An adjustable chuck apparatus for a screw tap comprising:
- a torque limiting device including an inner grasping member, a positioning member, and a torque transmitting mechanism wherein the torque transmitting mechanism is disposed in the positioning member and passes through the inner grasping member, and the positioning member includes a projecting threaded shank configured to fasten in the inner grasping member;
- the torque transmitting mechanism including a projection, a cylindrical element spaced from the projection, a truncated conic member at one end of the projection distal the cylindrical element, and a hole through the truncated conic member;
- a chuck including a transverse channel, an externally threaded protrusion at one end, a truncated conic first hole through the externally threaded protrusion to communicate with the transverse channel, a second hole at the other end and communicating with the transverse channel, the second hole being shaped to complimentarily receive the truncated conic member, and a lateral first hole member extending from an outer surface to the transverse channel;
- a threaded fastener;
- a pin;
- a first positioning member including a threaded tunnel;
- a second positioning member including a threaded tunnel;
- a barbell shaped interconnection member including a first externally threaded section at one end and threadedly fastened in the threaded tunnel of the first positioning member, a second externally threaded section at the other end and threadedly fastened in the threaded tunnel of the second positioning member, an intermediate bar interconnected to the first externally threaded section and the second externally threaded section, and a hole element through the second externally threaded section;
- a truncated conic collet including a plurality of grasping elements arranged as a disc, each grasping member having two hole units on an inner surface and a trough between the hole units, a plurality of biasing members each biased between the adjacent hole units of two adjacent grasping elements, and a passage formed by the troughs;
- and
- a cap including an opening and a threaded inner surface;
- wherein the threaded fastener is driven through the first hole, the transverse channel, the second hole and the hole to secure to the torque transmitting mechanism, thereby fastening the chuck and the torque transmitting mechanism together;
- the interconnection member, secured to both the first positioning member and the second positioning member, is disposed in the transverse channel;
- the pin is inserted into the first hole member to urge against the intermediate bar;
- the collet is disposed in the threaded inner surface of the cap to urge against the opening of the cap;
- and
- the threaded inner surface of the cap is secured to the externally threaded protrusion to secure the cap and the chuck together.