saltylab-firmware/chassis/csi_rain_shield_BOM.md

CSI Camera Rain/Sun Shield — BOM + Assembly

Rev A — 2026-03-02 — sl-mechanical

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System Overview

Protective visor-style rain and sun shields for all 4 Raspberry Pi CSI cameras (IMX219) on SaltyBot's sensor head.

Feature	Spec
Application	Protects IMX219 cameras from rain, dust, and direct sunlight
Camera interface	Snap-fit to camera housing (32×32 mm PCB with 38×38 mm face plate)
Material	PETG (printed) or polycarbonate (lens cover)
Coverage	All 4 cameras (radial arms at 0°/90°/180°/270°)
Visor overhang	32 mm forward extension
Installation	Tool-free snap-fit (no fasteners required)
Optional	Clear polycarbonate lens cover insert

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Design Features

• Visor-style overhang: 32 mm forward extension shields lens from rain and sun glare
• Drip edge: Curved bottom lip (3 mm radius) prevents water from running back onto PCB
• Snap-fit tabs: 4 flexible tabs clip into grooves on camera housing sides (no fasteners)
• Ventilation slots: 3 vent slots per side prevent moisture condensation inside shield
• Lens cover groove: Optional slot accepts removable 2.0 mm clear polycarbonate sheet
• Minimal weight: ~8–10 g per shield (4 shields ≈ 32–40 g)
• No supports needed: Flat-print orientation; minimal bridging

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Part A — Printed Shields

Single Shield Unit (csi_rain_shield.scad, RENDER="shield")

Purpose: Protective visor for one CSI camera lens; clips onto camera housing.

Parameter	Value	Notes
Qty	4	One per camera (front, back, left, right)
Material	PETG	4 perimeters, 25% infill (speed-optimized)
Print size	~45 × 55 × 8 mm	Flat-face-down orientation
Print time	~25–35 min per shield	Total ~2 hours for all 4
Support	Minimal	Small bridging over drip edge only
Wall thickness	3 mm nominal	Adequate for snap-tab rigidity

Key features:

• Curved top surface sheds water outward
• 4 snap-fit tabs (one per side) with 0.4 mm clearance for easy on/off
• Vent slots (3 on left, 3 on right) for air circulation
• Integrated groove for optional lens cover
• Drip edge prevents water from trickling back

Post-print finishing:

• Remove minimal support (drip edge underside)
• Smooth any rough edges with 220-grit sandpaper
• Test snap-tabs fit snugly (should click into place with light pressure)
• Verify vent slots are open (clear with compressed air if needed)

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Part B — Optional Lens Cover

Clear Polycarbonate Insert (csi_rain_shield.scad, RENDER="lens_cover")

Purpose: Optional removable transparent lens cover; protects optics while allowing light transmission.

Parameter	Value	Notes
Qty	4	One per camera (optional)
Material	Polycarbonate sheet, clear	2.0 mm thickness; cut from larger stock
Size	~44 × 44 mm (with flanges)	Trimmed to fit shield groove
Optical quality	>90% transmission	Standard transparency grade; no special optics required
Source	Cut from 2.0 mm clear polycarbonate sheet	Order stock, cut to size, sand edges smooth

Installation:

1. Measure shield opening: approx. 38×38 mm (camera face size)
2. Cut polycarbonate sheet to ~44×44 mm (includes 3 mm flange on each side)
3. Sand edges smooth with 220+ grit (prevent scratching during insertion)
4. Slide into groove on shield front (flanges grip in shield channels)
5. Can be removed/cleaned without tools

Note: Lens cover is optional — shields work fine without it. Use for:

• Extreme weather (heavy rain, salt spray)
• Coastal/sandy environments (dust protection)
• High-temperature environments (reduces direct solar heating on sensor)

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Assembly Instructions

Installation on Camera Housing

1. Prepare shield: Remove any support material; verify snap-tabs are flexible.
2. Position shield: Orient visor away from camera (forward overhang extends away).
3. Align tabs: Match snap-tab positions with grooves on camera housing sides.
4. Apply light pressure: Snap shield onto housing with gentle thumb pressure.
   • You should hear/feel a "click" as each tab engages.
   • All 4 tabs should seat simultaneously (indicate correct orientation).
5. Verify fit: Tug gently on shield — it should not move relative to housing.

Installation of Lens Cover (Optional)

1. Prepare cover: Sand edges smooth; verify 44×44 mm dimension.
2. Align flanges: Position cover so flanges align with groove channels on shield.
3. Slide into groove: Insert cover from front, sliding flanges into shield grooves.
4. Check seating: Cover should sit flush with shield front (no gaps).
5. Removal: Gently pry from one corner to remove for cleaning.

Removal (For Cleaning/Replacement)

1. Lens cover: Pop out with fingernail or plastic lever (takes 10 seconds).
2. Shield: Flex one snap-tab up slightly while pulling shield forward.
   • Repeat on opposite side if needed.
   • Once one tab releases, shield pulls free easily.
3. Clean: Wipe interior with dry cloth; use lens cleaner on polycarbonate if needed.
4. Reinstall: Reverse steps above.

