Siemens Sinumerik 840D sl Programming Manual page 229

An arc is also specified. As for G2/G3, this can be programmed via the center point, radius,
opening angle or intermediate point specification (see "Circular interpolation (Page 178)").
When programming the convex thread with center point programming, the following must be
taken into account: Since I, J and K are used for the pitch in thread cutting, the circle
parameters in the center point programming must be programmed with IR=..., JR=... and
KR=....
IR=...:
JR=...:
KR=...:
Note
IR, JR and KR are the default values of the interpolation parameter names for a convex thread
that can be set via machine data (MD10651 $MN_IPO_PARAM_THREAD_NAME_TAB).
Differences to the default values must be taken from the specifications of the machine
manufacturer.
Optionally, a starting point offset SF can also be specified (see "Thread cutting with constant
lead (G33, SF) (Page 214)").
Syntax
The syntax for the programming of a convex thread therefore has the following general form:
G335/G336 <axis target point coordinate(s)> <pitch> <arc> [<starting
point offset>]
Examples
Example 1: Convex thread in the clockwise direction with end and center point programming
Program code
N5 G0 G18 X50 Z50
N10 G335 Z100 K=3.5 KR=25 IR=-20 SF=90
Fundamentals
Programming Manual, 01/2015, 6FC5398-1BP40-5BA2
Cartesian coordinate for the circle center point in the X direction
Cartesian coordinate for the circle center point in the Y direction
Cartesian coordinate for the circle center point in the Z direction
Motion commands
10.10 Thread cutting
Comment
; Approach starting point.
; Turn convex thread in the clock-
wise direction.
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