The marking of a key-way or key-bed, at one end of a spindle, is effected with regard to its exact intended position, as in lining for one in a boss, in order that the length of the key-way may be parallel with the length of the spindle, and the width at right angles to a line extending exactly across the spindle's centre, which line is the spindle's minor

2 K2 axis. The line showing this axis should be the one first marked, and if the extremity of the spindle retains its centre recess on which it was lathe-turned and is nearly flat, the line is easily scribed by placing a straight-edge across the centre and scribing a line with a scriber. A line of this sort is shown in Fig. 813, and is also shown in the plan of the extremity which is represented by Fig. 814, being situated across the centre of the spindle-end and extending through the centre of the intended end of the key-way to be made. When it happens that a key-way is to be marked upon the end of a spindle having a curved or pointed end, the marking is done by placing the spindle upon two vee-blocks on a lining-table, in the position shown in Fig. 828, which represents a spindle being scribed with a scriber-block, and without the aid of any centre line resembling that in Fig. 813, for indicating a minor axis. As soon as the spindle's length is adjusted to parallelism with the table, the scriber-block point is applied to the end, and a line is marked along the metal, which line will denote the place of one edge of the intended key-groove. The workman now rotates the spindle a short distance and marks another line, so that the distance between the two shall be equal to the required width, the exact width being denoted by dots previously placed. Such lines will, in all cases, be parallel to each other, parallel to the spindle's major axis, and parallel to the table face, however great the length of them may be, because the spindle was put parallel with the table, and the scriber-point must move in a path which is parallel to the table (see page 111). While the spindle still remains on the vee-blocks, it is also easy to scribe a couple of short lines upon the extremity, to indicate the key-way's width at the end, in addition to showing it along the spindle.

The scribing processes just given will mark the places of key-ways so that their lengths are exactly parallel to the lengths of their respective lever-bosses and spindles or shafts ; and if the scribing were properly done, and the subsequent cutting out also properly done, the key-way of any selected shaft will fit the key-way of that particular lever-boss which was fitted to it, although the two may not have been put into contact with each other during the formation of the key-grooves. But when it is especially desirable to make a key-groove of a spindle exactly fit the key-way of its lever-boss, or wheel-boss, the place for the groove in the spindle should be marked from the key-groove in the boss. This is done by first making the groove in the boss, and next placing the spindle into the hole, that the two may be carefully adjusted to their exact relative positions with each other during their future use. Being thus arranged, the place for the key-groove in the spindle is scribed by moving a scriber along in contact with the edges of the already formed key-way in the boss. For this and similar scribing, a scriber having a short bent end or arm is required, the arm being not too long for any easy movement to and fro in the boss key-way while scribing the spindle.