Manual

Thread Cutting
Chapter 25
2
5
-
1
3
Where : Is :
E F This parametermay beentered byusing either an E- or F-word. It represents the
thread lead along the axis withthe largest programmed distance to travel to
make the thread cut. It is mandatory whencutting any threads.
If the E-word is programmed, itsvalue (signignored) isequal to the number of
threads perinch orinches perthread (determinedin AMP)regardless of whether
inch or metric mode is active at the time.
If the F-word is programmed, itsvalue (signignored) isthe threadlead ininches
per revolutionor millimeters per revolution, dependingon themode inwhich the
control isoperating.
In a G34 block, E or F indicatesthe initialthread lead used at the start of the
threading pass.
Q This optionalparameter provides arelative valuefor the start offset angle of the
thread. Its primary useis incutting multistart threads. For example, if a
threading pass were madewith avalue of zero here, and then followedby
another passwith avalue of 180°, thenthe secondcut would bestarted 180°
from thefirst resulting ina two-start thread. If two morepasses arethen made
(one with an a parameter valueof 90° and onewith avalue of 270°), the result
would be a four-start thread.
K Program the difference in the thread leadper spindle revolution(inch/rev/rev or
mm/rev/rev). The amount of K isadded tothe threadlead (Eor F) after each
thread is cut. K maybe programmedas apositive (increasingthread lead) ora
negative (decreasing thread lead) value.
The lead changes continuously during the move. At any point during the
move, you can calculate the lead with this formula:
instantaneous lead = F + (K * number of revs since the start)
Figure 25.10
Instantaneous Lead
Revolutions
K *Revs
F
Lead
Distance
The actions of the G34 variable lead threading operation are identical to
the G33 threading operation with the exception of the variable thread lead.
See the G33 threading section for details and examples of single-pass
threading blocks that cut parallel, tapered, or face threads.