17 Canned Cycles for Drilling
17.1.2 Counter Tapping Cycle (G74)
Fig.
This cycle can be used only with a spring tap. The variables used in the cycle are G17 G74 Xp__ Yp__ Zp__ R__ (P__) F__ L__
G18 G74 Zp__ Xp__ Yp__ R__ (P__) F__ L__ G19 G74 Yp__ Zp__ Xp__ R__ (P__) F__ L__
Prior to start the cycle, the spindle has to be started or programmed to rotate in the direction of M4
The value of feed has to be specified in conformity with the thread pitch of the tapper.
– In state G94 (feed per minute):
where P is the thread pitch in mm/rev or inches/rev, S is the spindle speed in rpm
– In state G95 (feed per revolution):
where P is the thread pitch in mm/rev or inches/rev. The operations of the cycle:
1.
2.-
3.
4.-
5.drilling as far as thebottom point, with feed F (override and stop inhibited)
6.dwell with the value specified at address P, provided parameter TAPDWELL is enabled (=1) spindle direction reversal (M3)
7.retraction as far as point R with feed F (override and stop inhibited)
8.spindle direction reversal (M4)
9.with G98,
10.-
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