System Image Flashing
System Image Flashing
System Introduction
FlyOS-Fast is a lightweight Linux system deeply customized for 3D printing, supporting all Mellow 3D printer mainboard platforms. Its features include:
- Fast boot speed, kernel optimization ensures Klipper's real-time performance
- File system optimization reduces the risk of boot failure caused by power loss
- KlipperScreen starts in 30 seconds
- Pre-installed services including Klipper, RRF, Mainsail, Fluidd, Moonraker, KlipperScreen, etc.
- Supports switching between Klipper and RRF systems
- Supports one-click switching between Mainsail and Fluidd online
- Supports USB printing, power failure recovery, serial screens
- Supports automatic firmware flashing on boot (for fly-c8, fly-geminiv3)
- Allows pre-setting default language and printer name for front-end UIs like Fluidd
For more OEM customization features (such as boot logo, preset configuration files, hiding Mainsail tabs, etc.), please contact us.
This system is a lightweight customized system. The built-in components and services such as klipper are not official original versions and do not support user modifications or upgrades.
- FLYOS-FAST system account is
root
, password ismellow
Preparation Before System Flashing
-
Prepare required equipment
- If using a TF card to boot the system, prepare the following equipment:
- Card reader
- One TF card with capacity between 16GB-128GB, transmission speed Class10 or above
- It is recommended to use TF cards from well-known brands such as
SanDisk
,Samsung
,Kioxia
, etc. DO NOT use unbranded TF cards! - A Windows system computer (Windows 7, 10, or 11 are all acceptable)
- If using a TF card to boot the system, prepare the following equipment:
-
Download FLY-H3 system image:
- The current FAST version is FlyOS-FAST-V1.2.47
- Please download the FLY-H3 image within the FlyOS-FAST-V1.2.47 folder
- Click the download link below
-
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tip- System file naming convention:
FlyOS-Fast-[chip series]-[version number].img
, for example: FlyOS-Fast-H3-v1.0.0.img - Windows system users download
.exe
files, which are self-extracting 7z compressed packages. After downloading, double-click to extract and obtain the.img
file (can only be decompressed on a Windows system) - For other systems like macOS and Linux, download the
.7z
file, which is a 7z compressed package. After downloading, use tools that support the 7z format to extract and obtain the.img
file - Due to the large system file size, other compression formats and source image downloads are not available for now
- This tutorial uses
.exe
and Google Drive as examples
- Access the cloud drive and click on FlyOS-FAST-V1.2.47
- Click on the image you need to download
- This tutorial requires downloading Fly_FAST-H3.exe
- Click "Download Anyway"
-
Extract the system image file to obtain the
.img
file.- Double-click or right-click to open FlyOS-Fast-H3.exe, after a few seconds a window like the following will pop up (if the system warns about security, click "More info" -> "Run")
- You can choose the extraction directory, then click the
Extract
button and wait for the extraction to complete.
- After extraction, a file named FlyOS-Fast-H3-vx.x.x.img will be generated in the extraction directory.
x.x.x
represents the system version number.
-
Install the device to be flashed on the computer
Flashing the System
-
Open Rufus, select the device. The displayed capacity should match the capacity of the inserted flash card.
-
Select
Boot selection
, by default chooseImage file
. -
To select the image file, click the
Select
button to the right ofBoot selection
, and choose the extracted.img
file. -
After selecting the image file,
Boot selection
will display the filename of the image. -
Click the
Start
button. If a window pops up prompting that the disk data needs to be cleared, clickOK
. -
Once flashing is complete, the computer will emit a prompt sound and the progress bar will show
Ready
. -
Do not rush to remove the flash card after flashing is complete.
-
Open File Explorer and check if there is a USB drive or removable disk named
FlyOS-Conf
. -
Open
FlyOS-Conf
. If the two files shown in the image below exist, the flashing was successful. -
Install the system card onto the motherboard.
Install System Card
- After flashing the system to the TF card, you need to connect the TF card to the back of the MINI PAD here; otherwise, the system cannot boot

Install Antenna
- Install the antenna properly
- Please note that the host computer does not support WiFi with Chinese names and does not support 5G WiFi
- The red arrow indicates the WiFi antenna interface
- The WiFi antenna port is
ipex1
- Please install the antenna; otherwise, poor signal may prevent connecting to the router

- After installing the system card, proceed to the next step and connect to the host via SSH
- Power the host computer.
At this point, your host computer is ready to boot up!!!
Please proceed to the next step: SSH Connect to Host
Modifying Other System Configuration Options
To modify other system configuration options, please refer to: Modifying System Configuration