LinuxCNC M61

M61 sets the current tool number while in MDI or Manual mode without performing a tool change. It is used, for example, when LinuxCNC starts with a tool already in the spindle and the current tool number needs to be set. The Q word gives the tool number and must be 0 or greater.

Source checked5/5 values · 2026-10-26

Specification

1 source

Language	gcode
Code	M61
Syntax	M61 Q-
Dialect	LinuxCNC

Parameters

Name	Description
Q	Tool number to set as current. It is an error if Q is not 0 or greater.

Study notes

M61 changes the current tool number without performing a tool change.
The document gives powering up LinuxCNC with a tool already in the spindle as an example use for M61.

Safety

M61 does not change the tool length offset; use G43 after M61 to change the tool length offset.
It is an error to program Q less than 0.