Actions

Homing, Work Offsets, & Touching-off

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Revision as of 17:03, 4 May 2026 by Admin (Talk | contribs) (Setting Work Zero (PROBOTIX Workflow))

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.

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Axis Interface Overview

Axis-probotix ui.jpg

Key Areas:

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

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Machine Coordinates vs Work Coordinates

Coordinate systems.jpg

Machine Coordinates (HOME)

  • Set by homing the machine
  • Fixed reference point
  • Does not change unless re-homed

Work Coordinates (ZERO / G54)

  • Set by the operator
  • Defines where the part is located
  • Changes for every setup

Concept:

Machine Zero (HOME)
    ↓
Work Offset (G54)
    ↓
Current Position

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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 if:

  • The machine crashes or loses position
  • Steps are skipped
  • Power is lost while moving
  • The control software is restarted
  • You are unsure of machine position

Procedure

  1. Power on machine
  2. Enable machine
  3. Click Home All


Warning WARNING:

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


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Work Offset System (G54-G59.3)

LinuxCNC uses coordinate systems:

Offset Use Case
G54 Default (most jobs)
G55-G59.3 Multiple fixtures or setups

A work offset stores:

  • X shift
  • Y shift
  • Z shift

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Setting Work Zero (PROBOTIX Workflow)

Axis-probotix ui.jpg

Step 1: Set XY Origin

  1. Jog to desired XY location on your part
  2. Click Origin X/Y

Result:

X = 0
Y = 0

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Step 2: Set Z Origin

  1. Move tool to material surface
  2. Click Origin Z

Result:

Z = 0

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Step 3: Fine Adjustment (Optional)

Use Set Selected Axis Origin for:

  • Single-axis adjustments
  • Precision corrections

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Manual Tool Changes (Critical)

Key Rule:

  • X and Y stay the same
  • Z must be reset

Workflow

  1. Change tool
  2. Move tool to reference surface
  3. Click Origin Z


Warning 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.


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Z Re-Touch Between Manual Tool Changes

If material has been removed or surface changes:

  1. Jog to a valid reference location
  2. Click Origin Z

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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

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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

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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