Scout Alpha 1 Mechanical Baseline

The Scout Alpha 1 enclosure is the first purpose-built housing for the battery-powered detection node within the Wildlife Monitoring Platform.

This document establishes the initial mechanical design specification before detailed CAD modeling begins. It defines the selected hardware, enclosure architecture, component layout, and packaging constraints that will guide development through the first generation of prototypes.

Rather than attempting to optimize every dimension from the beginning, this specification focuses on creating a practical, serviceable enclosure that provides a solid foundation for future revisions as real-world testing begins.

This document should be treated as the initial mechanical specification for Scout Alpha 1. Dimensions and layouts will continue to be refined as purchased components are measured, prototypes are assembled, and testing identifies opportunities for improvement.

Design Objectives

Scout Alpha 1 is intended to become a compact, battery-powered wildlife detection node that can operate independently or as part of a larger system.

The enclosure should:

• Protect electronics from dust, rain, and normal outdoor exposure.
• Keep the camera’s optical path unobstructed.
• Expose the PIR sensor directly to the environment.
• Secure the battery safely without compressing the pouch.
• Allow straightforward assembly and servicing.
• Provide access to development interfaces during prototyping.
• Support repeatable tree or post mounting.
• Print reliably in PETG on a Bambu Lab A1 Mini.
• Leave room for future hardware improvements without redesigning the overall architecture.

The first enclosure prioritizes reliability, accessibility, and ease of iteration over achieving the smallest possible size.

Selected Hardware

These components establish the physical constraints that the enclosure is designed around.

Controller Board

The main controller is the Waveshare ESP32-S3 AIoT Camera Development Board.

Confirmed PCB Dimensions

Reserved CAD Envelope

• PCB: 37 × 37 × 10 mm
• Board and camera assembly: 37 × 37 × 20 mm
• Camera clearance envelope: 22 × 22 × 12 mm

The enclosure must also provide access to:

• USB-C connector
• microSD slot
• Power and Boot buttons
• Camera ribbon cable
• Onboard antenna clearance

Camera Module

Scout uses an OV5640 camera module.

Optical Specifications

The enclosure uses a replaceable clear polycarbonate window.

Current design target:

• Window: 26 × 26 × 2 mm
• Clear aperture: approximately 18 × 18 mm
• Replaceable retaining frame
• Matte black internal light path
• Small air gap between lens and window

The lens should never contact the protective window.

Motion Sensor

Scout uses an SR602 Mini PIR sensor for motion detection.

Design Envelope

• Body diameter: 15–16 mm
• Fresnel dome: 10–11 mm
• Installed depth: 20–25 mm
• Front opening: 11–12 mm
• Retaining recess: 15–17 mm

The sensor board remains inside the enclosure while the Fresnel dome passes through its own sealed opening.

A small integrated rain hood is planned to reduce direct weather exposure.

Battery

Scout uses a 3.7 V 3000 mAh lithium-polymer battery.

Battery Dimensions

• Length: 65 mm
• Width: 36 mm
• Thickness: 10 mm
• Weight: approximately 49 g

Battery Compartment

• Cavity: 67 × 38 × 12 mm
• Wire exit: 15 × 12 × 8 mm
• Connector pocket: 12 × 8 × 5 mm

The battery will be supported with thin foam and retained using a removable bracket or hook-and-loop strap.

No screws or printed features should create pressure points against the battery.

Connector pitch alone does not guarantee compatibility. Battery connector type and polarity should always be confirmed before connecting power.

Enclosure Dimensions

The initial enclosure is based on the following starting dimensions.

Estimated usable internal space:

• Height: 92–94 mm
• Width: 62–64 mm
• Depth: 35–39 mm

Component Layout

The current layout places components as follows:

• Camera centered near the top front.
• Controller board mounted directly behind the camera.
• PIR sensor positioned on the right service centerline.
• Status LED aligned with the PIR.
• Power switch mounted on the left side.
• Wiring routed primarily along the right side.
• Battery mounted horizontally in the lower section.
• Four integrated PCB standoffs.
• No bottom cable gland.

This arrangement simplifies wiring, protects the battery, and keeps the camera centered within the enclosure.

Internal Assembly

The enclosure is organized from front to back as follows:

1. Front enclosure wall
2. Camera and PIR mounting features
3. Camera and controller assembly
4. PCB standoffs
5. Battery
6. Foam support
7. Rear clearance
8. Rear gasket and service lid

The controller and battery may overlap in depth but should never contact one another.

PCB Mounting

The controller mounts using four integrated printed standoffs.

Starting Geometry

• Outside diameter: 7–8 mm
• Height: 4–6 mm
• Fastener: M3

Because the PCB mounting holes are larger than the screw diameter, the design should prevent lateral movement without stressing the board.

Rear Service Lid

The rear lid provides access for assembly and maintenance.

Starting Design

• Lid thickness: 4 mm
• Rain skirt: 6 mm
• Locating lip: 4 mm
• Sliding clearance: approximately 0.3–0.4 mm per side

Gasket

• 2 mm silicone
• 5–6 mm wide
• Continuous rectangular loop

Rear screws remain outside the sealed electronics compartment.

Camera Hood

The camera hood is designed as a separate replaceable component.

Starting dimensions:

• Width: 36–42 mm
• Projection: approximately 15 mm
• Thickness: 2.5–3 mm
• Side walls: 8–12 mm
• Downward angle: 5–10°

Its purpose is to:

• Reduce rain on the camera window
• Shade the lens
• Improve image quality
• Provide a controlled drip edge

Switch and Status LED

Current design envelopes:

Power Switch

• Opening: 13 × 6 mm
• Body: 18 × 8 × 8 mm
• Rear clearance: 12–15 mm

Status LED

• 3 mm indicator
• Sealed using a dedicated light pipe or transparent plug

Tree Mount

The mounting system remains separate from the rear service lid.

Backplate

The mount uses:

• Two 25 mm straps
• Printed guide rails
• Sliding attachment channels
• One lower retaining screw
• Rubber contact pads
• Drainage gap behind the enclosure

Separating the mounting system from the rear lid allows the enclosure to be serviced without removing it from the tree.

Measurements Still Required

Before detailed CAD can be finalized, the following measurements should be verified using the purchased hardware.

Controller

• PCB thickness
• Component height
• Camera carrier dimensions
• Lens diameter
• Lens protrusion
• Ribbon bend radius
• USB-C position
• microSD access
• Battery connector location
• Mounting hole diameter

PIR Sensor

• PCB diameter
• Dome diameter
• Dome height
• Installed height
• Pin spacing

Battery

• Actual dimensions
• Protection board thickness
• Wire exit
• Connector dimensions
• Connector polarity

Switch and LED

• Final body dimensions
• Mounting geometry
• Terminal clearance

Prototype Validation

Before moving beyond the initial enclosure design, the following should be completed:

1. Measure every purchased component.
2. Print calibration blocks for threaded inserts and pilot holes.
3. Validate PCB mounting.
4. Verify camera window clearance.
5. Test PIR fit.
6. Test gasket compression.
7. Verify sliding mount tolerances.
8. Assemble the first complete enclosure prototype.

Conclusion

This specification establishes the initial mechanical design for Scout Alpha 1 and provides the foundation for future enclosure development.

As prototype work progresses, measurements will become more accurate, clearances will be refined, and individual features will continue to evolve. The overall architecture, however, is intended to remain consistent throughout the Alpha 1 design process so improvements can be made without repeatedly redesigning the enclosure from scratch.