Building a MicroDuck, Part 2: The Hardware

Without parts there is nothing to build. In this part we work out what to order. You get one complete list, a short explanation of what every part does, and a checklist for when the boxes arrive.

No electronics experience? No problem. For every part I tell you what it does, so you know why you’re buying it.

What You’ll Do in This Part

1. Make a few decisions before you order.
2. Go through the parts list.
3. Gather the tools you need besides the parts.
4. Check your order when it arrives.

Before You Order

Decision 1: spare servos? The robot needs 14 Dynamixel servos. One spare is a cheap insurance against a broken motor. That’s my suggestion, not part of either guide.

Decision 2: the mouth servo. The design has room for a 15th servo for a mouth, but the walking model does not use it. I’ll skip it for now.

Decision 3: the print files. The tutorial says to print from a cad folder, but I can’t find one in the repository. I won’t order anything for the body until I know where the files come from. OpenELAB shows a matched set of printed parts.

Decision 4: the battery. The tutorial calls for a ready-made 6 V rechargeable pack with enough peak current, and says you don’t need a custom two-cell pack, a protection board or a special charger. It doesn’t name a product, so I’ll choose one and check its rating and connector before I buy.

The Parts List

The list is grouped by what the part is for. The quantities come from the tutorial’s bill of materials.

Brain and control

Motors

Power

Cables and connectors

Mechanical

Setup tools

Recommended extras from the tutorial: spare servos, a spare battery, spare wire and cables, JST-EH terminals, a crimping tool, and a multimeter for polarity and voltage.

Check Before You Buy

These are the mistakes that cost the most, so check them before you pay:

• Servos: the XL330-M288-T model. Other XL330 variants have different specs.
• Raspberry Pi: the Zero 2 W, not the older Zero. It may come without pin headers, and the IMU uses its I2C pins.
• IMU: a BNO080, BNO085 or BNO086 module, not a different sensor.
• Battery: 6 V, with enough peak current, and a connector that matches your switch and wiring.
• microSD card: buy from a seller you trust. Fake cards exist.
• Servo firmware: I haven’t found a firmware requirement in this build’s guides, so I’ll check the servos when they arrive.

What You Need Besides the Parts

• A 3D printer and PLA filament.
• A soldering iron, solder and some wire.
• A multimeter.
• A crimping tool for the connectors.
• A Bluetooth gamepad to steer the robot. The guide has a section on pairing one.
• A computer to flash the SD card and connect to the Pi.
• A 2.4 GHz Wi-Fi network. The Pi Zero 2 W doesn’t do 5 GHz.

The Servo IDs, in Advance

Every servo needs its own ID before it goes into the robot. The software expects this mapping:

The recommended servo settings are protocol 2.0, 1 Mbps, return delay time 0, and PWM slope 255. We do this in Part 4.

When the Boxes Arrive

Check everything before you start building. A wrong part now is easier to fix than a wrong part halfway through.

1. Count the servos. 14 XL330-M288-T, plus any spare.
   Bad result: the number is off. Contact the shop now.
2. Check the labels on the servos. They must be the M288-T model.
3. Check the Raspberry Pi and the IMU. A Zero 2 W, and a BNO08x module.
4. Check the battery. Undamaged, 6 V, and the right connector.
5. Tick off the list. Everything is there and you noted what you paid.

If It Didn’t Work

• A part is out of stock. Look for the same part elsewhere and check the exact model before you buy.
• You can’t find the print files. Look at the OpenELAB guide and its links first, and ask the author before printing something that may not match.
• You’re unsure about the battery. Ask someone who knows lithium cells before you order. This is the step where mistakes matter most.

What You Have Now

A complete parts list, a set of decisions, and a checklist for when it arrives. Next up: finding the print files and printing a test piece, so I know the parts fit before I print everything.

If you know where the print files are, or a battery that works well, tell me through the contact page.

Words Explained

• XL330-M288-T: the exact model of Dynamixel servo used here.
• OpenRB-150: a small controller board that talks to the servos.
• IMU: a motion sensor that measures tilt and movement.
• I2C: a two-wire way for chips to talk to each other.
• Servo ID: the number that tells the controller which servo is which.
• U2D2: a small adapter for setting up Dynamixel servos from a computer.
• PLA: a common, stiff 3D printing plastic.
• Shim: a thin washer that lets a joint turn smoothly.

Conclusion: Time to Shop

One list, a few open questions, and a clear idea of what every part is for. Order, wait, check, and then we start printing.

Small duck, big steps. Happy hacking!