2-Three Jaw Chuck - Advantages
|One may dispute if there are advantages of using a three jaw chuck instead of a four jaw chuck. In truth there are better times to use one vs the other. Since the jaws on a three-jaw chuck all move in unison, centering a cylindrical part is not a concern. The part will run concentric with the chuck, providing that there are no foreign particles between the jaws and the part, or that the chuck is installed on the spindle properly or the chuck has not worn irregularly.
Three jaw chucks are a good choice for handling almost all round objects quickly and securly. If there are a large quantity of parts to machine, and the operations being performed do not require the highest degree of precision or concentricity, then the 3-jaw will be used. It is almost always the prefered chuck.
The jaw faces can also be reversed to accommodate larger diameters. You will notice in the video that the mechanism that moves/guides the jaws is not removed or reversed. The jaw faces are simply reversed and keyed back into place atop the jaw guide.