View source for M04

For CNC machines equipped with a remote activated spindle, the M04 M-Command will activate the spindle in the counter clock-wise direction, also known as '''Spindle Reverse'''. For CNC machines with a pulse width modulated (PWM) spindle, an additional parameter will set the speed, typically calculated in RPM.

It is very important to issue a spindle stop command [[M05]] prior to activating the spindle reverse code. An appropriate [[G04]] dwell command should be used to allow a previously running spindle enough time to slow down and come to a stop. Likewise it is important to issue a dwell command after the spindle has been turned on, to ensure it has enough time to get up to full speed.

 '''Standard Format:'''
 M04 S00000

The S parameter represents the desired speed. Omit the S command if there is no PWM spindle available, it is not required.

==Code Examples==

In this example, the spindle will be turned on clockwise, run for 10 seconds and then turn off with command [[M05]]. After a 5 second wait, we will activate the '''spindle reverse''' run for 5 seconds and then come to a stop.

 M03
 G04 P10.000
 M05
 G04 P5.000
 M04
 G04 P5
 M05

For spindles with a PWM speed control, this example will turn the spindle on and set the speed to 12000 rpm. A [[G04]] dwell command is added to ensure it gets up to speed.

 M04 S12000
 G04 P5.000

[[Category: G-Code]] [[Category: M-Commands]]