What is a three jaw chuck?

A three jaw chuck is used to hold a part on a lathe for round work. This part is notable for its protruding grip design that allows it to be used for expanded work.

On a three jaw chuck, all three jaws close or open at the same time, creating a firm symmetrical grip on the part that is going to be worked on. This feature also causes the chuck to be self-centering, which helps ensure professional grade work. This type of chuck is available in a wide variety of sizes and is tightened onto the part using a key.