Siemens SINUMERIK 840D Programming Manual page 72

Drilling Cycles and Drilling Patterns 03.96
2 2
2.1 Drilling cycles
MPIT and PIT (as thread size and as value)
The parameter for the spindle pitch only has a meaning
if tapping is performed with encoder. The cycle
calculates the feedrate from the spindle speed and the
pitch.
The value for the thread pitch can either be defined as
the thread size (for metric threads between M3 and M48
only) or as a value (distance from one thread turn to the
next as a numerical value). The parameter not required
in each case is omitted from the call or assigned the
value zero.
If the two thread pitch parameters have conflicting
values, alarm 61001 "Thread pitch wrong" is generated
by the cycle and cycle execution is aborted.
Further notes
Depending on the setting in machine data
NUM_ENCS, the cycle selects whether tapping is to
performed with or without encoder.
The direction of rotation for the spindle must be
programmed with M3 or M4 before the cycle is
called.
In thread blocks with G63, the values of the feedrate
override switch and spindle speed override switch
are frozen at 100%.
A longer compensating chuck is usually required for
tapping without encoder.
 Siemens AG 2000 All rights reserved.
2-72
SINUMERIK 840D/840Di/810D/FM-NC Programming Guide, Cycles (PGZ) - 04.00 Edition