View source for Homing, Work Offsets, & Touching-off

= LinuxCNC Axis GUI – Operator Guide (PROBOTIX Version) =

This guide explains how '''homing, work offsets, and touch-offs''' work together using the PROBOTIX-customized Axis interface.



== Axis Interface Overview ==

[[File:axis-probotix_ui.jpg|800px]]

'''Key Areas:'''

# '''Manual Control Panel (Left)'''
#* Axis selection (X / Y / Z)
#* Jog controls
#* '''Set Selected Axis Origin'''
#* '''Origin X/Y'''
#* '''Origin Z'''
# '''Preview Window (Right)'''
#* Displays toolpath and machine position
#* Shows X, Y, Z coordinates
# '''DRO (Digital Readout)'''
#* Shows current position in active coordinate system (typically G54)
# '''Status Bar (Bottom)'''
#* Active coordinate system (G54)
#* Tool status
#* Machine state



== Machine Coordinates vs Work Coordinates ==

[[File:coordinate_systems.jpg|700px]]

'''Machine Coordinates (HOME)'''
* Set by homing the machine
* Fixed reference point
* Does not change unless re-homed
* Represented by the G53 coordinate system

'''Work Coordinates (G54 - G59.3)'''
* Nine possible coordinate systems (G54, G55, G56, G57, G58, G59, G59.1, G59.2, G59.3)
* Set by the operator
* Defines where the part is located
* Changes for every setup
* Can be used for repeatable fixture placement for production parts to make setup easier

'''Concept:'''
<pre>
     Machine Zero (HOME)
         ↓
     Work Offset (G54)
         ↓
     Current Position
</pre>

== Homing (Required Before Operation) ==

'''What Homing Does:'''
* Moves each axis to its switch
* Establishes Machine Zero (HOME)
* Enables accurate motion and limits

'''Important:'''
* '''Required before running any G-code program'''
* '''Required before executing MDI commands'''
** (Many UI buttons execute MDI commands internally)
* Homing only needs to be done once per software session

'''Re-home whenever:'''
* The machine has been powered off and turned back on
* The machine crashes or loses position
* The control software is restarted
* You are unsure of machine position

'''Important:'''
* Stepper motors do not retain exact position when powered off
* On power-up, motors may shift slightly as they energize
* On dual-motor axes (such as Y), this can introduce slight gantry skew
* Homing re-squares the machine and restores accurate machine coordinates

{{Warning|
You MUST home the machine after every power cycle. Stepper motors do not maintain exact position when powered off. 
Failure to re-home can result in positional errors or gantry misalignment, especially on dual-motor axes.
}}

=== Procedure ===
# Power on machine
# Enable machine
# Click '''Home All'''

{{Warning|
You will not be able to run a program or use interface buttons before homing.
The machine position is unknown until homed.
}}



== Work Offset System (G54-G59.3) ==

LinuxCNC uses coordinate systems:

{| class="wikitable"
! Offset !! Use Case
|-
| G54 || Default (most jobs)
|-
| G55-G59.3 || Multiple fixtures or setups
|}

'''A work offset stores:'''
* X shift
* Y shift
* Z shift



== Setting Work Zero (PROBOTIX Workflow) ==

[[File:axis-probotix_ui.jpg|800px]]

=== Step 1: Set XY Origin ===

# Jog to desired XY location on your part
# Click '''Origin X/Y'''

Result:
<pre>
     X = 0
     Y = 0

</pre>

=== Step 2: Set Z Origin ===

# Move tool to material surface
# Click '''Origin Z'''

Result:
<pre>
     Z = 0

</pre>

=== Step 3: Fine Adjustment (Optional) ===

Use '''Set Selected Axis Origin''' for:
* Single-axis adjustments
* Precision corrections
* When using edge finders, probes, or spacers to accurately locate edges or surfaces


== Manual Tool Changes (Critical) ==

'''Key Rule:'''
* X and Y stay the same
* Z must be reset

=== Workflow ===
# Change tool
# Move tool to reference surface
# Click '''Origin Z'''

{{Warning|
After changing tools, you MUST re-set Z using '''Origin Z'''.

Failure to do so will result in incorrect cutting depth or machine crashes.
}}



== Z Re-Touch Between Manual Tool Changes ==

If material has been removed or surface changes:

# Jog to a valid reference location
# Click '''Origin Z'''



== What You Are Actually Doing ==

* '''Homing''' → Defines where the machine is
* '''Origin X/Y''' → Defines where the part is
* '''Origin Z''' → Defines tool height for the current tool



== Common Mistakes ==

* Not homing before running a program
* Running MDI commands before homing
* Forgetting to re-set Z after manual tool changes
* Using the wrong coordinate system (not G54)
* Setting origin incorrectly



== Quick Reference ==

<pre>
STARTUP:
    Home All

SETUP:
    Jog to XY → Origin X/Y
    Touch Z → Origin Z

TOOL CHANGE:
    Change tool
    Re-touch Z → Origin Z

RUN:
    Cycle Start
</pre>