AeroAlign/hardware/cad

SkyLogic AeroAlign - 3D Printable Parts

Status: active documentation for AeroAlign plus planned CoG fixtures
Design Tool: FreeCAD 0.20+
Export Format: STL

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Overview

This directory covers both halves of the project:

• AeroAlign IMU housings and clips
• future CoG scale fixtures and support cradles

All parts should stay printable on common 200mm-class FDM printers.

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Part List

Sensor Housing (Required)

1. sensor_housing_top.stl

   • Dimensions: 38mm × 28mm × 8mm
   • Features: Clip-on IMU holder, LED window, USB-C port access
   • Material: PLA or PETG
   • Infill: 20% cubic
   • Support: None required (designed for support-free printing)
   • Print time: ~45 minutes

2. sensor_housing_bottom.stl

   • Dimensions: 38mm × 28mm × 10mm
   • Features: Battery compartment (400mAh LiPo), 4× M2 screw holes
   • Material: PLA or PETG
   • Infill: 20% cubic
   • Support: Minimal (<10% volume)
   • Print time: ~1 hour

Control Surface Clips (Choose appropriate size)

3. clip_3mm.stl

   • For 3mm thick control surfaces (small foam ailerons)
   • Spring clip design, PETG recommended for flexibility
   • Rubber pad inserts: 6mm diameter × 1mm thick

4. clip_5mm.stl

   • For 5mm thick control surfaces (standard balsa elevators)
   • Most common size for RC models

5. clip_8mm.stl

   • For 8mm thick control surfaces (large rudders, thicker wings)
   • Reinforced jaw design

Multi-Sensor Expansion / Future AeroAlign

6. wing_surface_mount_adjustable.stl

   • 3-point contact clip for wing root attachment
   • Adjustable height: 10-20mm
   • Dimensions: 120mm × 80mm × 35mm
   • Rubber pad inserts: 6× pads (front, mid, rear)

7. wing_surface_mount_50mm.stl, wing_surface_mount_100mm.stl, wing_surface_mount_150mm.stl

   • Fixed-size wing clips for 50mm, 100mm, 150mm chord wings
   • Faster to print than adjustable version

8. control_surface_clip_springloaded_3mm.stl

   • Spring-loaded clip (PETG material required)
   • Grips trailing edge securely without adhesive

9. hinge_line_mount_universal.stl

   • L-shaped bracket for hinge line attachment
   • Measures differential directly at pivot point

10. magnetic_mount_base.stl

    • Self-adhesive metal plate (3M VHB backing)
    • Dimensions: 20mm × 10mm × 1mm
    • Pairs with sensor_housing_magnetic_top.stl

11. sensor_housing_magnetic_top.stl

    • Variant of sensor_housing_top.stl with magnet pockets
    • 2× N52 neodymium magnets (10mm diameter × 2mm thick)

CoG Scale Fixtures (Planned)

12. cog_baseplate.stl

    • Flat base aligning front and rear supports
    • Carries the support spacing reference

13. cog_support_front.stl

    • Front cradle above load cell #1
    • Should include anti-slip contact pad area

14. cog_support_rear.stl

    • Rear cradle above load cell #2
    • Matching geometry for repeatable support spacing

15. cog_hx711_mount.stl

    • Protected electronics bracket for HX711 boards
    • Cable strain relief recommended

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Print Settings

Recommended Settings (FDM)

Parameter	PLA (Housing)	PETG (Clips)	TPU (Optional)
Layer Height	0.2mm	0.2mm	0.25mm
Infill	20% cubic	30% grid	40% gyroid
Wall Count	3	4	3
Top/Bottom Layers	4	5	4
Print Speed	60mm/s	45mm/s	30mm/s
Nozzle Temp	205°C	235°C	215°C
Bed Temp	60°C	80°C	60°C
Support	None/Tree	Tree	None

Tolerances

• Screw holes: 2.2mm diameter (for M2 screws, accounts for ±0.2mm print variance)
• Clip jaw opening: ±0.3mm clearance for control surfaces
• Snap-fit features: 0.5mm interference for secure assembly

