259 lines
No EOL
4.4 KiB
Markdown
259 lines
No EOL
4.4 KiB
Markdown
# sv06-belt-recovery-stress-tests
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Belt tension recovery and motion stability test models for bed-slinger 3D printers (e.g., SV06-class machines).
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---
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## Purpose
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These models are designed to help recover from situations where printer motion accuracy has been degraded, typically due to:
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* Adjusting belt tension without a reference baseline
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* Experiencing layer shifts during prints
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* Replacing belts or modifying mechanical components
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This project provides:
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* Parametric OpenSCAD models
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* A structured test procedure
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* Guidance for interpreting failure modes
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---
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## When To Use This
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Use these tests if you observe:
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* Sudden layer shifts (e.g., 3-5 mm offsets)
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* Inconsistent dimensional accuracy
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* Audible belt skipping or motor stutter
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* After adjusting belt tensioners
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Here's an example of a case for a hand held radio where the top suddendly shift at the 20mm height.
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---
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## Models Included
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### 1. Cube (Baseline Test)
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* Dimensions: 40 × 40 × 40 mm
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* Purpose:
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* Verify basic printer stability
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* Detect gross mechanical issues
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---
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### 2. Y-Bar (Axis Stress Test)
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* Dimensions: 20 × 150 × 50 mm
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* Purpose:
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* Stress the Y-axis (bed movement)
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* Detect belt slip under momentum and direction reversal
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**Important:**
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* Orient the 150 mm dimension front-to-back on the bed
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---
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### 3. Tower (Long-Duration Test)
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* Dimensions: 18 × 18 × 120 mm
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* Purpose:
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* Reveal issues that appear only over time
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* Detect cumulative drift, resonance, or late-stage layer shifts
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---
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## Print Procedure (Recommended Order)
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Run each model as a **separate print job**:
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1. **Cube**
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* Confirms system is not fundamentally broken
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2. **Y-Bar**
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* Directly tests axis tension and inertia behavior
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3. **Tower**
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* Tests stability over time and height
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---
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## Suggested Slicer Settings (Orca Slicer)
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### Cube
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* Layer height: 0.20 mm
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* Perimeters: 3
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* Infill: 20-25% (grid or gyroid)
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### Y-Bar
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* Layer height: 0.20 mm
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* Perimeters: 3
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* Infill: 15-25% (grid recommended)
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### Tower
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* Layer height: 0.20 mm
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* Perimeters: 3
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* Infill: 0-10%
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* Brim: optional (only if adhesion is an issue)
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See the settings folder for settings used in Orca Slicer.
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---
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## Belt Tension Guidance
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This project assumes GT2 belts (typical for most hobby printers).
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### Frequency Method (Recommended)
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Using a phone-based spectrum analyzer:
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* Target range: **90-110 Hz**
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* Reference: ~110 Hz ? ~2 lb tension (Voron baseline)
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Procedure:
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1. Move bed so belt span ~ 150 mm
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2. Pluck belt
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3. Measure frequency
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4. Adjust tensioner
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5. Repeat until stable
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### Notes
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* Too loose:
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* Low frequency (<70 Hz)
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* Layer shifts likely
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* Too tight:
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* High frequency (>120-130 Hz)
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* Motor strain, possible missed steps
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---
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## Interpreting Results
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### Good Result
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* Clean vertical alignment
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* No sudden offsets
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* Consistent layer stacking
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---
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### Failure Modes
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#### Sudden Layer Shift
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* Cause:
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* Belt too loose
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* Pulley slipping
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* Action:
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* Increase tension slightly
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* Check motor pulley set screws
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---
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#### Repeated Shift at Same Height
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* Cause:
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* Mechanical obstruction
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* Cable snag
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* Action:
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* Inspect motion path
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* Check wiring harness clearance
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---
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#### Gradual Lean / Drift
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* Cause:
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* Frame or axis alignment issue
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* Action:
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* Inspect rails, wheels, or rods
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---
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#### Ringing / Ghosting (No Shift)
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* Cause:
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* High acceleration
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* Action:
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* Reduce acceleration (not a belt issue)
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---
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## Notes on Methodology
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These tests intentionally:
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* Emphasize repeated motion in one axis
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* Increase inertial load with height
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* Create conditions where marginal tension fails visibly
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This approach isolates motion system issues rather than general print quality.
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---
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## OpenSCAD Usage
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Generate models:
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```bash
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openscad -D 'model="cube"' -o cube_$(date +%Y%m%d_%H%M).stl stress_test_models.scad
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openscad -D 'model="ybar"' -o ybar_$(date +%Y%m%d_%H%M).stl stress_test_models.scad
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openscad -D 'model="tower"' -o tower_$(date +%Y%m%d_%H%M).stl stress_test_models.scad
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```
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---
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## Provenance
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Generated with:
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* OpenSCAD
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* Orca Slicer (recommended)
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* Frequency-based belt tuning derived from:
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* Voron Design tuning methodology
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This project was developed with ChatGPT.
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---
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## License
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Recommend: MIT or CC-BY 4.0 for broad reuse.
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---
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## Contributing
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Improvements welcome:
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* Additional test geometries
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* Axis-specific stress models
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* Automated calibration workflows
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--- |