The cutters or slotting-tools for use in slotting-machines, are represented in Plate 61. In this plate, Fig. 782 represents a groover having a short thin end; and is suitable for cutting key-grooves which are but short, or of but small width and depth. The tool consists of but one piece, consequently, the cutting end is produced by reducing a portion of the thick part termed the stalk, (see page 225). A slotting-tool with such a small end is also used for commencing or partly forming slots and grooves, that are to be also partly formed with other slotting-tools.

Fig. 783 represents a slotted tool, in which is keyed a separate cutter. Such a tool is used for the convenience of making one stalk serve for a number of cutters whose shapes and sizes differ from each other; also for avoiding the reduction of the stalk, whenever a new cutter is to be made. The movable cutters are quickly made of steel of proper thickness and width, and the cutting edges are easily ground to any desired shape and angle, to suit their special work. The stalk shown by Fig. 784, is also used for holding movable cutters, but has its entire slot situated above the bottom, this arrangement being sufficient for holding very short cutters.

A tool which is employed to form comparatively long and narrow slots and grooves, is indicated by Fig. 785. When it is requisite to employ a slender cutting end of great length, the end is thinned behind its cutting edge, and spread out, as seen in the Figure, to obtain strength for preventing bending and breakage through the strain imposed while cutting the metal.

If it is required to form a very long groove, which is but shallow, a tool having a cutting-end projecting but a very short distance from the stock's side is suitable, because the stalk may then pass along very near the object to be cut, but without touching it. But for making a deep groove, or one which is to extend deep into the metal it is necessary to provide a long cutting end, and to keep the entire stalk-portion of the tool above the work. Consequently, a groove which is to be comparatively shallow, is properly cut with a movable cutter, similar to that shown in Fig. 783 or 786; and another groove, which probably is to be no longer than the shallow one, but is to extend much deeper into the metal, will be properly formed with a tool having a long end, resembling that denoted in Fig. 785.

Slotted-stock tools, which are necessary for shaping outsides of bosses, outsides of other articles having convex surfaces, and also articles having concave surfaces, are represented by Figs. 787 and 788. In these Figures, the cutters consist of short vee-point tools, similar in shape to slide-rest tools, but having short stalks. A one-point cutter of this class is keyed in the slot, so that the cutting point shall be at any exact distance from the stalk that is necessary. For shaping outsides of lever-bosses by such a tool, the point is in all cases situated very near the stalk, to obtain great rigidity while cutting, and because the point is, for such shaping, never required to extend deeply into the metal, as requisite while forming a groove. The cutter which is shown in Fig. 787, is one which is suited for iron and steel; and the one seen in Fig 788, being straight, is suitable for brass and gun-metal.

Feather-tools are those which are indicated by Figs. 789 and 790. A tool of this class consists of a stock and a feather-portion, this portion being solid with the stock, and constituting the cutting part of the implement. Fig. 789 shows a half-feather tool, and has but one cutting portion; whereas that shown by Fig. 790 has a complete feather-part, and cuts at either or both sides of the tool, if required. Such tools are used for making key-grooves into lever-bosses and wheel-bosses, a tool which has a complete feather being employed to form two grooves into opposite sides of a boss at one fixing of the object. Two grooves of this character can also be easily made with a slotted tool and a keyed cutter, such as that shown by Fig. 795, and for a great quantity of work such tools are preferable to feather-tools.

Although feather-tools of large sizes are used, there is no advantage resulting from their employment, except that they sometimes avoid the necessity of making a slotted stock and its cutter. Feather-tools are troublesome to forge if large, because of the necessity for upsetting and fullering the sides, to produce the feather-portions; their use should therefore be avoided, except for small grooves which may be only about a quarter of an inch in width or depth. For a small groove, a feather can be quicker made by the fullering referred to, than by drilling and filing a slot and preparing a distinct cutter.

The slotting-tool shown by Fig. 791 is a mortiser. These are a very useful class of tools, both because they can be easily made and mended, and because they suit a great variety of work. The cutting end of such a tool is easily formed by thinning a part of the thick stalk-portion until a stem of the proper length and thickness is produced. This end, after being made small enough, is bent forwards, in order that the cutting-edge may at any time during cutting, be in contact with the metal without allowing the stalk to touch. This arrangement is termed clearing the stalk, and will permit a key-way or other groove to be made, the length of which is greater than the length of the tool's thin end or stem, because while cutting such a groove, a portion of the stalk is allowed to pass along near the object without touching it. The distance into the metal or depth, to which a mortiser's end will extend while cutting, depends on the distance which the tool's cutting edge is situated beyond the stalk; consequently, the greater the extent to which the tool is bent, the greater the depth to which the groove may be cut. There is, of course, a limit to which the bending forwards of the stem may be carried, because the tool is weakened thereby, and therefore made liable to quiver and break. In general, mortisers are suited to work of all sizes, and for all grooves which are of comparative great width.

A short springy tool keyed in a stocker is denoted by Fig. 792. Springy tools in slotting-machines are employed to smoothly polish surfaces, as in planing-machines and shapers. The tool seen in the Figure (792) is one having a nearly straight cutting edge, and is useful to smooth the outsides of bosses after they are roughly shaped with vee-point tools. Other springy tools, having curved cutting-edges, may also be keyed in the same stocker, when necessary; curved tools being required to shape grooves with curved bottoms, and also to shape ridges and corners. Point-tools also may be keyed in, resembling those in Figs. 787 and 788. It will be noticed that the slotted ends of the stocks seen in Figs. 787 and 788 are of no greater thickness than the upper portions; consequently, such stocks are suitable for holding comparative small cutters; whereas a stock with a broad boss, resembling that in Fig. 792, may be employed for holding comparative thick cutters made of square steel.

The point-tools represented by Figs. 793 and 794 are used for the same class of work as the tools denoted by Figs. 787 and 788. The difference in the two species of tools consists in the one having cutting ends which are solid with the stocks, and the other species having slotted ends for containing distinct cutters. Those which are slotted should be used for large work in general, and the solid ones for all small articles, such as those that require stocks only about an inch square. Square steel of about this size is easily reduced to produce the cutting ends suitable for small objects. Both these species of tools will perform similar work, which consists in shaping convex surfaces, such as the outsides of lever-bosses and objects of similar shape. These tools will also shape concave surfaces, which include those belonging to rims of wheels, curved junctions of arms, links, and bearer-brasses.

A tool which somewhat resembles a feather-tool is denoted by Fig. 795 ; but in this the cutter is a distinct piece of any length and thickness, which is keyed in the slot when required tor use. A tool of this class may be used in two ways, either by making it cut at one side of a hole, or at two opposite sides, as if it were a single piece like a feather-took Generally speaking, it may be said that this and all other slotted tools for holding distinct cutters, are more suitable for large work than small, because after the slots are formed at the first making of the implements, all future forging for repairs is performed upon the comparative small movable cutters, and is therefore much easier than forging the thick stalk-portions. Another advantage belonging to a slotted tool consists in its allowing the cutters to be detached when they are to be ground, without the need of removing the stock from the tool-clamps.