Operator`s manual

Advanced Haas Mill Programming Techniques Training Manual Page 73
One of the disadvantages with progressive incremental moves in the rotary axes is the accumulation of
large A degree values. If four tools were used on each of the four sides and only incrementally one way
large A values could accumulate: 4 x 4 x 90 = 1440⁰. If the rotary tables is commanded to go home to A0 if
may take a considerable amount of time for the rotary table to unwind itself. Large A values may also
accumulate when long spiral grooves are machined.
To not require extensive time devoted to unwinding the A axis Haas has developed the Quick Rotary G28
feature. If the table is at an A370⁰ the table will just rotate back A-10⁰ with a G28 or a G91 G28 A0
command. It won’t rotate back A-370⁰.
To use this feature Setting #108 must be turned ON. Also, Parameters 43:10 CIRC.WRAP. and 151:10 CIR.
WRAP. must be set to 1.
Central Zero Program Method
Above shows a 4” x 4” cubical fixture (similar to the one shown on page 49) holding 3” x 4” x 1” blocks
where four holes are to be drilled. The rotary head would be to the right. The upper left print gives
dimensions of the part to be drilled. The program zero point in X is the left side of the fixture. The Y and Z
zeros are the center of rotation which lies along the Y axis. Using this method the programmer needs to
add the difference (∆) in each X, Y, Z coordinate from program zero. Then, add the hole locations as shown
in the print in the upper left.
For A0 position ∆X=1.0 ∆Y-1.5 ∆Z=3.0 Lower hole location on top of part X1.5 Y-1.0 Z3.0
For A270 position ∆X=.5 ∆Y=-1.5 ∆Z= 3.0. The lower hole location on top of part X.5 Y-1.0 Z3.0
Although it may make it easier for the operator to set up with only one work offset the programming
becomes much more difficult. If the fixture is not made accurately further corrections need to be made to
the program. The most commonly used method is to have a separate fixture offset for each work piece.