LinuxCNC Axis GUI – Practical Operator Guide (PROBOTIX Version)

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

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1. Machine Coordinates vs Work Coordinates

Machine Coordinates (Absolute Reality)

Defined by homing the machine
Fixed reference based on limit switches
Does not change unless re-homed

Work Coordinates (Your Job Setup)

Defined by the operator
Tells the machine: “This location is X0 Y0 Z0”
Changes for every job

Relationship

Machine Zero (set by homing)
    ↓
Work Offset (G54, G55, etc.)
    ↓
Current Position

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2. Homing (Always Step 1)

What Homing Does

Moves each axis to its switch
Establishs Machine Zero
Enables soft limits and accurate motion

Key Points

Must be done before precision work
Skipping homing = invalid coordinates
Does NOT set part zero

Typical Workflow

Power on
Enable machine
Click Home All

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3. Work Offset System (G54–G59)

LinuxCNC uses standard coordinate systems:

Offset	Use Case
G54	Default (most jobs)
G55–G59	Multiple fixtures / setups

What a Work Offset Stores

X shift
Y shift
Z shift

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4. PROBOTIX Touch-Off System

Standard LinuxCNC	PROBOTIX Version
Touch Off	Set Selected Axis Origin

Additional buttons:

Origin X/Y
Origin Z

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5. Button Functions

Set Selected Axis Origin

Sets selected axis to zero at current position
Used for precise single-axis adjustments

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Origin X/Y

Sets BOTH X and Y = 0

Use when:

You have jogged to your XY reference point

Result:

X = 0
Y = 0

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Origin Z

Sets Z = 0

Why separate:

Tool length changes
Z must be reset per tool
Surface may change during machining

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6. Standard Setup Workflow

Step 1: Home Machine

Home All

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Step 2: Set XY Zero

Jog to desired origin point
Click Origin X/Y

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Step 3: Set Z Zero

Move tool to surface
Click Origin Z

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7. Tool Changes

Key Rule

X and Y stay the same
Z must be reset

Workflow

Change tool
Move to reference surface
Click Origin Z

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8. Z Re-Touch During Jobs

If material has been removed:

Move to a valid reference
Click Origin Z

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9. Common Mistakes

Not homing machine
Forgetting Z after tool change
Using wrong coordinate system (not G54)
Setting origin incorrectly

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10. Conceptual Summary

Homing = Where is the machine?
XY Origin = Where is the part?
Z Origin = Where is the surface for this tool?

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11. PROBOTIX Improvements

Clearer naming vs stock Axis
Faster XY setup
Safer tool-change workflow
Reduced operator error

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12. Quick Reference

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

Homing, Work Offsets, & Touching-off

From PROBOTIX :: wiki

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