LinuxCNC G7

G7 is a LinuxCNC G-code that puts the X axis of a lathe into diameter mode. In diameter mode an X axis move is half the distance to the centre of the lathe, so programming X1 moves the cutter to 0.500" from the centre and produces a 1" diameter part.

Source checked3/3 values · 2026-10-26

Specification

1 source

Language	gcode
Code	G7
Syntax	G7
Dialect	LinuxCNC

Study notes

G7 takes no parameters; it is programmed as a bare G7 on its own line.
G8 Lathe Radius Mode is the opposite mode, but the document gives no reference entry for G8.
G8 is default at power up, so the lathe is in radius mode until G7 is programmed.
G96 constant surface speed is not affected by radius or diameter mode.
In the G76 threading cycle, when G7 is in force the I, J and K values are diameter measurements rather than radius measurements.
Example given in the document: X1 moves the cutter to 0.500" from the lathe centre, giving a 1" diameter part.