Oftentimes work can neither be suspended between centers nor bolted to the face plate. In this case it is held by a chuck, a type of which is shown in Fig. 176. The four jaws (one of which is marked B) may be adjusted in a radial direction by a wrench on one of the nuts C. This nut is the end of a radial screw. The jaws grip the work by clamping down on it or by pressing out against the inside of hollow work of large diameter. The jaws may be turned end for end to secure work in the two ways just designated.

Chucks have usually three jaws or four jaws, and they are classed as independent or universal. The jaws of an independent chuck are moved separately by the wrench, while the jaws of the universal chuck have their controlling screws so connected by an internal mechanism as to make then move outward or inward together. Many chucks are made to be changed by a clamp and screw from universal to independent and vice versa. Chuck jaws may be fitted to slotted face plates.

Fig. 176.   Lathe Chuck.

Fig. 176. - Lathe Chuck.

Fig. 177.   Work Mounted on Lathe Mandrel.

Fig. 177. - Work Mounted on Lathe Mandrel.