The outer curved surfaces of lever-bosses are shaped with shaping-machines, planing-machines, and slotting-machines. Of these machines, shapers are suited for all small levers in general, if they are not more than nine or ten inches in length. Shapers are also very effective for shaping lever-bosses which are situated in the mid-portions of levers, named fulcrum-bosses. Levers of this sort are also conveniently shaped along their entire lengths, when necessary, by the same shaper used to shape the bosses. Planing-machines are also available for this same shaping of mid-portions of levers, and through these machines being usually larger than shapers, the reducing of a large lever on a planing-machine is easier done than with a shaping-machine, the cutting tool of a planer being more capable of effecting thick cuts.

In order to shape the outside of a boss which is situated at one end of a lever, by means of a shaper, the rotating conical pivots at the front of the machine are employed for holding the boss, the two conical ends being in the hole of the boss while it is screwed tight between. To cause the boss to rotate in a path which is concentric with the cylindrical hole, the boss is properly bored, and its faces turned to make them right-angular to the hole's length. It is also usual to take off a portion of the metal at the outer edge of each boss-face; at which part the boss is reduced to the finished diameter intended for the entire boss when finished. If the boss-ends are of considerable length, causing the faces to extend a quarter of an inch or more, from the broad sides of the lever, it is also usual to lathe-turn the entire lengths of these boss-ends. By turning these two parts to the same diameter, and making this to be the finished diameter, the superfluous quantity of metal to be cut off with the shaper is plainly shown, and the boss is made ready for immediate fixing to the machine-pivots for being reduced to the proper dimensions, no lining being necessary. When the boss is without such projecting ends, it is requisite to scribe two circles, one on each boss-face, both circles being of the same diameter, that they may show the amount of metal to be removed, as if the boss were partly lathe-turned. For this scribing, the primary centre line along the lever's broad side must be used, in order to cause the boss, when shaped, to be in a straight line with the intermediate portion. It may be here mentioned that whatever straight gauge-lines may exist along the lever's length, which are now to be used during shaping, are the lines that were placed previous to lathe-turning or boring, and were employed to adjust the lever for the purpose; and the same primary lines should now be used, to make the outside of the boss parallel with the hole.

The boss being properly prepared, it is fixed between the pivots so that its length is nearly horizontal, in order that the upper half of the boss may be shaped at one fixing; after which, the boss is put upside down and the other half shaped. In some cases, the entire boss can be shaped at one fixing, when it happens that the lever is not too long to permit the necessary extent of rotary movement.

Adjusting the tool for cutting after the lever is fastened is effected with the vertical traverse screw of the slide-rest, an ordinary vee-point facer being used. The tool-point is so placed that it is exactly over the centre of the pivots and therefore over the centre of the hole in the boss, which situation is known by a gauge-line on the machine. The machine is next arranged to work with the to-and-fro motion of the tool, and the rotary motion of the pivots, all other movements being stopped except the small advancement downwards of the tool-point, for causing it to enter the metal a proper distance, and thereby taking off the required quantity. When the tool-point is put to the proper height the shaping proceeds until the half-rotation or three-quarters rotation of the object is effected, and therefore the entire boss reduced, one slice being cut off. The tool-point is then again advanced downwards a short distance and another slice is removed by another rotation as before. The reduction of the boss is thus continued by as many rotations of it as will suffice to attain to the finished diameter, which is shown by the circular gauge-lines on the faces or by the turned boss-ends which were before referred to.

It is now supposed that the boss is finished with the exception of the curved junctions of the boss with the other portion of the lever, and that it is required to shape this middle or straight portion. If this is to be done it may be next fixed so that its length is nearly parallel with the direction of the machine's horizontal traverse, the upper gauge-line to which the mid-part is to be reduced being adjusted exactly parallel with the traverse. The object is now in position for cutting off the superfluous metal at the upper narrow side of the lever and along its length. The curved junctions also can be shaped, both the junction of the boss already finished, and that of the boss to be shaped, if this shaping is necessary. The lever is next put upside-down, and the other narrow side of the mid-part is shaped and the junctions also. This leaves one of the bosses yet to be shaped, which is effected by removing the lever from the conical pivots and placing it end for end, placing the boss not shaped on the pivots in the same condition as the first one. The shaping now proceeds in the same manner as before by the rotation of the boss and the gradual advancement downwards of the tool.

To avoid unnecessary shifting when a comparative large lever is to be thus shaped, both its bosses and all its four curved junctions should be finished previous to beginning the reducing of the straight mid-part. This will avoid arranging the machine a second time for the rotary movement to shape the second boss.

A lever which is shaped by these methods is fastened in position during the reducing of the straight portion by one boss being fixed on the pivots, as when being rotated, and with the other boss bolted to a parallel ring or packing in contact with one boss-face. This mode of fastening suits small or short levers; but a long one should be entirely disconnected from the pivots when the straight part is to be shaped, at which time it can be properly held against an el-chuck; in this position the action of the cutting tool will not bend the lever, and thereby cause an unsteady cut.

When the outside of a boss is to shaped with a planing-machine, it is done by fixing the boss against an el-chuck, and gradually adjusting the tool-point by rotating the vertical traverse screw during the to-and-fro movement of the object in contact and being cut. This gradual raising and lowering of the tool while it travels across the boss is done by the hand of the operator, who watches the gauge-lines on the boss-face, and adjusts the tool accordingly. To avoid a tedious operation of this sort a special apparatus for a rotary motion must be supplied to the machine, but such a movement is not necessary now that shapers and slotters are accessible ; and when, through sudden breakage, or other emergency, a planing-machine must be used for reducing a large boss, the hand adjustment of the tool can be effected without much difficulty.

For the shaping of a lever having three bosses, a planing-machine is frequently more convenient than a shaper, especially if a large amount is to be cut off, requiring very thick cuts. When a great quantity is to be removed, the horizontal traverse will effect the reducing, a tool having a broad vee-point being used and much of the hand-working of the screw avoided.

The planing of the object to the finished size desired, is conducted with regard to gauge-lines in the same manner as if the lever were shaped on a shaping-machine ; the lever being in all cases adjusted so that the gauge-lines to which the metal is to be cut off, are placed parallel with the surface of the planing-table.