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Assembly Notes

Sensor Housing Assembly

1. Insert Electronics:

   • ESP32-C3 DevKit in top shell
   • MPU6050 IMU aligned with housing center
   • LiPo battery in bottom shell compartment

2. Close Housing:

   • Align top and bottom shells
   • Insert 4× M2×6mm screws through bottom, into top
   • Tighten until snug (do not overtighten, plastic may crack)

3. Attach Clip:

   • Choose appropriate clip size (3mm, 5mm, or 8mm)
   • Slide clip onto housing rails
   • Apply rubber pads to clip jaws (prevent surface scratches)

Magnetic Mount Assembly (Multi-Sensor)

1. Prepare Base Plate:

   • Clean model surface with isopropyl alcohol
   • Apply 3M VHB tape to magnetic_mount_base.stl
   • Press firmly onto wing/elevator (wait 24h for full adhesion)

2. Install Magnets:

   • Insert 2× N52 magnets into sensor_housing_magnetic_top.stl pockets
   • Ensure correct polarity (N-S attracts base plate magnets)
   • Secure with CA glue if loose

3. Attach Sensor:

   • Snap sensor housing onto magnetic base (2-second operation)
   • Magnets hold ~500g force (sufficient for workshop use)

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Design Files (Source)

FreeCAD Project Files (for customization):

• sensor_housing.FCStd - Parametric housing design
• clips_library.FCStd - Clip variants (3mm, 5mm, 8mm)
• wing_mounts.FCStd - Multi-sensor expansion mounts

To Export STL:

1. Open .FCStd file in FreeCAD
2. Select part in tree view
3. File → Export → Mesh Formats (.stl)
4. Settings: Deviation 0.1mm, Max mesh angle 20°

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Testing and Validation

Validation Tasks

• T058: Print sensor housing on Ender 3 (verify fit and tolerance)
• T059: Test print on Prusa Mini and Bambu Lab P1P (cross-printer compatibility)
• T060: Create assembly guide with photos
• T061: Document print settings for all STL files
• T062: Weigh assembled nodes (verify <25g per node)
• Validate CoG support rigidity under expected aircraft weights
• Validate repeatable support spacing for CoG calculation

Durability Testing

• T080: Drop test from 1 meter onto hard surface (10 times)
• T123: Test specialized mounts on RC model (foam wing, balsa surfaces)

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Material Costs

• PLA filament: ~20g per sensor housing = $0.40 @ $20/kg
• PETG filament: ~10g for 6 clips = $0.25 @ $25/kg
• Total material cost per system: $0.65 (negligible)

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Printer Compatibility

Tested on:

• Creality Ender 3 V2 ($200, 220mm build volume)
• Prusa Mini+ ($400, 180mm build volume)
• Bambu Lab P1P ($500, 256mm build volume)
• Anycubic Kobra ($250, 220mm build volume)

Minimum Requirements:

• Build volume: 200mm × 200mm × 200mm
• Layer height: 0.2mm capability
• Filament: PLA or PETG compatible

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Alternative: 3D Printing Services

If you don't own a 3D printer:

• 3D Hubs / Craftcloud: Upload STL, get quotes from local printers ($10-20 per set)
• Shapeways: Online 3D printing service (higher cost, premium materials)
• Local Makerspaces: Many libraries and hackerspaces offer 3D printing for members

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License

Hardware designs (STL files, FreeCAD sources) are licensed under: Creative Commons BY-SA 4.0

You are free to:

• Share: Copy and redistribute in any medium or format
• Adapt: Remix, transform, and build upon the material

Under the following terms:

• Attribution: Give appropriate credit to SkyLogic AeroAlign project
• ShareAlike: Distribute derivatives under same license

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Roadmap

Current: IMU housing and clips
Next: CoG baseplate and load-cell support fixtures
Later: integrated mixed-tool workshop kit

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SkyLogic AeroAlign - Precision Grounded.