Sunlu T3 Firmware Update ((new)) May 2026

Updating the firmware on a Sunlu T3 (also known as the "Terminator 3") is often a necessary step for enthusiasts because the stock firmware has several known limitations, including fan mapping errors and disabled PID tuning for the bed. The T3 is essentially a modified Ender 3 clone using a 32-bit board similar to the BTT SKR Mini E3 V2. Available Firmware Options

Depending on your comfort level with tinkering, you have three primary paths:

Official Sunlu Firmware: Official updates are hosted on the Sunlu Website or shared via their Official Facebook Page. Version 3.40 is a common stable target for official users.

Community Custom Firmware: Developers have released optimized Marlin versions that fix bugs found in the original code, such as incorrect extruder fan mapping where the fan only ran when motors were active rather than when the hotend was hot. You can find these on GitHub and Printables.

Self-Compiled Marlin: Since the T3 uses a standard architecture, you can compile your own firmware using the Marlin Configurations repository for the Sunlu T3, allowing for features like 5x5 grid bed leveling and higher hotend temperatures (up to 285°C) if you have an all-metal hotend. Installation Procedure

The T3 updates via a microSD card inserted directly into the motherboard slot at the front of the printer.

Format the Card: Use a microSD card formatted to FAT32 with an allocation unit size of 4096.

Prepare the File: Copy the .bin firmware file to the root directory of the card. Ensure it is the only .bin file present. Flash the Printer: Turn off the printer. Insert the microSD card. Power on the printer.

The screen will remain blank for several seconds while the light on the motherboard flashes. Once the main menu appears, the update is complete.

Post-Update Reset: It is highly recommended to select "Restore Defaults" and then "Store Settings" (EEPROM) after flashing to ensure old settings do not conflict with the new firmware. Key Improvements in Updated/Custom Firmware

Fixed Fan Control: Corrects the error where the hotend cooling fan fails to turn on during stationary heating.

PID Bed Tuning: Enables more stable bed temperatures, which Sunlu curiously left disabled in many stock versions.

Enhanced Leveling: Expands the Automatic Bed Leveling (ABL) to a more precise 5x5 grid.

Thermal Safety: Custom versions often include refined thermal runaway protection and higher temperature limits for upgraded hardware. Troubleshooting Common Issues sunlu 3d - Facebook

Sunlu T3 Firmware Update: A Comprehensive Guide

The Sunlu T3 is a popular 3D printer known for its high-quality prints, ease of use, and affordability. Like any other electronic device, the Sunlu T3 requires periodic firmware updates to ensure optimal performance, fix bugs, and add new features. In this write-up, we will guide you through the process of updating the firmware on your Sunlu T3 3D printer.

Why Update the Firmware?

Updating the firmware on your Sunlu T3 3D printer is essential to:

1. Fix bugs and issues: Firmware updates often include bug fixes and patches that resolve common issues, such as print quality problems, layer shifting, or heated bed malfunctions.
2. Improve performance: New firmware versions can optimize printer performance, resulting in faster print speeds, better temperature control, and more reliable prints.
3. Add new features: Firmware updates can introduce new features, such as support for new filament types, improved safety features, or enhanced user interface options.
4. Enhance security: Updating the firmware ensures that your printer is protected against known security vulnerabilities, safeguarding your device and data.

Preparation

Before updating the firmware on your Sunlu T3, make sure you: Sunlu T3 Firmware Update

1. Have a stable internet connection: Ensure that your computer or mobile device has a stable internet connection to download the firmware update.
2. Use a compatible computer or device: Use a computer or mobile device with a compatible operating system (Windows, macOS, or Linux) and a suitable USB port.
3. Connect the printer to the computer: Connect your Sunlu T3 3D printer to the computer using a USB cable.
4. Power on the printer: Turn on your Sunlu T3 3D printer and ensure that it is in a ready state.

Downloading the Firmware Update

To download the firmware update for your Sunlu T3:

1. Visit the official Sunlu website: Go to the official Sunlu website (www.sunlu.net) and navigate to the support or downloads section.
2. Select your printer model: Choose your Sunlu T3 model from the list of available printers.
3. Find the firmware update: Locate the firmware update section and find the latest version available for your printer.
4. Download the firmware file: Click on the firmware file to download it to your computer. The file should be in a format such as .bin or .hex.

