sl-mechanical
a0d0c1211b
Add csi_rain_shield.scad with parametric visor-style protective shields for all 4 Raspberry Pi CSI cameras (IMX219). Features: - Visor-style overhang (32mm forward extension) shields lens from rain and direct sunlight - Drip edge prevents water from trickling back onto PCB - Snap-fit tabs (4 per shield, no fasteners required) - Ventilation slots prevent moisture condensation - Optional transparent polycarbonate lens cover insert - Radially symmetric design fits all 4 cameras Includes comprehensive BOM with: - Print settings and material specifications - Assembly instructions for snap-fit installation - Maintenance and troubleshooting guide - Weather resistance performance notes - Design variants for different conditions - Post-print finishing recommendations Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
295 lines
11 KiB
Markdown
295 lines
11 KiB
Markdown
# CSI Camera Rain/Sun Shield — BOM + Assembly
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**Rev A — 2026-03-02 — sl-mechanical**
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---
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## System Overview
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Protective visor-style rain and sun shields for all 4 Raspberry Pi CSI cameras (IMX219) on SaltyBot's sensor head.
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| Feature | Spec |
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|---------|------|
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| Application | Protects IMX219 cameras from rain, dust, and direct sunlight |
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| Camera interface | Snap-fit to camera housing (32×32 mm PCB with 38×38 mm face plate) |
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| Material | PETG (printed) or polycarbonate (lens cover) |
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| Coverage | All 4 cameras (radial arms at 0°/90°/180°/270°) |
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| Visor overhang | 32 mm forward extension |
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| Installation | Tool-free snap-fit (no fasteners required) |
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| Optional | Clear polycarbonate lens cover insert |
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---
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## Design Features
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- **Visor-style overhang:** 32 mm forward extension shields lens from rain and sun glare
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- **Drip edge:** Curved bottom lip (3 mm radius) prevents water from running back onto PCB
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- **Snap-fit tabs:** 4 flexible tabs clip into grooves on camera housing sides (no fasteners)
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- **Ventilation slots:** 3 vent slots per side prevent moisture condensation inside shield
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- **Lens cover groove:** Optional slot accepts removable 2.0 mm clear polycarbonate sheet
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- **Minimal weight:** ~8–10 g per shield (4 shields ≈ 32–40 g)
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- **No supports needed:** Flat-print orientation; minimal bridging
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---
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## Part A — Printed Shields
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### Single Shield Unit (csi_rain_shield.scad, RENDER="shield")
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**Purpose:** Protective visor for one CSI camera lens; clips onto camera housing.
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| Parameter | Value | Notes |
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|-----------|-------|-------|
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| Qty | 4 | One per camera (front, back, left, right) |
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| Material | PETG | 4 perimeters, 25% infill (speed-optimized) |
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| Print size | ~45 × 55 × 8 mm | Flat-face-down orientation |
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| Print time | ~25–35 min per shield | Total ~2 hours for all 4 |
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| Support | Minimal | Small bridging over drip edge only |
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| Wall thickness | 3 mm nominal | Adequate for snap-tab rigidity |
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**Key features:**
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- Curved top surface sheds water outward
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- 4 snap-fit tabs (one per side) with 0.4 mm clearance for easy on/off
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- Vent slots (3 on left, 3 on right) for air circulation
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- Integrated groove for optional lens cover
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- Drip edge prevents water from trickling back
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**Post-print finishing:**
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- Remove minimal support (drip edge underside)
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- Smooth any rough edges with 220-grit sandpaper
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- Test snap-tabs fit snugly (should click into place with light pressure)
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- Verify vent slots are open (clear with compressed air if needed)
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---
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## Part B — Optional Lens Cover
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### Clear Polycarbonate Insert (csi_rain_shield.scad, RENDER="lens_cover")
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**Purpose:** Optional removable transparent lens cover; protects optics while allowing light transmission.
