HEIDENHAIN TNC 320 User Manual page 109

Please note while programming:
Before programming, note the following:
Program a positioning block for the starting point (hole
center) in the working plane with radius compensation R0.
The algebraic sign of the cycle parameters depth of thread,
countersinking depth or sinking depth at front determines
the working direction. The working direction is defined in
the following sequence:
1st: Depth of thread
2nd: Countersinking depth
3rd: Depth at front
If you program a depth parameter to be 0, the TNC does
not execute that step.
If you want to countersink at front, define the
countersinking depth as 0.
Program the thread depth as a value smaller than the
countersinking depth by at least one-third the thread pitch.
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 320 109