What you're getting into
Astro Arrow is a project that doesn't require advanced knowledge of electronics or programming. You only need basic soldering skills and access to a 3D printer. The firmware is pre-built, the chassis is almost entirely 3D-printed, and every step has a detailed guide. If you can solder a header pin and follow a wiring diagram, you can build this.
I have created a detailed guide both in written and video formats to help you through each step of the build process. It will guide you through the entire process from start to finish.
Don't let the difficulty rating scare you. A 'intermediate difficulty' means you need patience and care - not expertise. The hardest part of this build is the assembly and solering. The calibration is done automatically by the device. The community is there if you get stuck. If you've got any questions, feel free to message me on discord - I will try my best to help you :)
What you need to know
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Basic solderingThrough-hole components only - header pins, terminals. No SMD, no fine-pitch chips. If you've soldered anything before, you're fine.
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Access to a 3D printerAny FDM printer with a 0.4 mm nozzle. PLA or PETG both work. Print tolerances are generous - no exotic settings required.
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Comfortable in a terminalYou'll run one or two commands to flash the firmware using PlatformIO. If you've ever used a command line, that's enough.
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Ability to read a wiring diagramWe provide a complete schematic. You just need to be able to match wire colours and labels to the right pins.
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Programming experience - not neededThe firmware is pre-compiled. You can use our web flashing tool to upload it to the device.
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PCB design or advanced electronics - not neededI've designed a custom PCB - you just need to insert the components and solder them in their marked spots.
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Astronomy knowledge - not neededThe device handles all the math. You pick a target and it points. The app teaches you the rest.
What you'll print
Around 80% of the Astro Arrow chassis is 3D-printed. The design is intentionally printer-friendly - no supports on critical surfaces, generous tolerances, and split into parts that fit on a standard 220 mm build plate.
All parts print in PLA or PETG at standard settings (0.2 mm layer height, 20% infill for structural parts, 4 perimeters). Total print time is roughly 4-6 hours, depending on your printer speed. Files are available in the GitHub repository.
Key printed components include the main turret body, azimuth ring base, elevation bracket, motor mounts, the 24-slot optical ring for homing, and the display/LED housing. The only non-printed mechanical parts are the motors, shafts, and hardware (screws and heat-set inserts).
What to order
All components are widely available from AliExpress, Amazon, or your preferred electronics supplier. Prices below are estimates - sourcing from AliExpress will be cheaper; buying locally or from Pimoroni/Adafruit will be faster but more expensive.
| Bought | Name | Qty | Cost (EUR / USD) | Buy |
|---|---|---|---|---|
| ESP8266 ESP-12E Module The main microcontroller. NodeMCU breakout recommended for easier flashing. | 1 | ~€4 / ~$4 | ||
| 5V DC Stepper Motor Model NFP-15BY-18 One for azimuth rotation, one for elevation tilt. | 2 | ~€7 / ~$8.5 | ||
| TMC2209 Stepper Motor Driver Controls each motor's step and direction signals. Buying one spare is still a good idea. | 2 | ~€6.3 / ~$7.4 | ||
| MCP23008 I2C GPIO Expander Provides extra I/O pins over I2C for motor control and display sync. | 1 | ~€2 / ~$2 | ||
| QMC5883P 3-Axis Magnetometer Compass module for heading detection. Lets the device compensate when moved or rotated. | 1 | ~€3 / ~$3 | ||
| 2.13" E-Ink Display Module 250×122 px, black and white. Displays status, tracking info, and calibration screens. | 1 | ~€11 / ~$12 | ||
| WS2812B RGB LED Strip A 5-LED segment is enough. Any WS2812B or NeoPixel-compatible strip works. | 1 | ~€3 / ~$3 | ||
| Optical Fork / Slot Sensor Used with the 3D-printed 24-slot ring for azimuth homing and calibration. | 1 | ~€2 / ~$2 | ||
| Dupont Jumper Wires + Header Pins For all point-to-point connections. Keep both M/F and M/M sets on hand. | Assorted | ~€3 / ~$3 | ||
| M3 Screws + Heat-Set Inserts M3×8 and M3×12 are the most common. Use brass inserts for the printed parts. | Assorted | ~€4 / ~$4 | ||
| PLA or PETG Filament (~200 g) Enough for all chassis parts. Any colour works; PETG is better for the motor mounts. | ~200 g | ~€6 / ~$6 | ||
| 5V / 12V Dual Power Supply The ESP8266 runs from regulated 5V while the motors run at 12V. A bench supply also works. | 1 | ~€7 / ~$8 | ||
| USB-to-Serial Adapter Needed for the initial firmware flash. CP2102 or CH340 boards are both fine. | 1 | ~€3 / ~$3 | ||
| Total Estimate | ~€63 / ~$68 | |||
Prices are rough estimates shown in both EUR and USD, rounded for readability, and they vary significantly by supplier and region. The buy buttons open vendor searches for each part so you can compare local options before ordering.
Tools you'll need
Nothing unusual. Most of this lives in a basic hobbyist toolkit.
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Soldering iron + solder Required.
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FDM 3D printer 0.4 mm nozzle is fine.
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Small Phillips screwdriver set Required.
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Wire strippers / side cutters Required.
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Heat gun or lighter For heat-set inserts.
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Computer with USB port For the firmware flash.
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Multimeter Recommended, but not required.
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Helping hands / PCB vice Nice to have.
The 8 steps
Each step has its own detailed page with photos, wiring diagrams, and troubleshooting notes. You don't need to do it all in one sitting - the device saves its state between sessions. The steps below link to the full guides as they're published.
Ready? Start with Step 1.
The first step is just printing parts. No soldering, no code - just downloading files and hitting print. A good way to get started while the rest of your components are in the mail.
Step 1: Print the PartsYou're not alone in this
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