LinuxCNC G98

G98 is a G-code that selects the retract level used at the end of canned cycles such as drilling and boring. In this mode the tool returns to the Z position it held just before the series of contiguous canned cycles began, if that position is higher than the R value; otherwise the R value is used. It is the alternative to G99, which always retracts to the R position.

Source checked2/2 values · 2026-10-26

Specification

1 source

Language	gcode
Code	G98
Group	Canned Cycle Return Level
Dialect	LinuxCNC

Study notes

G98 retracts to the position the axis was in just before the series of one or more contiguous canned cycles was started, provided it is higher than the R value; if lower, the R value is used.
G99 instead retracts to the position specified by the R word of the canned cycle.
G98 is also referred to in the document as OLD_Z retract mode.
The initial (G98) plane is reset any time cycle motion mode is abandoned, whether explicitly with G80 or implicitly with any motion code that is not a cycle.
Switching among cycle modes (for example G81 to G83) does not reset the initial plane.
It is possible to switch between G98 and G99 during a series of cycles.
Documented example: G0 X1 Y2 Z3 followed by G90 G98 G81 X4 Y5 Z-0.6 R1.8 F10 returns to Z3 because it is higher than the R value of 1.8.