Page:The American Cyclopædia (1879) Volume IV.djvu/717

 CLOCKS AND WATCHES 705 pany at Boston, Mass. ; the United States watch company at Marion, N. J. ; the National watch company at Elgin, 111. ; the New York watch company at Springfield, Mass. ; the Spring- field watch company at Springfield, 111. ; and the Cornell Watch company at Grand Cross- ing, 111. Watches made by this method possess the advantage of great accuracy at a compara- tively small cost. All the parts in the train are made perfectly uniform, so that any particular wheel may be replaced without making any sensible variation in the running of the watch ; and so of any other part. The small, fine- threaded screws which are used to hold some of the parts together are made in the most perfect manner and with wonderful rapidity by very ingenious machines, one of which is shown in fig. 17. A steel wire, a, is placed in FIG. 17. Screw Lathe. the spindle and turned by the belt. A die, represented enlarged in the upper part of the cut, made in two sections and held in the end of a tool 5, cuts the thread as it is pressed against the.wire by a motion communicated by a lever. Previous to this, however, the wire is reduced to the precise length required by the tool e, which is adjusted by a gauge, and the stem of the screw is also turned down by the tool d. After the thread is cut, the tool e is brought against the wire, and the head of the screw is formed. There is an ingenious device for removing the screw, which is still attached to the wire by a small pedicle. It consists of two disks, represented in fig. 18, which when joined together form a series of tapped holes, made to fit the screws. One of these, being held against the point of the screw while it is revolv- ing in the spindle, receives it, and when the end of the thread is reached the motion breaks off the pedicle, leaving the screw in the disk. When all the holes are filled, the disk is placed in an ingenious automatic machine which car- FIG. 18. Slotting Disk. ries, during proper periods of time, the head of each screw beneath a revolving saw which cuts the slot. A machine for cutting the teeth in wheels is shown in fig. 19. A tool called a quill, an enlarged view of which is presented FIG. 19. Lathe for Cutting Teeth. in fig. 20, a, and which is divided into sections to receive the arms of the wheel, bearing upon its exterior the rim, is fed with from 20 to 40 wheels, the collection being called a stack. This quill is then placed upon a shaft which is turned by a graduated wheel having notches in its rim to correspond with the number of teeth in the wheel. This wheel is stopped at each notch by the click c, whereby the quill holding the stack of wheels is fixed, and in such a position FIG. 20. Enlarged View of Cutter. respecting the tool which is carried by the arbor &, that a groove may be cut between two teeth in a radial direction, or any other which may be required. The arbor of the cutting tool is carried backward and forward by means of a slide <Z, worked by a lever e, by which means the tool is carried along the whole length of the stack of wheels, cutting a notch in each, and thereby forming the teeth. Club- tooth scape wheels require for their cutting several different forms of tools. These are