A chuck is a one of the most important devices for holding and rotating a piece of work in a lathe. Short lengths of the work pieces and large diameter or of irregular shapes that cannot be conveniently mounted between the centers are held quickly and rigidly in a chuck. The chuck is attached to the lathe spindle by means of bolts with the back plate screwed on to the spindle nose.
The types of chucks are.
- Four jaw independent chuck
- Combination chuck
- Three jaw universal chuck
- Magnetic chuck
- Collet chuck
- Air or hydraulic operated chuck
- Drill chuck
Four jaw independent chuck:
The four jaw chuck consists of main parts are.
- Concentric circle
- Chuck body
- Jaw screw
- Grinding surface
- Recess for back plates
The four jaw independent chuck has four jaws that may be made to slide within the slots provided in the body of the chuck for gripping different sizes of work piece. Each jaw may be moved independently by rotating the screw that meshes with the teeth cut on the underside of the jaw.
Each jaw is made of tough steel has three inner and one outer gripping surface. The outer gripping surface is used for holding larger sizes of work piece by reversing the jaw. This type of chuck is particularly used for setting of heavy and irregular shaped objects. The diameter of the body specifies the sizes of the chuck.
The combination chuck is consist of main parts are.
- Chuck body
Combination chuck is used as a both a self – centering and an independent chuck to take advantage of both the types. These jaws are operated individually by separate screws or simultaneously by the scroll disc.
The screws are mounted on the frame have teeth cut in its underside that meshes with the scroll and all jaws together with the screws move radially when the scroll is made to rotate by a pinion.