thinkyhead

M851 - XYZ Probe Offset

none Set the Z probe XYZ offset from nozzle HAS_BED_PROBE

Description

Set the XYZ distance from the nozzle to the probe trigger-point.

The easiest way to get the Z offset value is to:

  • Home the Z axis.
  • Raise Z and deploy the probe.
  • Move Z down slowly until the probe triggers.
  • Take the current Z value and negate it. (5.2 => -5.2)
  • Set with M851 Z-5.2 and #define Z_PROBE_OFFSET_FROM_EXTRUDER -5.2.

For X and Y you have to measure the distance.

Notes

The default (factory) values are set by

  • X_PROBE_OFFSET_FROM_EXTRUDER
  • Y_PROBE_OFFSET_FROM_EXTRUDER
  • Z_PROBE_OFFSET_FROM_EXTRUDER

and are integer values.

Positions:
X offset: -left +right [of the nozzle]
Y offset: -front +behind [the nozzle]
Z offset: -below +above [the nozzle]

   +-- BACK ---+   
   |           |   
 L |    (+) P  | R <-- probe (20,20)   
 E |           | I   
 F | (-) N (+) | G <-- nozzle (10,10)   
 T |           | H   
   |    (-)    | T   
   |           |   
   O-- FRONT --+   
 (0,0) 

Usage

M851 [X<linear>] [Y<linear>] [Z<linear>]

Parameters

[X<linear>]

Z probe X offset

[Y<linear>]

Z probe Y offset

[Z<linear>]

Z probe Z offset

Examples

Set a reasonable offset for an inductive probe

M851 Z-2.0 

A probe that is triggered by the nozzle itself

M851 Z1.2 

Set the XY distance (probe left front of nozzle)

M851 X-1.70 Y-1.30 

Set the XY distance (probe right back of nozzle)

M851 X0.20 Y.40