Fig. 1829.
In [Fig. 1829] is represented a bolt threading machine or bolt cutter, which consists of a head carrying a live spindle upon which is a head carrying four bits or chasers that may be set to cut the work to the required diameter, and opened out after the work is threaded to the required length and the bolt withdrawn without losing the time that occurs when the dies require to run backward to release the work, and also preventing the abrasion and wear that occurs to the cutting edges of the die bits or chasers when revolved backward upon the work. This head is operated by the upright lever shown in the figure, this lever being connected to the clutch shown upon the live spindle. The details of construction of the clutch and of the head are shown in [Figs. 1830], [1831], [1832], and [1833]. The work to be threaded is gripped between jaws operated by the large hand wheel shown, while the vice moves the work up to or away from the head by means of the small hand wheel which operates pinions geared with racks on each side of the bed of the machine as clearly shown in the figure.
Fig. 1830.
Fig. 1831.
[Fig. 1830] is a longitudinal section of the head, and [Fig. 1831] an end view of the same. p are the threading dies or chasers held in slots in the body a by the annular ring face plate k. The ends of the dies are provided with T-shaped caps t fitting into corresponding grooves or slideways in the die ring b, and it is obvious that as the heads of their caps are at an angle therefore sliding the ring b along a and to the right of the position it occupies in the figure will cause the dies p to close concentrically towards the centre or axis of the head a. At c is a ring capable of sliding upon a and operated by the upright lever shown in the general view in [Fig. 1829].