Specifications

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CONCISE GUIDE FANUC 35

3.11 “G33” THREAD CUTTING MOVEMENTS

Function G33 is used for separate thread cutting movements.

In fact, G33 differs from G1 since the tool starts the working movement only when the control receives the

“spindle in position” signal from the encoder, which allows the tool to work in synchronisation with the

spindle (for this reason the NC offers the possibility to cut workpieces already threaded several times,

obviously without changing the gripping position).

The block with G33 may contain these instructions:

G33 final point (X or Z) feed (F) starting angle (Q)

The starting angle of the thread cutting can be programmed with address Q from 0° to 360000°

(thousandths value).With the programming of a thread cutting starting angle it is possible to machine

multi-start threads without moving the starting point along axis Z. If no starting angle is programmed, the

NC assumes an angle of 0° as the starting value .

When machining threads, the axis and spindle trimmers are “frozen” at 100% of the programmed speed.

Example:

N1 T1 (Thread cutting)

N2 G97 S1300 M3

N3 G0 X29.5 Z5 M8

N4 G33 Z-26 F1.25

N5 G0 X32

N6 Z5

N7 X29.2

N8 G33 Z-26 F1.25

N9 G0 X32

N10 Z5

N11 …..

Example of multi-thread machining :

M30x1.25