There are two basic flavors to using the 4th axis. One is rotating the part to a new orientation and doing 3D operations at that new orientation . The second is doing a rotation operation that cuts while the A axis rotates.Originally Posted by MetalShavings
For the first type, part of the job assignment parameters you can set is the rotation of the A axis. Say, for example, your part has a top set of holes, and a set of holes at 90 degrees. You would setup two hole machining operations. The top operation would be at A=0. The next operation would set the A axis to 90. Note that when you add the A axis, a new step needs to be added to your pre-start routine at the machine. You need to setup the A axis on the machine by finding zero for A.
The second type of operation which is rotation cutting is best done watching a tutorial first. Check the Tormach site for SprutCAM tutorials