B-63324EN/03 PROGRAMMING 13.FUNCTIONS TO SIMPLIFY PROGRAMMING
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13.1.2 Left-handed Tapping Cycle (G74)
This cycle performs left-handed tapping.
In the left-handed tapping cycle, when the bottom of the hole has been
reached, the spindle rotates clockwise.
Point R level
G74 X_ Y_ Z_ R_ P_ F_ L_ ;
X_Y : Hole position data
Z : The distance from point R to the bottom of the hole
R_ : Initial time
P : Dwell time
F_ : Cutting feedrate
L_ : Number of repeats (if required)
Tapping is performed by turning the spindle counterclockwise. When
the bottom of the hole has been reached, the spindle is rotated
clockwise for retraction. This creates a reverse thread.
Feedrate overrides are ignored during left-handed
tapping. A feed hold does not stop the machine until
the return operation is completed.
By setting bit 1 (DWL) of parameter No. 6200 to 1, dwell is performed
for the duration specified with P before forward or reverse spindle
rotation. This function is useful when a special tapper is used. (While
dwell operation is being performed with no movement made along the
Z-axis, a tapper performs forward/backward movement for threading
only with a rotational force.)