Building a micro-Duck, Part 5: Starting Over, the Right Way

In Part 1 I picked the XGO-Duck. In Part 4 I admitted I was lost among too many duck projects. This part ends that. I made a decision, and I’m starting from zero.

Forget the shopping list from Parts 1, 2 and 3. It belonged to a different robot. Everything from here on is new.

This post is written so that anyone can follow it. You don’t need to know anything about electronics, programming or 3D printing. If you can follow a recipe, you can follow this. Each step says what you need, what to do, what it should look like, and what to do if it doesn’t.

What are we building?

A small walking robot duck, about 25 cm tall. It’s a copy of the Microduck from Pollen Robotics. It can:

• walk, sit, and kick a ball,
• see through a camera,
• measure distance with a small 8 × 8 distance sensor,
• feel which way it is tilted (that’s what an “IMU” does),
• hear through a microphone and make sounds through a speaker,
• be steered with a game controller.

It has 15 small motors (called servos). Each one is a joint: hips, knees, ankles, neck, and beak.

The plan in four sentences

1. We 3D-print the body.
2. We order the electronics and motors.
3. We put it all together, plug in the cables and install the software.
4. We calibrate it (teach it where its “straight” is) and take the first steps.

Which duck, and why

There are many Microduck copies on the internet. After a lot of reading I chose kissqy/Microduck-kissqy. These are my reasons:

A fair warning. The original Pollen robot uses different motors (Dynamixel XL330). This copy uses a cheaper motor (Feetech HD-1910). So the walking software is the author’s own retrained version, not Pollen’s. That is the biggest risk in this project, and I’ll tell you honestly if it doesn’t work.

A note on licenses. The author’s circuit boards, console and walking models are free for personal, non-commercial use only. I’m building this as a hobby, and so should you.

Words you will meet

Read this list once. You can come back to it any time.

Safety first

These rules stay valid for the whole series.

1. The 3D printer gets hot. The nozzle is about 200 °C and the bed about 60 °C. Never touch them while it is on. Don’t leave the printer unattended for hours, especially early on. Put it on a hard, flat surface away from curtains and paper.
2. Batteries can start fires. Never short the contacts. Never charge on your bed or couch. Charge on a hard surface, in sight. If a battery swells, gets hot, or smells strange, stop using it.
3. Plus and minus matter. Connecting power the wrong way can destroy the electronics in a second. We always check twice before connecting a battery.
4. Disconnect before you build. Never plug or unplug cables while the battery is in.
5. Small parts. Screws and bearings are tiny. Keep them away from small children and pets.
6. Ventilation. Print in a room with fresh air.
7. Children. Young builders should build together with an adult, especially for printing, soldering and batteries.

What you need

Tools

• A 3D printer. I use a Creality Ender 3 V2 (bed 220 × 220 mm). Any similar printer works if its bed is about this size.
• A computer (Windows or Mac) with Wi-Fi.
• A small set of Phillips screwdrivers (small sizes).
• A wire stripper and side cutters.
• A multimeter (a cheap one is fine) to check that wires are connected the right way.
• A microSD card reader and a 32 GB microSD card.
• A smartphone.
• Tape, a small box for screws, and good light.

You do not need to solder. The circuit boards come ready-made.

The parts, in short

The full list with exact links, quantities and versions is in my order list. Here is what the groups are:

Where do I buy it?

Most parts are on AliExpress, and the table above links to them. Three parts are harder to find. Here is what I know, and what I do not know.

The boards only work if they are the author’s own open-source versions (HAT, IMU and HUB). Do not buy look-alikes.

Two important notes before you buy:

• Versions of the connectors. The HAT and IMU are sold in an older (EH2.5) and a newer (AMP2.0) connector version. The servos and cables here use AMP2.0 plugs. So you must order the AMP2.0 version of the HAT and IMU and confirm with the seller.
• The HUB and the battery contacts are not clearly for sale yet. The author’s pages say you must first check with him. So the first order step is a message, not a payment. See step 6.

Step by step: getting ready

We start with the parts that cost the most time, and the parts you can do right now: printing.

Step 1. Make a work area

You need: a table, a box, good light.