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| Parameter | Value | Notes |
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|-----------|-------|-------|
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| Qty | 4 | One per camera (optional) |
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| Material | Polycarbonate sheet, clear | 2.0 mm thickness; cut from larger stock |
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| Size | ~44 × 44 mm (with flanges) | Trimmed to fit shield groove |
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| Optical quality | >90% transmission | Standard transparency grade; no special optics required |
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| Source | Cut from 2.0 mm clear polycarbonate sheet | Order stock, cut to size, sand edges smooth |
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**Installation:**
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1. Measure shield opening: approx. 38×38 mm (camera face size)
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2. Cut polycarbonate sheet to ~44×44 mm (includes 3 mm flange on each side)
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3. Sand edges smooth with 220+ grit (prevent scratching during insertion)
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4. Slide into groove on shield front (flanges grip in shield channels)
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5. Can be removed/cleaned without tools
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**Note:** Lens cover is **optional** — shields work fine without it. Use for:
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- Extreme weather (heavy rain, salt spray)
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- Coastal/sandy environments (dust protection)
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- High-temperature environments (reduces direct solar heating on sensor)
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---
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## Assembly Instructions
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### Installation on Camera Housing
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1. **Prepare shield:** Remove any support material; verify snap-tabs are flexible.
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2. **Position shield:** Orient visor away from camera (forward overhang extends away).
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3. **Align tabs:** Match snap-tab positions with grooves on camera housing sides.
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4. **Apply light pressure:** Snap shield onto housing with gentle thumb pressure.
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- You should hear/feel a "click" as each tab engages.
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- All 4 tabs should seat simultaneously (indicate correct orientation).
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5. **Verify fit:** Tug gently on shield — it should not move relative to housing.
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### Installation of Lens Cover (Optional)
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1. **Prepare cover:** Sand edges smooth; verify 44×44 mm dimension.
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2. **Align flanges:** Position cover so flanges align with groove channels on shield.
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3. **Slide into groove:** Insert cover from front, sliding flanges into shield grooves.
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4. **Check seating:** Cover should sit flush with shield front (no gaps).
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5. **Removal:** Gently pry from one corner to remove for cleaning.
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### Removal (For Cleaning/Replacement)
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1. **Lens cover:** Pop out with fingernail or plastic lever (takes 10 seconds).
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2. **Shield:** Flex one snap-tab up slightly while pulling shield forward.
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- Repeat on opposite side if needed.
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- Once one tab releases, shield pulls free easily.
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3. **Clean:** Wipe interior with dry cloth; use lens cleaner on polycarbonate if needed.
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4. **Reinstall:** Reverse steps above.
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---
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## Fastener List
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| # | Item | Qty | Notes |
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|---|------|-----|-------|
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| 1 | Printed shield (PETG) | 4 | See Part A specs above |
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| 2 | Polycarbonate lens cover | 4 | Optional; see Part B above |
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| – | **No fasteners required** | — | Shields attach via snap-fit tabs only |
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---
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## Mounting Configuration
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All 4 shields mount to radial arms of sensor_head.scad camera arms:
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```
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Top-down view (looking down at sensor head):
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Camera 1 (0°, front)
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▲
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│
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Shield │ Shield
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(270°) │ (90°)
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◄────-●─────►
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│
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│
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Camera 3 (180°, back)
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▼
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Each camera has a 32×32 mm PCB with 38×38 mm face plate.
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All 4 shields use identical design (radially symmetric).
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```
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---
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## Print Settings (Recommended)
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| Parameter | Value | Reason |
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|-----------|-------|--------|
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| **Nozzle temp** | 215–220 °C (PETG) | Prevent stringing; avoid over-heating |
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| **Bed temp** | 80 °C | Good adhesion for PETG |
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| **Print speed** | 40 mm/s | Normal speed; snapt-tabs need clean layers |
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| **Infill** | 25% | Sufficient for rigidity; saves weight & time |
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| **Perimeters** | 4 | Ensures solid snap-tabs |
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| **Supports** | Minimal (tree/linear) | Only under drip edge if needed |
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| **Orientation** | Flat-side-down | Visor face toward bed for best surface finish |
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| **Layer height** | 0.2 mm | Standard; 0.1 mm for improved surface finish |
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---
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## Mass Estimate
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| Component | Qty | Material | Est. mass |
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|-----------|-----|----------|-----------|
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| Rain shield (printed) | 4 | PETG | 8–10 g each (32–40 g total) |
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| Polycarbonate cover | 4 | PC sheet | 3–5 g each (12–20 g total, optional) |
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| **Subtotal (shields only)** | | | **32–40 g** |
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| **Total (with covers)** | | | **44–60 g** |
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**Impact on robot:** Negligible — <60 g added weight distributed symmetrically on sensor head.
