Operator`s manual

Advanced Haas Mill Programming Techniques Training Manual Page 72
The graphics below shows an absolute G90 clockwise positive rotation to an A90 position from A0 position
viewed from the left side.
Left side view of rotary table at A0 (home position) G90 G00 A90 (Absolute A90 Move)
Below left shows an absolute move from A0 to A270. The faster way would be to put the machine in G91
and incrementally move G91 A-90 as shown bottom right. It still presents the A270 side to the spindle.
G90 move to A270 from A0 G91 move of A-90 from A0
If a G91 is used to index the rotary unit a G90 must follow to get the machine back in absolute to use the
correct work offsets for machining. Sometimes the incremental mode is the best for simple indexing. It
gives control over which way the indexing occurs.
The Haas limits the A axis from A-8380. to A8380. The resolution is to .001⁰. Rapid rotations run from 50⁰
per second on large rotary tables to 725⁰ per second on smaller units.