EYEMECH ε3.2 Assembly Guide

NM Robotics

Fully 3D-printable animatronic eye mechanism compatible with hobby electronics and micro servos.

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Overview

The EYEMECH ε3.2 mechanism can be entirely 3D printed and built using common hobby electronics.

Recommended components and community:

• Website: https://nmrobots.com/
• Discord: https://discord.gg/qXKNRgHKNB

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Parts, Tools & Requirements

Skill Level

Suitable for experienced beginners in 3D printing and electronics.

• Some dexterity required
• Support removal can be delicate

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Required Parts

Servos (6x Micro Servos)

Choose one:

• M0090 — Quiet, strong, sturdy - our new favourite and possibly our new standard in the future
• SG90 — Low cost, weaker/slower
• MG90s — Recommended balance of cost and power

Other similar-form servos may work but are not fully tested.

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Eyes (2x)

Choose one:

• Realistic Eyes
• Ultra Realistic Eyes
• DIY 3D printed eyes

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Controller

• 1x Eye Mechanism Controller Board
• Optional: 1x Handheld Controller Board

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Budget Alternative

Instead of the official board:

• Raspberry Pi Pico
• Breadboard
• Jumper wires
• Two-way switch

Note: Reliability may be reduced compared to the dedicated board.

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Tools

• Reliable 3D printer
• PLA filament (quality recommended)
• Scraper tool (for supports)
• Data-capable USB cable (not power-only)

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Selecting a Design

Two variants are available:

Factor	ε2 (Snap-fit)	ε3.2-PIP (Print-in-place)
Ease of Printing	⭐⭐⭐⭐	⭐⭐⭐
Post-processing	⭐⭐⭐⭐⭐	⭐⭐⭐
Ease of Assembly	⭐⭐	⭐⭐⭐⭐⭐
Accuracy	⭐⭐⭐⭐	⭐⭐⭐

Recommendation

If unsure:

• Use MG90s servos
• Choose ε3.2-PIP (Print-in-place)

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Servo Fit Test

Due to servo manufacturing variations:

1. Print the servo fitting block
2. Test which hole fits best
3. Select the matching lettered parts
4. Fit should be tight but not damaging

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Manufacture

All parts fit on a Bambu X-1 Carbon or P1 series printer.

Print Settings

• PLA recommended
• 0.2mm layer height
• Organic/tree supports recommended
• Ensure pivot rods/rings are parallel to bed
• For ε2: pivot openings facing down

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Post-Processing

• Remove supports carefully
• Avoid stressing delicate pivot features

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Assembly (ε3.2-PIP)

Video guide:
https://youtu.be/MeHLouL9ltw

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Assembly Overview

1. Insert servo into X-Axis Subassembly A
2. Clip Y-Axis Subassembly on top
3. Attach central pivot holders
4. Attach X-Axis Subassembly B (leave loose)
5. Snap assembly into main base
6. Attach eyes
7. Attach eyelids (top = short levers, bottom = long)
8. Snap outer eyelid pivots underneath base
9. Install remaining 5 servos
10. Secure with retainers
11. Insert PCB holders
12. Snap PCB into place

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Wiring & Code

Compatible with:

• NM Robotics β1.2 EyeMech Board
• Raspberry Pi Pico

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Firmware Installation

1. Download MicroPython firmware:
   https://micropython.org/download/RPI_PICO/

2. Install Thonny IDE:
   https://thonny.org/

3. Hold BOOT while plugging Pico into PC

4. Copy .uf2 firmware to device

Official guide:
https://www.raspberrypi.com/documentation/microcontrollers/micropython.html

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Required Libraries

Install via Thonny:

• picozero
• micropython-servo

Steps:

1. Select interpreter
2. Tools → Manage Packages
3. Install from local file

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Uploading Code

1. Open EyeMechEpsilon3.py
2. Run to confirm no errors
3. Save as main.py on Pico

This enables auto-run on boot.

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Servo Wiring (Without Official Board)

Pico Pin	Connect To
VBUS (5V)	Servo Power (Red)
GND	Servo GND (Black/Brown)
GPIO10	Left/Right
GPIO11	Up/Down
GPIO12	Top Left
GPIO13	Bottom Left
GPIO14	Top Right
GPIO15	Bottom Right
GPIO7	Mode Switch → GND

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Calibration

1. Set board to Hold
2. Power on
3. Eyes centered and forward
4. Lids closed meeting in middle
5. Secure servo horns

Up/Down servo may need temporary removal for access.

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Operation

• Move Mode → Random movement
• Controller Connected → Manual mode
  • Joystick = Eye direction
  • Button = Blink
  • Rear slider = Default eyelid openness

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Support

• https://nmrobots.com/
• https://discord.gg/qXKNRgHKNB