HEIDENHAIN TNC 426 (280 476) - Manual (Page 267)

240 8 Programming: Cycles
8.3 Cy
cles f
o
r Dr
illing, T
a
pping and Thr
ead Milling
11 At the end of the cycle, the TNC retracts the tool in rapid traverse
to set-up clearance or, if programmed, to the 2nd set-up clearance
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 wish to countersink with the front of the tool, 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.