Single Verfical with Combined the sin gle-spindle drilling-machine, represented in Figure 1 (p1. 26), the working machine is combined with a motor, forming in this case a vertical drilling machine with an oscillating steam-engine. Such a combination offers many advantages. The working machine being entirely independent of other machines, the uniformity of its running is not affected by nor does it dis turb the others; power is used only while the machine is running, and port ability, applicable in the construction of large materials—bridges, ship hulls, etc.—is obtained by conducting the power (steam, water, or com pressed air) from its source to the machine. A bevel-pinion upon the engine crank-shaft drives a large bevel-wheel, whose shaft carries the drill-bit. The feed is by hand, the vertical shaft upon the large bevel wheel being hollow and internally threaded. This machine has its anal ogy in those mortising-machines for wood in which the mortise is made with straight sides, flat bottom, and semicircular ends by a rotating auger having a traverse at right angles to its axis, the ends being squared by a mortising-chisel after the auger-bit has clone its work. With the metal working cotter-drill, if it be desired to have square ends to the groove, they may be either chipped out with a band-tool or squared by a slotting tool. In the ordinary drill the work is held stationary, and the tool, whose axis is vertical, is given rotation, while its feed is only in the direction of its axis. In the cotter-drill the tool is given feed in the direction of its axis, and the work is also fed at right angles thereto.
Colter 9, 10, and r 1 (pi. 25) show an admi rable general application of drilling-machines, in which, besides the two motions previously referred to, there is added a third—namely, a recti linear translation of the material at right angles to the drill axis (fig. 9), or, with the material remaining stationary, the same motion is imparted to the drill, drill-spindle, and appurtenances. Suppose the drill has pen etrated the material to a certain depth and this forward-and-backward motion there takes place within certain limits, the drill being fed sidewise every time it is reversed; then, instead of a circular hole, the result will be a groove with semi-cylindrical ends. The ends of these drill-cut grooves can subsequently be readily made rectangular by means of a chisel. These machines form a transition from drilling- to milling-machines. The bits used for them are shown in Figures i to 5 (pl. 25). Figure r represents a double-pointed drill and Figure 2 a rose-bit. Figures 3 to 5 are reamers.
and the boring-machine proper the work is stationary and the tool rotates about an axis coincident with that of the piece to be bored. The tool has at the same time a lengthwise motion parallel with that of the work being bored; and if taper or other non cylind rieal boring is done, the tool has also an in-and-out motion at right angles to the axis of rotation. In boring- and turning-mills the work
rotates, the tools having practically the same motions as upon an ordi nary lathe, except that in the lathe the axis of rotation is always horizon tal and in the boring- and turning-mill it is generally vertical.
The boring- and turning-mill is now a necessary part of the outfit of any large machine-shop. The Niles type, shown in Figure 2 GM 26), is a leading example. There is a very heavy table, driven by spur-gearing and having a long massive spindle running in bearings adjustable for wear. For light work the table is carried only upon a steel step, but for heavy work the step is relieved and the table lowered upon an annular bearing under its outer edge. The driving-belt is at the side. The cross rail, which carries the tool-heads, is raised and lowered by power. The tool-bars, which are counterbalanced by weights, can work at any angle, can be operated from the end of the rail by hand, together or independ ently, and can also be worked at the saddles by a quick hand movement, while the feeds are automatic in every direction, and also variable in very great degree. The right-hand saddle has quick traversing movement by hand in addition to a slow hand movement and the feed. Besides boring and turning, this mill, by an attachment, can without clamping do pulley turning on a mandrel, slotting and key-seating, cylinder-boring, thread cutting in large valves, grooving in hoisting-apparatus, drums, etc.
tools for planing metals (t./. 25, figs. 6-8) are of larger dimensions than those for wood and have a greater cutting-angle, corresponding to the greater resistance of the material. They usually have a convex edge or an angular cutting-point, and consist either of a single piece of steel (fig. 3) or of a short piece set in an iron holder (figs. 6, 7). These tools are used only in machines applied to metal-planing.
Though nearly all the machines for working wood, and commonly called "planing" machines, are substitutes for the hand-plane, they are actually cutting-machines, since they work Nyith revolving tools. Metal-planing machines may be divided, according to the direction in which the sepa rate cuts are executed, into vertical and horizontal, and the latter may be divided into planing-machines with movable irons and those with station ary irons.
Horizontal of the planing work upon metal, as upon wood, is done in a horizontal direction. In small work the mate rial is held still and the tool is given a comparatively slow working-stroke and quick return, the feed being effected after the working-stroke is com pleted. Such machines are termed "shapers." For large work, by some strange inconsistency, the piece to be operated upon is given horizontal movement for the working-stroke while the tool is held still, the feed for the new cut being effected after the working stroke is made, and the return or idle stroke being comparatively rapid.