G1OS installation

Full procedure to flash G1OS (the Mainsail-based operating system) onto the Raspberry Pi 4 SD card inside the G1 printer. Required when reinstalling the OS or replacing the SD card.

When to do it

First-time setup of a new machine
OS is corrupted and the printer does not boot
Replacing the SD card

Prerequisites

Tools: hex screwdriver (to open electronics box), SD card reader/adapter
Files: latest G1OS image from the G1OS GitHub repository (→ Releases) — the arm64 .img.xz for Raspberry Pi 4
Software: Raspberry Pi Imager installed on your computer
Machine state: powered off

Steps

1 — Remove the SD card from the printer

Turn off the printer
Open the electronics box: unscrew the two hex screws on the left side of the display
Locate the Raspberry Pi 4 behind the display
The SD card slot is behind the flat ribbon cable — gently remove the SD card

2 — Download the G1OS image

Go to the G1OS GitHub repository → Releases
Download the latest G1OS image — the arm64 .img.xz for Raspberry Pi 4 (e.g. ...-G1OS-raspberry_pi-arm64-bookworm-X.X.X.img.xz)

3 — Prepare the image file

Extract the downloaded .img.xz archive to obtain a .img file

4 — Flash the SD card with Raspberry Pi Imager

Insert the SD card into your computer
Open Raspberry Pi Imager
Choose Device → Select Raspberry Pi 4
Choose OS → Select Use custom → pick the .img file you extracted
Choose Storage → select your SD card
Click Next, then EDIT SETTINGS and configure:
- Hostname: G1OS → .local
- Username: pi
- Password: raspberry
- Go to Services tab → enable SSH → Use password authentication
Click Save, then confirm YES to apply OS customisation settings
Confirm to start flashing — wait for “Write Successful”

5 — Reinstall the SD card

Safely remove the SD card from your computer
Insert it back into the Raspberry Pi in the G1 printer
Reassemble and close the electronics box
Power on the printer

6 — Connect and configure G1OS

Connect the printer to your Wi-Fi from the Klipper menu on the display
From your PC, open a browser and go to g1os.local

If the printer doesn’t connect via g1os.local, try restarting the router

Final verification

The G1OS Mainsail dashboard appears at http://g1os.local in your browser. The printer shows as connected and temperatures are visible.

Notes

After a fresh OS install, follow Migration to new Configurator to initialize the printer with your serial number
If the machine was previously configured, perform a Klipper firmware update after connecting
The SD card slot is tight and partially hidden by the ribbon cable — be gentle to avoid bending the connector