Updating the Firmware

To update the firmware on your Sunlu T3:

1. Extract the firmware file: If the downloaded file is zipped or compressed, extract it to a folder on your computer.
2. Open the printer's control panel: Open the control panel on your Sunlu T3 3D printer. This can usually be done by navigating to the printer's menu and selecting "Control Panel" or "Settings."
3. Enable firmware update mode: In the control panel, navigate to the "Firmware Update" or "Update" section and enable firmware update mode. The printer may prompt you to confirm that you want to update the firmware.
4. Connect to the computer: Connect your Sunlu T3 to the computer using a USB cable.
5. Use a firmware update tool: Use a firmware update tool, such as the Sunlu-provided tool or a third-party tool like Arduino IDE, to upload the firmware file to your printer.

Using the Sunlu Firmware Update Tool

If you are using the Sunlu-provided firmware update tool:

1. Launch the tool: Launch the firmware update tool on your computer.
2. Select the firmware file: Browse to the location where you extracted the firmware file and select it.
3. Select the printer: Choose your Sunlu T3 3D printer from the list of available devices.
4. Start the update: Click "Update" or "Start" to begin the firmware update process.

Using Arduino IDE

If you are using Arduino IDE:

1. Install the Arduino IDE: Install the Arduino IDE on your computer if you haven't already.
2. Install the Sunlu T3 board: Install the Sunlu T3 board in the Arduino IDE.
3. Open the firmware file: Open the firmware file in Arduino IDE.
4. Select the board and port: Select the Sunlu T3 board and the corresponding port from the Tools menu.
5. Upload the firmware: Click the "Upload" button to upload the firmware to your printer.

Post-Update Checklist

After updating the firmware:

1. Verify the firmware version: Check the printer's control panel to ensure that the firmware version has been updated correctly.
2. Calibrate the printer: Perform a calibration routine to ensure that the printer is accurately configured.
3. Test print: Run a test print to verify that the printer is functioning correctly.

Troubleshooting

If you encounter any issues during the firmware update process:

1. Check the firmware file: Ensure that the firmware file is correct and not corrupted.
2. Check the USB connection: Verify that the USB connection is stable and not loose.
3. Restart the printer: Restart the printer and try the update process again.

To update the firmware on your Sunlu Terminator 3 (T3) , you typically need to

place a specifically named firmware file onto a MicroSD card and restart the printer

. The T3 uses a 32-bit controller board (similar to a BTT SKR Mini E3 V2 clone), which supports simple SD card flashing Update Instructions Prepare the SD Card

: Use a high-quality MicroSD card (ideally 8GB or 32GB). Format it to with a standard allocation unit size. Download Firmware : Obtain the official firmware from the Sunlu Support Site Custom/Marlin

: If you prefer the latest Marlin features or fixes (like proper fan assignments), you can find configuration files on the Marlin GitHub or pre-compiled community versions on Printables Rename the File : The firmware file must be named exactly firmware.bin . If the downloaded file has a different name (e.g., T3_V3.4.bin ), rename it before putting it on the card. Flash the Printer Turn the printer Insert the MicroSD card into the printer's slot. Turn the printer

The screen will stay blank for 10–30 seconds while the board updates. Once finished, the main menu will appear. Post-Update

: It is highly recommended to "Restore Defaults" and "Store Settings" (Save to EEPROM) in the printer's configuration menu to ensure no old settings conflict with the new firmware. Additional resources for Sunlu T3 users Official Support Community Firmware Calibration Downloads & Documentation Sunlu Official Facebook Support Updating the firmware on a Sunlu T3 (also

provides direct links to their official firmware repository for T3 32-bit boards. For the standard manual and slicing software setup, visit Scribd's hosted User Manual for detailed operation steps. Custom & Marlin Builds denizkoekden's GitHub

hosts an archive of the official source code for those who want to compile their own Marlin 2.0 version.

A popular pre-compiled version with 5x5 Bed Leveling and higher temp support is available on Printables by Kaot93 Setup & Optimization Anson Liu's technical blog

details the controller board electronics and why certain firmware fixes are necessary for the cooling fans. Are you updating to fix a specific bug

, such as the extruder cooling fan issue, or are you looking to install a for bed leveling? AI responses may include mistakes. Learn more

Updating the firmware on a Sunlu T3 (also known as the "Terminator") is a common procedure used to resolve issues like z-axis squashing, enabling PID tuning, or adding advanced Marlin features. The Sunlu T3 uses a 32-bit controller board that is largely a clone of the BigTreeTech SKR Mini E3 V2, which makes it highly compatible with standard Marlin firmware. Finding the Firmware

You can choose between official stock firmware or community-modified versions depending on your needs:

Official Stock Firmware: Sunlu provides firmware files on their official website or through their Official Facebook Support. Version v3.43 is a notable overseas release that supports both Chinese and English.

