$24=200.000 (homing feed, mm/min) – speed of movement for last part of homing cycle.

Last 3 bits set direction for ZYX respectively invert mask: 00000011) – sets direction of travel for homing cycle for each axis.

$22=1 (homing cycle, bool) – enable/disable homing cycle.

$21=0 (hard limits, bool) – enable/disable hard limits (switches).

$20=0 (soft limits, bool) – enable/disable soft limits (numerical entry).

$13=0 (report inches, bool) – Changes the units reporting from mm to inches.

$12=0.002 (arc tolerance, mm) – This setting has to do with how GRBL does arcs by breaking them into many small line segments.

$11=0.020 (junction deviation, mm) – This setting determines the speed algorithm when GRBL approaches a corner.

$10=3 (status report mask: 00000011) – This setting determines what Grbl real-time data it reports back to the user when a ‘?’ status report is sent.

$6=0 (probe pin invert, bool) – inverts the polarity of the Probe input (normally high, active low).

$5=0 (limit pins invert, bool) – inverts the polarity of the limit switch inputs (normally high, active low).

0 = normally low, positive direction, 1 = normally high, negative direction.

$4=1 (step enable invert, bool) – direction of the enable line.

If you motor goes the wrong direction, reverse the setting of the relevant bit. Again, only the last 3 LSB are used, ZYX. port invert mask: 00000011) – Binary mask bits for the direction signal to the stepper driver. 0 = normally low, high pulse, 1 = normally high, low pulse.

$2=1 (step port invert mask: 00000000) – These are binary mask bits that set the polarity of the step pulse.

Setting this to 255 keeps motors always enabled. $1=255(step idle delay, msec) – This is the delay in milliseconds after a move instruction before the stepper motors are disabled.$0=10 (step pulse, usec) – This is the width of the step pulse in microseconds sent to the stepper drive.Each is followed by a quick reference of what it does. We’ll start out with a list of the settings used by GRBL, note that these are settings for a Big Ox type machine with belt drive and 4 axis motors. These internal settings consist of things like customizing the steps/mm of the stepper motor/driver/axis type and setting up the directions and enabling optional features. GRBL has a list of internal variables which must be customized for the machinery connected to the controller. Now that we have GRBL up and running, it’s time to get the settings for GRBL lined up with our machine.

Grbl controller 3.6.1 help