1. Clear a table. Put down a mat or cardboard.
2. Get a box with a lid for screws and small parts.
3. Make a folder on your computer called Microduck. Everything you download goes here.

It should look like: a tidy table and an empty folder.

Step 2. Download the print files

You need: a computer, the internet.

1. Open my print files page: https://github.com/AchimPieters/microduck-build
2. Click the green Code button, then Download ZIP.
3. Put the ZIP in your Microduck folder.
4. Open (unzip) it. Double-click it on a Mac, or right-click and choose Extract All on Windows. No extra program is needed.
5. Inside you will find:
   • 36 .stl files (the 3D parts),
   • one .3mf file (the author’s suggested layout on 5 plates).

It should look like: a folder with many .stl files in sub-folders, and one .3mf file.

Goes wrong? If the page says “404”, the files are not public yet. Try again later.

Downloaded files can be unsafe in general. This one is a plain archive of 3D models. Don’t run anything else from it. The models are the work of the original author; see the Sources.

Step 3. Install a slicer

The slicer turns the models into instructions for your printer. I use a free one.

1. Download UltiMaker Cura (free) from the official website, or PrusaSlicer.
2. Install it.
3. When it asks which printer you have, choose Creality Ender 3 V2. If you use another printer, choose that one.

It should look like: a blank grey 3D bed on your screen.

Step 4. Choose the colors

You can use any color. Pollen’s duck is mostly white with colored accents. The author uses orange, black, white and purple. Just pick PLA in the colors you like.

My suggestion for a look close to the original: white for the body, one accent color for beak and feet. This is my own taste, nothing more.

Step 5. A small test print first

Before the real parts, we print one small part to see that everything works.

You need: PLA, a clean bed.

1. Open Cura and click File, Open File(s). Pick one small part from your Microduck folder, for example neck-mount-left.stl from the folder print-files/stl-models/support-parts.
2. Choose these settings. They come from the author’s own print project, so they are a good start:

   Setting	Value
   Layer height	0.2 mm
   Infill (inside fill)	15 %
   Walls	2
   Nozzle	0.4 mm

   The usual PLA temperatures for most printers are about 200 °C nozzle and 60 °C bed. Check what is printed on your filament spool. This is general advice and not from the duck author.

3. Click Slice, then Save to Disk and save to the SD card of your printer. Put the card in the printer.
4. Start the print and watch the first layer. It should stick firmly to the bed, in neat straight lines.
5. Wait until it is done. Let it cool before removing it.

It should look like: a neat part, no loose strings, no gaps.

Goes wrong?

Step 6. Send the message to the seller (before you order)

The HUB and the battery contacts are the only parts for which I couldn’t find a clear buying link. I will not pay for anything until the seller answers.

How? Taobao sellers speak Chinese, so I use the Chinese text below. There are two ways. Either open the Taobao listing from “Where do I buy it?” (in section 4) and use its chat button (your browser can translate the page), or ask your forwarding service’s support to send the message for you. For the HUB you can also try the author’s WeChat code on the project page. This is general advice, I have not tried it yet.

Forwarding service, in short: you sign up, they give you an address of their warehouse in China, and you use that address as the delivery address at the seller. Later they send everything to your home. Compare a few services before you choose.

Chinese:

你好！我在制作 kissqy 的 FrankenDuck Microduck（飞特 HD1910 版）。请问：
1. 你的淘宝店是否出售 HUB（DXL_HUB_V2，带 1000µF 电容）？价格是多少？
2. 电池仓里 NP-F550 的电池触点／接线配件是否出售？具体型号是什么？
3. HAT、IMU 和 HUB 能否一起发到转运仓？
谢谢！

English:

Hello! I’m building your FrankenDuck Microduck (Feetech HD1910 version). Questions: 1) Does your Taobao shop sell the HUB (DXL_HUB_V2, with the 1000 µF capacitor)? 2) Do you sell the NP-F550 battery contacts / wiring parts for the battery holder? Which model? 3) Can the HAT, IMU and HUB ship together to a forwarding warehouse?

It should look like: a message sent, and then waiting for a reply. I’ll write the answer in the next part.

Step 7. Print the real parts

Now print the parts. The author arranged them on 5 plates (the .3mf file). The parts per plate are:

(This table comes from reading the author’s 3MF file. The part names are as in the file.)

