Hydraulic 3-Jaw Chuck
This chuck is incredibly versatile, and the hardened steel "hard jaws" can be changed out for unhardened "soft jaws" which can be bored out to suit the part you are working on.
The chuck jaws are held in place with 90-degree V-serrations. Loosening the two bolts that hold each jaw on - but not removing them completely - will allow you to move the jaws out the appropriate amount to clamp your stock. To help get you in the right ball park and well aligned you can count the number of serrated teeth that protrude from the edge of the chuck and ensure that all jaws have the same number.
Clamping Indicator
In the centre of Jaw 1 there is a clamping indicator. When the jaws are adjusted correctly and the chuck is in the clamped position the marker line must be in the centre box area, ideally the closer to the centre of the box the better.
Soft jaws
When it is necessary to hold parts very delicately you may wish to use custom-turned softjaws. These are made from unhardened steel.
Removing and remounting the 3-jaw chuck
You must not try to change the chuck or workholding yourself - a member of technical staff will do it for you. It is very easy to cause many thousands pounds of damage while changing the chucks on the lathe.
Information in this section is for reference only, and to assist the technical staff.
Haas provide this video guide for changing the chuck on their CNC lathes.