greatly increased production within the same period of time. As a further convenience a taper attachment is added.
This taper attachment is designed with a view to strength and stability, and is attached to the rear of the carriage. It will turn tapers up to 4 inches to the foot.
Such a lathe is an exceedingly useful machine on a great variety of jobs continually occurring in the machine shop, particularly those of which there is a small quantity only to be made. Many of these jobs may have a portion of the work advantageously done on this lathe, and the balance on an engine lathe, both working in conjunction with more efficiency than either would alone.
In Fig. 307 is shown an example of what has been spoken of as a "monitor" lathe or turret head chucking lathe, although it is used for many kinds of work beside chucking single pieces. It is of 10-inch swing and built by the Pratt & Whitney Company.
These machines are used for drilling, boring, and reaming holes at a much faster rate and with more uniformity than similar work can be done on lathes formerly used for the purpose. They are also largely used to finish parts of machinery, cast or forged pieces of irregular outline and circular cross section, when fitted with the necessary tools.
Fig. 307. - 10-inch Monitor Lathe, built by the Pratt & Whitney Company.
They have the same construction as the revolving head screw machines above the bed, but are not usually furnished with the wire feed apparatus for feeding wire or rods through the chuck automatically, or provided with an oil tank, dripping device, etc., as the work usually done upon them does not require the use of oil in cutting. When oil is required these accessories may be readily attached.
The heads have provision for vertical and horizontal adjustment of the spindle in case its alignment with the turret holes is lost by wear. The spindles are made of hard, crucible steel, and are provided with cylindrical boxes lined with genuine babbitt metal.
The larger sizes of these machines are built with back gears, which render them capable of doing much heavier work than the machine shown in the engraving.
With this machine, with its quick acting and convenient hand lever for operating the turret, a very large amount of work can be turned out in a day; in fact, considering the cost of the machine, it is, for all work within its capacity, frequently more efficient than the larger sizes and more elaborate designs of this machine and others of the same general type.
The lever by which the turret slide is operated also automatically effects the revolution of the turret at the end of the return stroke and the beginning of the next forward movement.
There is a cutting-off slide carrying two tool-posts, so that a front and back tool may be used. One of these may be a cutting-off tool and the other a forming tool, if such a tool is needed. Thus it is adapted to turning to size, or several sizes; threading with a die in one of the tool-holding holes in the turret; drilling, reaming, etc., by the turret; and forming and cutting off by the cut-off slide, making it exceedingly useful considering its simplicity and economy.