4. INTERPOLATION FUNCTIONS
Specifying an increment or a decrement value for a lead per screw
revolution enables variable–lead thread cutting to be performed.
Fig. 4.9 (a) Variable–lead screw
: End point
F : Lead in long
itudinal axis direction at the start point
K : Increment and decrement of lead per spindle revolution
Address other than K are the same as in straight/taper thread cutting with
Table 4.9 (a) lists a range of values that can be specified as K.
Table 4.9 (a) Range of valid K values
Metric input 0.0001 to 500.0000 mm/rev
Inch input 0.000001 to 9.999999 inch/rev
P/S alarm (No. 14) is produced, for example, when K such that the value
in Table 4.9 (a) is exceeded is directed, the maximum value of lead is
exceeded as a result of increase or decrease by K or the lead has a negative
The “Thread Cutting Cycle Retract” is not effective for G34.
Lead at the start point: 8.0 mm
Lead increment: 0.3 mm/rev
G34 Z–72.0 F8.0 K0.3 ;