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---
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## Weather Resistance
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| Condition | Protection | Notes |
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|-----------|-----------|-------|
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| **Light rain** | Excellent | Visor prevents direct water contact |
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| **Heavy rain** | Good | Drip edge minimizes runoff; vent slots allow drainage |
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| **Salt spray** | Good | PETG resists corrosion; rinsable with fresh water |
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| **Direct sunlight** | Excellent | Reduces lens heating; improves image contrast in bright conditions |
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| **Dust** | Very good | Visor blocks most airborne dust; lens cover optional for sandy environments |
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| **Snow/ice** | Fair | Shields prevent accumulation on lens; may require occasional wiping |
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---
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## Maintenance & Cleaning
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### Weekly (or after rain/dust storm)
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- **Wipe exterior:** Soft cloth, no cleaners (PETG safe with water only)
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- **Check vent slots:** Clear any debris with compressed air
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- **Verify snap-tabs:** Ensure shield hasn't loosened (retighten if needed)
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### Monthly (or as needed)
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- **Clean lens:** Remove polycarbonate cover; clean with lens cleaner + microfiber cloth
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- **Inspect for cracks:** Check snap-tabs and drip edge for damage
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- **Reattach cover:** Reinstall lens cover if removed
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### Seasonal (before extended operations)
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- **Deep clean:** Soak shields in warm soapy water; dry thoroughly
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- **Inspect material:** Check for UV degradation (yellowing, brittleness)
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- **Test fit:** Verify snap-tabs still grip firmly; replace if worn
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---
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## Troubleshooting
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| Issue | Cause | Solution |
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|-------|-------|----------|
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| Shield won't snap on | Tabs too tight | Sand snap-tabs lightly; verify groove alignment |
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| Shield rattles | Tabs too loose | Shim with thin tape; or reprint with tighter tolerance |
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| Water pooling inside | Vent slots blocked | Clear vents with compressed air |
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| Condensation on lens | Poor ventilation | Increase fan speed on sensor head or add desiccant packet |
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| Lens cover stuck | Flanges swollen | Let air-dry in sun for 1 hour; gently pry corner |
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| Drip edge cracked | Impact damage | Replace shield; or reinforce with epoxy + fiber tape |
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---
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## Design Variants
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### Variant 1: Enhanced Rain Protection (HEAVY WEATHER)
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- Extend visor overhang to 40 mm
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- Add full-width drip lip (vs. curved edge)
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- Thicken walls to 4 mm for durability
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- **Cost:** +10% weight, +5% print time
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### Variant 2: Minimal Sun Shield (LIGHTWEIGHT)
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- Reduce visor overhang to 20 mm
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- Thinner walls (2.5 mm)
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- Fewer vent slots (1 per side)
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- **Weight savings:** ~15%; best for dry climates
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### Variant 3: 360° Camera Protection (ADVANCED)
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- Add full-wrap shroud (not just visor)
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- Integrated housing covers (larger print)
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- Requires more support material
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- **Print time:** ~3 hours per shield
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---
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## Storage & Replacement
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**Shelf life:** PETG shields have indefinite shelf life if stored dry.
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**Replacement schedule:** Replace if:
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- Snap-tabs become loose or brittle
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- UV degradation visible (yellowing, embrittlement)
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- Cracks develop in visor
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- Polycarbonate cover becomes cloudy (clean first; replace if cloudiness persists)
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**Spares to keep:** 1–2 extra shields (in case of damage during field operations).
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---
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## Files & References
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| File | Purpose |
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|------|---------|
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| `csi_rain_shield.scad` | OpenSCAD parametric model (3 RENDER variants) |
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| `csi_rain_shield_BOM.md` | This document |
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| `imx219_mount.scad` | CSI camera housing reference (dependency) |
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| `sensor_head.scad` | Radial arm assembly reference |
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---
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## Assembly Checklist
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- [ ] Print all 4 shields (PETG, flat-face-down)
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- [ ] Remove support material (minimal)
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- [ ] Sand edges smooth (220 grit)
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- [ ] Test snap-tabs (should click into place with finger pressure)
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- [ ] Verify vent slots are open
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- [ ] *Optional:* Cut polycarbonate lens covers to size
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- [ ] *Optional:* Sand polycarbonate edges smooth
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- [ ] Mount shields on all 4 cameras (starting with front)
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- [ ] Verify all snap-tabs engaged
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- [ ] *Optional:* Install polycarbonate lens covers
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- [ ] Inspect for water shedding (test with water spray if available)
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- [ ] Label shields if needed (mark front/back camera positions)
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- [ ] Store spares in dry location
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