diff --git a/README.md b/README.md
index e8c80dd..11f69a6 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,259 @@
-# motion-diagnostics-suite
+# sv06-belt-recovery-stress-tests
 
-Parametric OpenSCAD models and procedures for diagnosing layer shifts, belt tension, and motion instability in FDM 3D printers.
\ No newline at end of file
+Belt tension recovery and motion stability test models for bed-slinger 3D printers (e.g., SV06-class machines).
+
+---
+![](img/DSC_5098.webp)
+## Purpose
+
+These models are designed to help recover from situations where printer motion accuracy has been degraded, typically due to:
+
+* Adjusting belt tension without a reference baseline
+* Experiencing layer shifts during prints
+* Replacing belts or modifying mechanical components
+
+This project provides:
+
+* Parametric OpenSCAD models
+* A structured test procedure
+* Guidance for interpreting failure modes
+
+---
+
+## When To Use This
+
+Use these tests if you observe:
+
+* Sudden layer shifts (e.g., 3-5 mm offsets)
+* Inconsistent dimensional accuracy
+* Audible belt skipping or motor stutter
+* After adjusting belt tensioners
+
+Here's an example of a case for a hand held radio where the top suddendly shift at the 20mm height.
+![](img/20260318_215156_Wed.png)
+---
+
+## Models Included
+
+### 1. Cube (Baseline Test)
+
+* Dimensions: 40 × 40 × 40 mm
+* Purpose:
+
+  * Verify basic printer stability
+  * Detect gross mechanical issues
+
+---
+
+### 2. Y-Bar (Axis Stress Test)
+
+* Dimensions: 20 × 150 × 50 mm
+* Purpose:
+
+  * Stress the Y-axis (bed movement)
+  * Detect belt slip under momentum and direction reversal
+
+**Important:**
+
+* Orient the 150 mm dimension front-to-back on the bed
+
+---
+
+### 3. Tower (Long-Duration Test)
+
+* Dimensions: 18 × 18 × 120 mm
+* Purpose:
+
+  * Reveal issues that appear only over time
+  * Detect cumulative drift, resonance, or late-stage layer shifts
+
+---
+
+## Print Procedure (Recommended Order)
+
+Run each model as a **separate print job**:
+
+1. **Cube**
+
+   * Confirms system is not fundamentally broken
+
+2. **Y-Bar**
+
+   * Directly tests axis tension and inertia behavior
+
+3. **Tower**
+
+   * Tests stability over time and height
+
+---
+
+## Suggested Slicer Settings (Orca Slicer)
+
+### Cube
+
+* Layer height: 0.20 mm
+* Perimeters: 3
+* Infill: 20-25% (grid or gyroid)
+
+### Y-Bar
+
+* Layer height: 0.20 mm
+* Perimeters: 3
+* Infill: 15-25% (grid recommended)
+
+### Tower
+
+* Layer height: 0.20 mm
+* Perimeters: 3
+* Infill: 0-10%
+* Brim: optional (only if adhesion is an issue)
+
+See the settings folder for settings used in Orca Slicer.
+
+---
+
+## Belt Tension Guidance
+
+This project assumes GT2 belts (typical for most hobby printers).