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Fastener List

#	Item	Qty	Notes
1	Printed shield (PETG)	4	See Part A specs above
2	Polycarbonate lens cover	4	Optional; see Part B above
–	No fasteners required	—	Shields attach via snap-fit tabs only

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Mounting Configuration

All 4 shields mount to radial arms of sensor_head.scad camera arms:

Top-down view (looking down at sensor head):

        Camera 1 (0°, front)
               ▲
               │
      Shield   │  Shield
        (270°) │    (90°)
         ◄────-●─────►
               │
               │
        Camera 3 (180°, back)
               ▼

Each camera has a 32×32 mm PCB with 38×38 mm face plate.
All 4 shields use identical design (radially symmetric).

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Print Settings (Recommended)

Parameter	Value	Reason
Nozzle temp	215–220 °C (PETG)	Prevent stringing; avoid over-heating
Bed temp	80 °C	Good adhesion for PETG
Print speed	40 mm/s	Normal speed; snapt-tabs need clean layers
Infill	25%	Sufficient for rigidity; saves weight & time
Perimeters	4	Ensures solid snap-tabs
Supports	Minimal (tree/linear)	Only under drip edge if needed
Orientation	Flat-side-down	Visor face toward bed for best surface finish
Layer height	0.2 mm	Standard; 0.1 mm for improved surface finish

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Mass Estimate

Component	Qty	Material	Est. mass
Rain shield (printed)	4	PETG	8–10 g each (32–40 g total)
Polycarbonate cover	4	PC sheet	3–5 g each (12–20 g total, optional)
Subtotal (shields only)			32–40 g
Total (with covers)			44–60 g

Impact on robot: Negligible — <60 g added weight distributed symmetrically on sensor head.

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Weather Resistance

Condition	Protection	Notes
Light rain	Excellent	Visor prevents direct water contact
Heavy rain	Good	Drip edge minimizes runoff; vent slots allow drainage
Salt spray	Good	PETG resists corrosion; rinsable with fresh water
Direct sunlight	Excellent	Reduces lens heating; improves image contrast in bright conditions
Dust	Very good	Visor blocks most airborne dust; lens cover optional for sandy environments
Snow/ice	Fair	Shields prevent accumulation on lens; may require occasional wiping

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Maintenance & Cleaning

Weekly (or after rain/dust storm)

• Wipe exterior: Soft cloth, no cleaners (PETG safe with water only)
• Check vent slots: Clear any debris with compressed air
• Verify snap-tabs: Ensure shield hasn't loosened (retighten if needed)

Monthly (or as needed)

• Clean lens: Remove polycarbonate cover; clean with lens cleaner + microfiber cloth
• Inspect for cracks: Check snap-tabs and drip edge for damage
• Reattach cover: Reinstall lens cover if removed

Seasonal (before extended operations)

• Deep clean: Soak shields in warm soapy water; dry thoroughly
• Inspect material: Check for UV degradation (yellowing, brittleness)
• Test fit: Verify snap-tabs still grip firmly; replace if worn

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Troubleshooting

Issue	Cause	Solution
Shield won't snap on	Tabs too tight	Sand snap-tabs lightly; verify groove alignment
Shield rattles	Tabs too loose	Shim with thin tape; or reprint with tighter tolerance
Water pooling inside	Vent slots blocked	Clear vents with compressed air
Condensation on lens	Poor ventilation	Increase fan speed on sensor head or add desiccant packet
Lens cover stuck	Flanges swollen	Let air-dry in sun for 1 hour; gently pry corner
Drip edge cracked	Impact damage	Replace shield; or reinforce with epoxy + fiber tape

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Design Variants

Variant 1: Enhanced Rain Protection (HEAVY WEATHER)

• Extend visor overhang to 40 mm
• Add full-width drip lip (vs. curved edge)
• Thicken walls to 4 mm for durability
• Cost: +10% weight, +5% print time

Variant 2: Minimal Sun Shield (LIGHTWEIGHT)

• Reduce visor overhang to 20 mm
• Thinner walls (2.5 mm)
• Fewer vent slots (1 per side)
• Weight savings: ~15%; best for dry climates

Variant 3: 360° Camera Protection (ADVANCED)

• Add full-wrap shroud (not just visor)
• Integrated housing covers (larger print)
• Requires more support material
• Print time: ~3 hours per shield

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Storage & Replacement

Shelf life: PETG shields have indefinite shelf life if stored dry.

Replacement schedule: Replace if:

• Snap-tabs become loose or brittle
• UV degradation visible (yellowing, embrittlement)
• Cracks develop in visor
• Polycarbonate cover becomes cloudy (clean first; replace if cloudiness persists)

Spares to keep: 1–2 extra shields (in case of damage during field operations).

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Files & References

File	Purpose
csi_rain_shield.scad	OpenSCAD parametric model (3 RENDER variants)
csi_rain_shield_BOM.md	This document
imx219_mount.scad	CSI camera housing reference (dependency)
sensor_head.scad	Radial arm assembly reference

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Assembly Checklist

• Print all 4 shields (PETG, flat-face-down)
• Remove support material (minimal)
• Sand edges smooth (220 grit)
• Test snap-tabs (should click into place with finger pressure)
• Verify vent slots are open
• Optional: Cut polycarbonate lens covers to size
• Optional: Sand polycarbonate edges smooth
• Mount shields on all 4 cameras (starting with front)
• Verify all snap-tabs engaged
• Optional: Install polycarbonate lens covers
• Inspect for water shedding (test with water spray if available)
• Label shields if needed (mark front/back camera positions)
• Store spares in dry location