LinuxCNC G74 Left-hand Tapping Cycle with Dwell

G74 is a LinuxCNC G-code cycle for left-hand tapping with a floating chuck. It moves the Z axis at the programmed feed rate to the Z position, stops the selected spindle, starts clockwise spindle rotation, dwells for P seconds, and feeds back to clear Z. The document states that G74 does not use synchronized motion.

Source checked19/19 values · 2026-10-26

Specification

1 source

Language	gcode
Code	G74
Syntax	G74 (X- Y- Z-) or (U- V- W-) R- L- P- $- F-
Dialect	LinuxCNC

Parameters

Name	Description
X
Y
Z
U
V
W
R	Retract position along the Z axis.
L	Used in incremental mode; number of times to repeat the cycle. See G81 for examples.
P	Dwell time (seconds).
$	Selected spindle.
F	Feed rate (spindle speed multiplied by distance traveled per revolution (thread pitch)).

Study notes

The feed rate F is spindle speed multiplied by distance per revolution (thread pitch); the document gives S100 with 1.25 mm per revolution as F125.
The L word is used in incremental mode to repeat the cycle; the document refers to G81 for examples.
The G74 cycle uses preliminary and in-between motion from the canned cycle motion section.

Safety

Warning: G74 does not use synchronized motion.
Feed and speed overrides are disabled during the G74 cycle and restored after it finishes.