+
+### Frequency Method (Recommended)
+
+Using a phone-based spectrum analyzer:
+
+* Target range: **90-110 Hz**
+* Reference: ~110 Hz ? ~2 lb tension (Voron baseline)
+
+Procedure:
+
+1. Move bed so belt span ~ 150 mm
+2. Pluck belt
+3. Measure frequency
+4. Adjust tensioner
+5. Repeat until stable
+
+### Notes
+
+* Too loose:
+
+  * Low frequency (<70 Hz)
+  * Layer shifts likely
+
+* Too tight:
+
+  * High frequency (>120-130 Hz)
+  * Motor strain, possible missed steps
+
+---
+
+## Interpreting Results
+
+### Good Result
+
+* Clean vertical alignment
+* No sudden offsets
+* Consistent layer stacking
+
+---
+
+### Failure Modes
+
+#### Sudden Layer Shift
+
+* Cause:
+
+  * Belt too loose
+  * Pulley slipping
+* Action:
+
+  * Increase tension slightly
+  * Check motor pulley set screws
+
+---
+
+#### Repeated Shift at Same Height
+
+* Cause:
+
+  * Mechanical obstruction
+  * Cable snag
+* Action:
+
+  * Inspect motion path
+  * Check wiring harness clearance
+
+---
+
+#### Gradual Lean / Drift
+
+* Cause:
+
+  * Frame or axis alignment issue
+* Action:
+
+  * Inspect rails, wheels, or rods
+
+---
+
+#### Ringing / Ghosting (No Shift)
+
+* Cause:
+
+  * High acceleration
+* Action:
+
+  * Reduce acceleration (not a belt issue)
+
+---
+
+## Notes on Methodology
+
+These tests intentionally:
+
+* Emphasize repeated motion in one axis
+* Increase inertial load with height
+* Create conditions where marginal tension fails visibly
+
+This approach isolates motion system issues rather than general print quality.
+
+---
+
+## OpenSCAD Usage
+
+Generate models:
+
+```bash
+openscad -D 'model="cube"'  -o cube_$(date +%Y%m%d_%H%M).stl  stress_test_models.scad
+openscad -D 'model="ybar"'  -o ybar_$(date +%Y%m%d_%H%M).stl  stress_test_models.scad
+openscad -D 'model="tower"' -o tower_$(date +%Y%m%d_%H%M).stl stress_test_models.scad
+```
+
+---
+
+## Provenance
+
+Generated with:
+
+* OpenSCAD
+* Orca Slicer (recommended)
+* Frequency-based belt tuning derived from:
+
+  * Voron Design tuning methodology
+
+This project was developed with ChatGPT.
+---
+
+## License
+
+Recommend: MIT or CC-BY 4.0 for broad reuse.
+
+---
+
+## Contributing
+
+Improvements welcome:
+
+* Additional test geometries
+* Axis-specific stress models
+* Automated calibration workflows
+
+---
\ No newline at end of file
diff --git a/openscad/stress_test_models.scad b/openscad/stress_test_models.scad
index 6fed3be..95fb68c 100644
--- a/openscad/stress_test_models.scad
+++ b/openscad/stress_test_models.scad
@@ -147,8 +147,48 @@ module rounded_box_uncentered(x, y, z, r) {
                 square([x, y], center=false);
 }
 
-
 module place_top_label(txt, x, y, z, center_it=false) {
+
+    // --- parameters ---
+    margin = 2;  // mm clearance from edges
+
+    // usable space
+    usable_x = x - margin;
+    usable_y = y - margin;
+
+    // choose orientation: run along long axis
+    rotate_text = (y > x);
+
+    // limiting width after orientation
+    limit = rotate_text ? usable_y : usable_x;
+
+    // crude text width estimate factor (~0.6 * size * chars)
+    est_char_width = 1.0;
+    est_len = len(txt) * est_char_width;
+
+    // compute size that fits
+    auto_size = limit / est_len;
+
+    // clamp to your preferred max size
+    final_size = min(label_size, auto_size);
+
+    // placement
+    tx = center_it ? 0 : x/2;
+    ty = center_it ? 0 : y/2;
+    tz = center_it ? z/2 : z;
+
+    translate([tx, ty, tz - label_depth])
+        rotate([0, 0, rotate_text ? 90 : 0])
+            linear_extrude(height=label_depth + 0.02)
+                text(
+                    txt,
+                    size=final_size,
+                    font=label_font,
+                    halign="center",
+                    valign="center"
+                );
+}
+module place_top_labelOLD(txt, x, y, z, center_it=false) {
     tx = center_it ? 0 : x/2;
     ty = center_it ? 0 : y/2;
     tz = center_it ? z/2 : z;