When 3 Jaws are Better than 4

When it comes to precision turning, three-jaw scroll chucks are not on the short list of machinists in front of lathes at shops around the globe. Or are they? Depending on the type of three-jaw chuck and the level of precision required, they certainly should be! Allow me to elaborate.

I am willing to bet that all of you reading this have, at some point in time, needed to use a four-jaw independent chuck to dial in a part to run true and concentric. This may have been in your educational years, like me, or in your professional careers.

I’m also sure that most of us have run into this utterly annoying situation: While adjusting one of the jaws you cause the chuck to lose its grip and your part ultimately falls into the chip bed or onto the ways. Just writing that line makes me shudder.