Custom Community Firmware: Many users prefer custom builds to unlock features like 5x5 Automatic Bed Leveling (ABL) or higher hotend temperatures (up to 285°C). Popular community sources include:

Kaot93's Custom Firmware: Available on Printables, this build improves bed tramming and filament runout detection.

Anson Liu’s Marlin Configuration: For users who want to compile their own, Anson Liu provides a Marlin 2.0 configuration that fixes bugs like the extruder cooling fan being misassigned.

GitHub Archives: General archives of the official firmware can also be found on GitHub for developer use. Update Procedure (SD Card Method)

The Sunlu T3 features a bootloader that allows for easy updates via the microSD card slot. SUNLU T3 Marlin Configuration and Controller Board Pictures

To update the firmware on your , you will primarily use an SD card to flash a file directly to the printer's 32-bit motherboard. 1. Prepare Your Hardware

uses a 32-bit ARM-based controller board (similar to a BTT SKR Mini E3 V2) . To perform the update, you need: Micro SD card (ideally 8GB or smaller). A computer to format the card and download files. 2. Download the Firmware File

You can obtain the necessary firmware from official or trusted community sources: Official Firmware : Historically available on the Sunlu Website (Version 3.40 is a common stable release). Official Archive : A copy of the official firmware is archived on GitHub by denizkoekden Custom Marlin

: For advanced features like better fan control or refined Z-offset menus, community-optimized versions are available on Printables by Kaot93 3. Format the SD Card

The printer requires a specific format to recognize the update file: Insert the SD card into your computer. Format it as 4096 allocation unit size Ensure the card is empty before proceeding. 4. Flash the Printer Rename the File : Ensure the downloaded firmware is named exactly firmware.bin

. If the file has a long string of numbers or dates, the printer may not recognize it. Copy to SD : Move the firmware.bin file to the root directory of the SD card (not inside any folders). : Turn off your Insert Card : Insert the Micro SD card into the printer’s card slot. Fix bugs and issues : Firmware updates often

: Turn the printer on. The screen will remain blank for about 15–30 seconds while it flashes the new code. : Once the main menu appears, go to About Printer to verify the new version number. Printables.com Important Post-Update Steps Reset EEPROM : It is highly recommended to go to Configuration > Restore Defaults Store Settings

immediately after updating to ensure old settings don't conflict with new firmware.

: Re-calibrate your Z-offset and level the bed, as these settings are often cleared during a flash. custom Marlin profile for the Sunlu T3 to enable specific features like Linear Advance denizkoekden/SUNLU-T3 - Marlin 3D Printer Firmware - GitHub

Updating the firmware on a is a straightforward process because the printer's board (an Ender 3 clone

using a modified SKR Mini E3 V2) supports flashing directly via the Micro SD card slot. Preparation Requirements Micro SD Card : Use a blank card (8GB or smaller is recommended). : The card be formatted to with an MBR partition map. Firmware File : A compiled file. You can find official versions on the Sunlu Website or custom Marlin builds from community members like Kaot93 on Printables Step-by-Step Update Guide Prepare the Firmware File Download your chosen firmware file. Rename the file to firmware.bin

exactly. If you have updated before, ensure the name is different from the previous update (e.g., firmware_v2.bin ) as the board may ignore a filename it has already "seen". Copy to SD Card file in the root directory (not inside any folders) of your formatted Micro SD card. Flash the Printer the printer. Unplug any USB cables connected to the printer.

Insert the Micro SD card into the printer's slot (contacts facing for the T3). the printer. Wait for Completion The screen will remain blank for approximately 10–20 seconds while the board installs the new software. Once finished, the main interface will load automatically. Post-Update Reset Navigate to Configuration Restore Defaults

(or "Initialize EEPROM") to ensure no old settings interfere with the new firmware. Save Settings to confirm the reset. Important Notes USB Warning

: Some custom firmware builds (like the popular Kaot93 version) may disable USB functionality. Check the specific file of your chosen firmware before flashing. : After updating, you will likely need to re-calibrate your and run an Auto Bed Leveling (ABL) sequence, as these values are often wiped during the reset. Printables.com specific firmware version for a feature like BL-Touch or high-speed printing? Custom Firmware for SUNLU T3 by Kaot93 - Printables.com

Here’s a concise review of the Sunlu T3 firmware update process based on common user experiences and technical notes.

3. How to Update the Firmware (Step-by-Step)

Once you have the firmware file (usually a .bin file), follow these steps carefully.

