To adjust a lever on a drilling-table for boring, it is necessary to put the planed side parallel with the table by means of parallel blocks, which are put beneath and in contact with the plane surface to keep it high enough above the table for the boring-tools to freely disengage from the metal. Both the shaft-hole and the crank pin-hole are formed on this machine, and a proper amount of metal is allowed to remain for the lathe-boring. Two fixings for each lever are therefore necessary on the drilling-machine, although it need not be very accurately adjusted because its boring will be completed with a lathe.

The modes of attaching levers to lathe-chucks, are represented by Figs. 1044, 1045, and 1046. The first fixing of a lever is denoted by Fig. 1044, in which a lever is seen in position for boring the shaft-boss, being situate on two parallel blocks shown by B and B. On the front or narrow side is seen a dotted line, which is scribed exactly parallel with the planed boss-faces. This can be easily marked with a scriber-block on a table if the lever can be easily moved thereto ; but a large one may be scribed while it remains fixed on the planing-table at the time of planing the boss-faces. The line can be marked also while the lever is on the lathe-chuck, the scriber-block being put against the chuck's face instead of upon a lining-table. The line is marked upon both sides, and is a species of gauge-line from which the lengths of the bosses can be shown, and is also useful to refer to during the adjustment of the lever to parallelism with the chuck. Supposing the distance between the two faces of a boss is required to be eleven inches, and the gauge-line to be situate five inches from the planed boss-face, and that this face is finished, it will be necessary to reduce the outer face of the boss until it is six inches from the line, which distance is shown by adjusting a compasses to six inches, and scribing a short arc upon the boss near the face being reduced.

The holdfast plates and bolts shown in the Figures are the principal ones required to hold the levers, and are attached at the first fixing to the chuck. In addition to these, three or four other plates and poppets are placed along the arm, as soon as the object is put nearly into its proper place on the chuck. The piece near the lower edge, is a balance-weight of lead or iron, denoted by W. This is bolted to the chuck opposite the lever, in order to balance it during rotation. These weights are of various sizes and thicknesses, so that several may be used together if needful, that the quantity of metal applied may be neither too little nor too great. To ascertain whether the lever is properly balanced, it is put with its length exactly horizontal, by rotating the chuck a short distance without the leather band; the power-gear and step-pulley, are also disconnected from the lathe-spindle; and if the lever will now remain horizontal while thus free to move in either direction, the weight of the balance-pieces is that which is required.

While finally adjusting a lever-boss on the chuck, a pointer or tool-scriber is used, which is bolted tight in the slide-rest. The lever is next slowly rotated and gradually shifted with the poppet-screws until the circular gauge line on the boss-face is seen to exactly coincide with the point during any portion of the lever's rotation. The object is now to be finally fastened by screwing tight the plates; and is in position for smoothly boring the hole parallel, and to the diameter required, which is done with the slide-rest tools. When the hole is finished the holdfast plate is removed from the boss-face, if such a plate were used, that the face may now be reduced until the boss is of proper length. The circular boss-end is also turned to the proper diameter; and a short portion of the lever-arm adjoining, is also turned, which forms a ridge, if it is intended to reduce the arm ; if not the projecting -boss-end is carefully curved to cause the junction to merge into the straight part of the arm without leaving any ridge.

The turning connected with the first fixing is now completed, and the object is next put into position for boring the smaller hole. This crank-pin hole is to be either parallel or taper, according to whether the lever is for a middle-shaft or for a paddle-shaft; or whether the lever is to tightly hold a crank-pin's stud-end, or to contain a crank-pin's outer end. If the hole is to be taper the largest end is usually that which adjoins the flat or level side of the lever; consequently, this side must be outwards while on the chuck, as indicated in Fig. 1045. By this Figure it will be seen that one face of the shaft-boss is in direct contact with the chuck, this face having been made parallel with the opposite broad side when the hole was bored. It is therefore necessary to place packing-pieces or wedges between the smaller boss and the chuck, as shown; a holding plate also is shown in contact with the boss face, which need not be removed when other plates and poppets are fastened to the arms, unless the face is to be turned. Through only a comparative small surface of the object being in contact with the chuck at this fixing, it is proper to put a scriber-block upon the chuck with the point to both ends of the gauge-line, in order to ascertain if it is exactly parallel, and to alter it if necessary. Such alteration is easily effected with a wedge driven between the packing-pieces at the small boss, or driven between the packing-pieces in contact with the arm.

The boring required to shape a parallel hole intended for a parallel end of a crank-pin, is the same as the boring for a shaft-hole, being effected with the usual long traverse of the lathe. But a taper hole must be bored without this traverse; and the traverse-gear must be so disconnected as to prevent all possibility of being accidentally put into action by the operator while boring with other means. The means whereby the tool is advanced in the desired direction, is the top slide and screw of the rest; and it is inclined until situate at the proper angle with the centre length of the hole; the exact adjustment being performed after the tool has been a few times through the hole, and partly bored it.

The attachments of poppets for adjusting levers to the exact required places on the chucks, are represented in Figs. 1046 and 1047. In Fig. 1046 a vee-block is shown in contact with the small boss of a lever, so that the vee-gap may firmby grip the boss, and also provide a flat surface for contact with the poppet-screw point, which will move the lever downwards during its adjustment. A couple of poppets must also be put at the other or lower end of the lever, to move it upwards ; and another poppet at each side of the arm, to shift it sideways. The two packing-blocks, denoted by B and B, are parallel ones, and are in contact with the arm's broad side, and are of sufficient thickness to prevent both bosses touching the chuck.

It will be noticed that the lever in Fig. 1046 is one of a class having the two broad sides parallel with each other; such a lever being used for a shaft that requires but one lever to be situate at one extremity, or one lever at each extremity. A lever of this shape is very convenient for fixing ; and if the arm is carefully shaped during the forging, the paring should commence without any preliminary planing of the arm; in which case the smoothly forged broad side is put into contact with the parallel blocks, and is considered a primary plane. When planing is adopted as a first paring, the lever should be adjusted on a table until the bosses and arm's narrow sides are square to the table; in which condition the two broad sides are to be reduced until the arm is of the exact specified thickness. During this planing, the length of the lever is across the length of the table, and at the second fixing no adjusting of the narrow sides square to the table is required, it being only necessary to put parallel blocks in contact with the side first planed. The lever is now ready to be fixed on parallel blocks on a lathe-chuck, for boring both bosses, and for turning both the boss-ends to the exact length required, which length can be accurately measured from the broad sides of the arm, because these were carefully planed to the finished dimensions.

The lever seen in Fig. 1047 is being held tight against the parallel blocks by means of a wood block. This piece is forced tight to the face of the boss with a flat end of a dummy, or of another slide-rest tool, which is advanced against the piece of wood by working the top screw of the rest. By this method a comparative small lever or other article, can be held a short time until additional poppets and plates are attached.