BLOCK #011

Building a Bitaxe from Scratch

10 min read

Building a Bitaxe from scratch is one of the most technically satisfying projects in the Bitcoin open-source world. It's also genuinely difficult. This guide is for makers, electronics enthusiasts, and people who want to understand their hardware at the component level.

Honest difficulty rating: Advanced This requires soldering BGA/QFN components at fine pitch, working with lead-free solder, and familiarity with ESP32 firmware flashing. If you haven't soldered SMD components before, a pre-built Bitaxe is strongly recommended. That said; this is exactly the kind of project the open-source community exists for.

Why Build Instead of Buy?

You probably won't save money building vs buying a pre-assembled Bitaxe. The value is different:

  • Deep understanding of the hardware you're running
  • Contributing to the open-source ecosystem
  • The satisfaction of mining Bitcoin on something you built
  • Access to the bleeding edge, new variants often appear as DIY builds before commercial availability
  • Repair capability, if something fails, you know what everything does

Hardware Design Files

PCB files are in KiCad format. Export Gerber files and submit to a PCB manufacturer. JLCPCB and PCBWay are popular choices. JLCPCB offers SMT assembly that can handle passive components and the ESP32 module.

Sourcing the ASIC Chip

The mining chip is the hardest component to source. Bitmain's chips (BM1397, BM1366, BM1368, BM1370) aren't sold directly. Sources:

  • AliExpress: BM1366/BM1368 chips are available from several sellers. Quality varies, buy from sellers with strong reviews and prior Bitaxe builder feedback in the OSMU Discord.
  • OSMU Discord marketplace: Community members sometimes sell individual chips or chip lots.
  • Salvage from old miners: Chips from dead Antminers can be harvested with hot air rework, though this carries risk.

Verify chip authenticity, counterfeit and remarked chips exist. The community Discord is the best resource for identifying reliable chip sources.

Tools Required

  • Soldering iron: Temperature-controlled, fine tip (0.2–0.4mm). Hakko FX-888D or similar quality.
  • Hot air station: Essential for the ASIC chip. Quick 861DW or similar. Precise temperature control required.
  • Flux: No-clean paste flux, critical for all fine-pitch work.
  • Solder: 0.3–0.5mm. Leaded (63/37 Sn/Pb) is easier to work with for beginners.
  • Multimeter: For continuity testing and power rail verification before first power-on.
  • Microscope or loupe: Strongly recommended for inspecting fine-pitch joints. A USB digital microscope (~$40) is sufficient.
  • Solder wick and IPA + brush: For fixing mistakes and cleaning flux residue.

Assembly Overview

1. Passive Components

Start with resistors, capacitors, and inductors (0402/0603 SMD packages). Straightforward with a fine tip and flux. Reference the BOM and silk screen markings.

2. ICs and Connectors

USB-C connector, voltage regulators, and smaller ICs come next. The voltage regulator is critical: a mis-soldered power rail can destroy the ASIC chip. Test with a multimeter before proceeding.

3. The ESP32 Module

The ESP32-S3 module is castellated, soldered via edge pads. Use flux and a drag-soldering technique. Inspect under magnification for bridges after soldering.

4. The ASIC Chip

The most technically demanding step. Apply paste flux to the pads. Place the chip using the PCB silkscreen for alignment. Use hot air (typically 350°C, 40–60 L/min depending on your station) in slow circular passes from the outside in. Watch for the chip to settle as solder reflows. Do not rush this step.

5. Display and Fan Connector

Header pins, OLED display, and fan connector: the easiest parts of the board.

Flashing AxeOS Firmware

  1. Download the latest AxeOS release from github.com/skot/ESP-Miner/releases
  2. Connect the Bitaxe to your computer via USB-C
  3. Use the AxeOS web flasher (available at the GitHub page) or esptool.py from the command line
  4. Flash the provided .bin file to the correct address (see the GitHub release notes for the exact command)
  5. After flashing, the Bitaxe should boot into the AxeOS setup screen

Community Resources

  • OSMU Discord: The primary community hub, channels for hardware questions, sourcing chips, and build troubleshooting. Find the invite at the OSMU GitHub.
  • GitHub Issues: Bug reports and build questions for both hardware and firmware repos.
  • Reddit: r/BitaxeMiner has build photos, questions, and community discussion.

Is It Worth It?

For most people, buying a pre-built Bitaxe is the better choice. It's cheaper once you factor in tools, time, and inevitable rework. Pre-built units are properly assembled, tested, and supported.

For the people this guide is written for, makers who want to understand what's inside the machine, contribute to the open-source hardware ecosystem, or simply build something with their hands; it's absolutely worth it. You'll understand Bitcoin mining at a level most people never reach, on hardware you built yourself. Welcome to the open-source mining community.