Also print one battery holder. Pick one of these two files from the folder print-files/stl-models/body-parts:

• battery-holder_M2.5-screws_HUB-combo.stl: also holds the HUB board in place. This is my choice (if the seller sells the HUB).
• battery-holder_thick-clips.stl: the official style, with thicker clips.

Optional (skip for now): the roller-skate parts. Leave them out.

How to print each plate:

1. Open Cura. Import the STL files that belong to the plate (one plate at a time). Every part is small enough for the 220 × 220 mm bed. The largest is about 92 × 123 mm.
2. Arrange them on the bed so that none overlap.
3. Use the settings from step 5.
4. Slice, save and print.
5. After each plate, put the finished parts in a labeled bag: “Plate 1”, “Plate 2”, and so on.

It should look like: five labeled bags of parts and a battery holder.

Goes wrong? If a part fails halfway, throw it away and print it again. Never glue a failed print together. It must be strong, because a robot falls over.

Step 8. The soft feet (TPU)

TPU is rubbery. It is harder to print, especially on a printer like the Ender 3 V2, where the filament is pushed through a long thin tube (a “Bowden tube”). Soft filament can bend and jam in it. Take your time.

1. Resize the model first. The two sole files (left-sole-TPU.stl and right-sole-TPU.stl) are saved in meters. In Cura, scale them up by 1000. After scaling each sole should be about 41 × 54 × 13 mm. If it looks tiny, the scaling is missing. (I measured this in the files.)
2. Print slowly. TPU needs a low speed. A common starting point is about 20 mm/s. This is general advice, not from the duck author. Check the settings on your TPU spool.
3. Turn retraction off or very low. (Retraction is the setting where the printer pulls the filament back a bit; in Cura it is under “Travel”.) Otherwise the soft filament jams. This is also general advice.
4. Print the two soles.

It should look like: two soft, bendable soles that fit the foot parts.

Goes wrong? If the filament jams or bunches up near the extruder, stop. Slow down more and try again. If it keeps failing, try a smaller test piece.

Step 9. Sort and label

1. Make a list of all parts you printed.
2. Put each group in a bag with a label.
3. Write down any part that came out badly, so you can reprint it.
4. Take a photo of everything laid out. You’ll want it later.

[PHOTO: all printed parts laid out on the table]

What we do NOT know yet

Honest list of the open questions. I’ll answer each one in later parts:

• Will the seller sell the HUB and battery contacts? Until then I can’t finish the power part.
• Does the walking model work with my build? The author says yes. Nobody else has confirmed.
• Does my game controller pair with the author’s control program (the “console”)? The author uses a GameSir “Nova 2”. I plan to buy the GameSir Nova 2 Lite in Xbox mode. If that fails, an Xbox controller is the safe fallback, because Pollen’s own documentation lists it.
• Does import go smoothly? Some forwarding services handle magnets or batteries differently. That is why I’m buying the batteries locally.

What comes next

Nothing in those parts is written until I’ve actually done it. If the duck falls over, you’ll read that too.

Checklist for this part

• ☐ Work area ready
• ☐ Print files downloaded and unpacked
• ☐ Slicer installed
• ☐ Test print done
• ☐ Message to the seller sent
• ☐ Plates 1 to 4 printed in PLA
• ☐ Soles printed in TPU
• ☐ Battery holder printed
• ☐ Parts sorted and photographed

Sources

• Build guide: https://kissqy.github.io/Microduck-kissqy/build/
• Project: https://github.com/kissqy/Microduck-kissqy
• Print files (my copy): https://github.com/AchimPieters/microduck-build
• Original print set: https://github.com/kissqy/Microduck-kissqy/tree/main/hardware/3d-print-frankenduck
• Pollen Robotics Microduck: https://github.com/pollen-robotics/microduck
• Assembly notes (5 GHz Wi-Fi, capacitor): https://github.com/kissqy/Microduck-kissqy/blob/main/docs/ASSEMBLY-NOTES.en.md

Conclusion: Part 6 Is Unboxing

Part 6 starts when the parts arrive: we unpack, check everything, and set the ID number of each servo.

Previous: Part 4: Too Many Ducks

A clean start. Happy hacking!