HEIDENHAIN TNC 320 User Manual page 149

Please note while programming:
Pre-position the tool in the machining plane to the starting
position with radius compensation R0. Note parameter
Q367 (stud position).
The TNC automatically pre-positions the tool in the tool
axis. Note parameter Q204 (2nd set-up clearance).
The algebraic sign for the cycle parameter DEPTH
determines the working direction. If you program
DEPTH=0, the cycle will not be executed.
At the end, the TNC positions the tool back to the set-up
clearance, or to the 2nd set-up clearance if one was
programmed.
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!
Leave enough room next to the stud for the approach
motion. Minimum: tool diameter + 2 mm
HEIDENHAIN TNC 320 149