2. Where to Download the Sunlu T3 Firmware

Sunlu is notorious for making firmware difficult to find. They typically do not host files on their main website. You have three reliable options to get the latest file:

Option A: Official Support (Best for Safety) The most reliable way to get the correct firmware for your specific batch of the T3 is to email their support team directly.

• Email: service@sunlu.com
• Request: "I own a Sunlu T3. Could you please provide the latest firmware file and update instructions?"

Option B: Sunlu Facebook Group (Fastest) The Sunlu 3D Printer User Group on Facebook is very active. The community moderators often pin the latest firmware files for the T3, S8, and S9 in the "Files" section or "Announcements."

Option C: The "Clone" Method (Advanced Users) The Sunlu T3 is mechanically and electronically very similar to the Creality Ender 3 / Ender 3 Pro. In many cases, users have successfully flashed standard Ender 3 firmware (like the "TH3D Unified Firmware" or standard Marlin) onto the T3.

• Warning: Only do this if you are comfortable with compiling firmware or using pre-compiled binaries meant for the specific motherboard inside the T3 (usually a GD32F303 or ATmega1284P based board).

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Step 1: Prepare the SD Card

The motherboard is very picky about how the file is read.

1. Take a MicroSD card (preferably 8GB or 16GB, avoid 64GB+).
2. Format the SD card to FAT32 file system.
   • Windows: Right-click the drive > Format > File System: FAT32.
   • Mac: Disk Utility > Erase > Format: MS-DOS (FAT).
3. Copy the .bin file to the root directory of the SD card. Do not put it inside a folder.

What’s Good ✅

• Fixes thermal runaway bugs – Early T3 units had false thermal runaway triggers; updates resolve this.
• Improves mesh bed leveling – Some versions better store and recall ABL data.
• Silences stepper motors – Later firmwares enable better stealthChop settings for quieter operation.
• Adds features – Like manual filament change, baby-stepping, and power-loss recovery (though the last is controversial).

After the Update

1. Check firmware version again in settings – it should match the new one.

2. Run initial setup

   • Home all axes.
   • Re‑level the bed (mesh data is often erased).
   • Set Z‑offset again.
   • Calibrate e‑steps if the update changed them.

3. Test print – A simple 20mm calibration cube is perfect.

9) Troubleshooting

• Printer unresponsive after flash:
  • Power cycle; check wiring; try re‑flashing; enter bootloader and reflash.
  • If bootloader damaged, you may need an ISP programmer (ST‑LINK, JTAG) to restore.
• Motor directions reversed: change axis_invert in firmware or invert wiring.
• Thermistor errors: confirm thermistor type in firmware; check wiring and ADC channels.
• Bed/Hotend temps off: run PID tune and confirm thermistor table.
• SD card not recognized after flash: reformat FAT32, move firmware file if needed.
• If display blank: ensure display firmware or driver is compatible; some TFTs need a matching firmware file.

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Phase B: Updating the Mainboard (STM32 / Robin Nano)

1. Rename the file. Download the mainboard .bin file. Rename it strictly to firmware.bin (all lowercase). If your board requires Robin_nano.bin, use that instead.
2. Copy to SD. Place firmware.bin in the root directory of the SD card. Do not put it inside a folder.
3. Power off the T3. Ensure the printer is completely off using the rear rocker switch.
4. Insert SD card into the T3’s mainboard slot (usually located on the side of the screen housing or directly on the motherboard panel – check your manual).
5. Turn on the printer. The screen will remain blue or blank for 10–30 seconds. Do not touch anything.
6. Look for the indicator. On most Robin boards, the red LED will flash quickly, then go solid. The screen will eventually load.
7. Remove the SD card. Once the printer boots to the main menu, turn it off, remove the SD card, and delete the firmware.bin file from your PC. If you leave it on the card, the printer will re-flash every time you reboot.

1) Before you update — why and precautions

• Why update: fixes, improved print quality, new features, better stability, bug/security fixes.
• Risks: failed update can brick the printer or change behavior (e.g., thermistor/stepper settings).
• Precautions:
  • Back up current settings and any custom start‑up G‑code.
  • Save/record current firmware version (Printer menu → About/Info or M115 G‑code).
  • Ensure stable power (avoid power loss during flashing). Use a UPS if available.
  • Use the correct firmware for your exact board and hardware revision.
  • Read the changelog/release notes for the firmware you intend to install.
  • If printer is under warranty, check warranty terms before flashing third‑party firmware.

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