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

Number of Jaws required for self centred chuck is three, thus it is used for centrering symmetrical workpieces. For unsymmetrical workpiece we require Four-Jaw chuck.

A lathe chuck is a holding device which is used for holding the job firmly against the cutting tool.

There are two types of chuck:

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

Three Jaw Chuck:

It is also known as three jaws universal chuck, self-centring chuck and concentric chuck having three jaws which work at the same time. Three jaw chucks are used to hold only perfect round and regular jobs