HEIDENHAIN TNC 320 User Manual page 121

Please note while programming:
Program a positioning block for the starting point (stud
center) in the working plane with radius compensation R0.
The offset required before countersinking at the front
should be determined ahead of time. You must enter the
value from the center of the stud to the center of the tool
(uncorrected value).
The algebraic sign of the cycle parameters depth of thread
or sinking depth at front determines the working direction.
The working direction is defined in the following
sequence:
1st: Depth of thread
2nd: Depth at front
If you program a depth parameter to be 0, the TNC does
not execute that step.
The algebraic sign for the cycle parameter thread depth
determines the working direction.
Danger of collision!
Use the machine parameter displayDepthErr to define
whether, if a positive depth is entered, the TNC should
output an error message (on) or not (off).
Keep in mind that the TNC reverses the calculation for pre-
positioning when a positive depth is entered. This
means that the tool moves at rapid traverse in the tool axis
to set-up clearance below the workpiece surface!
HEIDENHAIN TNC 320 121