Eddy NG Multi-Point Thermal Stability Verification for Klipper

A lightweight control system for Klipper that uses an Eddy current probe (e.g. Eddy NG) to verify bed thermal stability and warp convergence before printing.

Instead of relying on fixed heat soak times, this system:

• Measures real bed deformation
• Tracks multi-point drift over time
• Detects true thermal equilibrium
• Exits early when stabilization is reached

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🚀 Features

• ✅ 5-point bed sampling (center + corners)
• ✅ Drift-based stability detection
• ✅ Smart early-exit (trend-aware)
• ✅ Non-blocking control loop (delayed_gcode)
• ✅ Clean integration into START_PRINT

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🧠 System Overview

🔄 High-Level Flow

Start Macro
    ↓
Initial Probe (5 points)
    ↓
Store baseline
    ↓
Loop:
    ↓
  Probe again
    ↓
  Calculate drift + trend
    ↓
 ┌───────────────┬───────────────┐
 │ Not Stable    │ Stable        │
 │               │               │
 ↓               ↓               ↓
Repeat Loop   Early Exit     Final Exit

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📊 Logic Flow

flowchart TD
    A[Start VERIFY_BED_STABILITY_MULTI] --> B[Heat Bed]
    B --> C[Initial 5-Point Probe]
    C --> D[Store Baseline]

    D --> E[Loop Start]
    E --> F[Probe 5 Points Again]
    F --> G[Compute Max Drift]
    G --> H[Compute Trend]

    H --> I{Stable?}

    I -->|Yes| J[Increment Stable Count]
    I -->|No| K[Reset Counter]

    J --> L{Stable Count >= Required?}
    L -->|Yes| M[Exit: Fully Stable]
    L -->|No| N[Continue Loop]

    K --> O{Early Exit Condition?}
    O -->|Yes| P[Exit: Smart Stabilized]
    O -->|No| N

    N --> E

Loading

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📍 Probe Layout

  (Xmin,Ymax)      (Xmax,Ymax)

         ●  (Center)

  (Xmin,Ymin)      (Xmax,Ymin)

• 5-point sampling detects:

  • Warp
  • Improved Bed Stability Verification
  • Uneven expansion

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📦 Installation

1. Download And Add Config File

Download the config file and put in the config folder: https://github.com/wildBill83/bed_checker/blob/main/bed_check.cfg

~/printer_data/config/bed_check.cfg

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2. Include in printer.cfg

[include bed_check.cfg]

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3. Customize Macros

Open the .cfg file and read through it to customize to you liking using the following parameters.

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⚙️ Configuration

Key Parameters

Parameter	Default	Description
BED_TEMP	100	Target bed temp
WAIT	30s	Time between measurements
TOL	0.004	Stability threshold (mm)
TREND_TOL	0.001	Trend flatness threshold
REQUIRED	3	Stable cycles required

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▶️ Usage

Run manually in terminal:

VERIFY_BED_STABILITY_MULTI BED_TEMP=100 WAIT=30

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🧪 Integration Example (START_PRINT)

recommended usage pattern, do not copy it into your START_PRINT:

[gcode_macro START_PRINT]
gcode:
    {% set BED_TEMP = params.BED_TEMP|default(100) %}
    {% set EXTRUDER_TEMP = params.EXTRUDER_TEMP|default(220) %}

    # Start heating (non-blocking)
    M140 S{BED_TEMP}
    M104 S{EXTRUDER_TEMP}

    HEAT_SOAK

    # Verify bed thermal stability
    VERIFY_BED_STABILITY_MULTI BED_TEMP={BED_TEMP}

    # Generate mesh AFTER stabilization
    BED_MESH_CALIBRATE

    # Final nozzle heat
    M109 S{EXTRUDER_TEMP}

    # Prime / prep
    G92 E0
    G1 Z5 F3000

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⚠️ Important Notes

• Requires a properly configured Eddy current probe
• PROBE must return consistent last_z_result
• Adjust probe margins to avoid clips / edges
• Increase WAIT for thicker beds (45–60s recommended)

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🧠 Design Philosophy

This implementation treats your printer as a feedback system, not a timer:

• Uses real measurements
• Reacts to physical behavior
• Stops when equilibrium is reached

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📜 License

MIT

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🙌 Credits

Built for advanced Klipper users pushing beyond traditional heat soak workflows.