Turret of turret lathe.
Side view. Top view.
The turret lathe, equally ingenious, has a turret or capstan, which carries let us say eight different tools, one on each of its eight faces. In its turn each tool operates on the work in its forward traverse; it then retires while the turret automatically moves through one-eighth of a circle, when the next tool emerges for its task, and so on.[7]
[7] The turret principle is embodied in drills and a variety of other machines. It was adopted in remarkable fashion by John Ericsson in his Monitor, launched in 1862 for service in the Civil War. Because this vessel had to navigate shallow streams, its draft was limited to eleven feet. As it was thus impossible to carry the burden of armor necessary to protect a high-sided vessel, he was obliged to design a sunken hull. Guns and gunner were protected within a covered cylindrical turret which as it turned on its vertical axis, delivered an all-round fire while the Monitor stood still. Ericsson’s original turret, and its later modifications in the leading navies of the world, are described in the Life of John Ericsson, by William Conant Church, New York, Scribner, 1890.
Ericsson’s Monitor.
Lathes have given rise to planers, now built of great strength and in highly complicated designs. In a lathe the object turns upon centers against a tool; a planer carries its tool in a revolving cylinder, the work being fed in a straight line. A shaper, with much the same essential construction, moves along its work, the wood or metal operated on remaining stationary. With a planer or a shaper the size and uniformity of the work depend upon the skill of the operator. The planer has led to the invention of a machine which dispenses with this skill. Bramah, in 1811, employed a revolving cutter to plane iron, adapting to metal the familiar mechanism for planing wood. This was the beginning of the milling machine, now so remarkably developed and improved. A skilled mechanic sets the machine and the chucks which hold the work; an unskilled hand can continue the operations, his products being uniformly of the dimensions and forms desired. Intricate shapes are easily executed, quite impracticable on any other machine. At first the revolving mechanism and its cutters were a single piece of metal; to-day cutters of costly quality are inserted in cheap metal; these inserted cutters when worn out are easily replaced.
Iron planer; a, b, c, d, fixed cutting tools; M, moving bed.
Niles-Bement-Pond Co., New York.
