Fig. 1524.
[Fig. 1524] represents an English chuck in which the fixed jaw is composed of two parts, a which is solid with the base g, and d which is pivoted to a at f. The movable jaw also consists of two parts, b which carries the nut for the screw that operates b, and c which is pivoted to b at e. The two pivots e, f being above the surface of the gripping jaws c, d, causes them to force down upon the surface of g as the screw is tightened, the work, if thin, being rested, as in the case of the chuck shown in [Fig. 1523], upon parallel pieces.
Fig. 1525.
[Fig. 1525] represents a chuck made by W. A. Harris, of Providence. The jaws in this case carry two pivoted wings a, b, between the ends of which the work c is held, and the pivots being above the level of the work the tendency is here again to force the work down into the chuck, the strain being in the direction denoted by the arrows.
Here the work rests on four pins which are threaded in the collars h, so that by rotating the pins they will stand at different heights to suit different thicknesses of work, or they may be set to plane tapers by adjusting their height to suit the amount of taper required. The spiral springs simply support the pins, but as the jaws close the pins lower until the washer nuts h meet the surface of recess i.
[Figs. 1526] and [1527] represent Thomas’s patent vice, which possesses some excellent conveniences and features.
