What is the number of jaws in self-centred chuck?

Explanation:

Three Jaw Chuck:

• It is also known as three jaws universal chuck, self-centering chuck, and concentric chuck having three jaws that work at the same time.
• The 3 jaws, which are generally made of high-quality steel, are arrogated at an angle of 120° to each other. During the operation, the jaw teeth are made to mesh with scrawl spiral teeth (Bevel’s teeth).
• The meshing causes a moment of all 3 jaws either towards or away from the chuck center, depending upon the direction of rotation of the bevel pinion.
• Three jaw chucks are used to hold only perfect round and regular jobs, workpieces of circular and hexagonal shapes.

Four Jaw Chuck:

• The four-jaw chuck is also called an independent chuck since each jaw can be adjusted independently.
• Four jaw chucks are used for a wide range of regular and irregular shapes.