The Sunlu T3 is a Cartesian FDM 3D printer (a clone of the Artillery Hornet / modified i3 design). It runs on a 32-bit board (usually a proprietary STM32-based variant) with a touchscreen UI. Unlike Marlin-based printers with LCD12864, the T3’s firmware is a specialized Marlin fork integrated with a GUI for its color touch display.
Key components managed by firmware:
If the UI becomes unresponsive or shows corrupt graphics: sunlu t3 firmware
Flashing the TH3D or stock firmware onto a Sunlu T3 is straightforward, but specific.
Safety is paramount in 3D printing, and the Sunlu T3 firmware includes active Thermal Runaway Protection. This firmware-level safety feature monitors the temperature sensors. If the firmware detects that the heating element is powered but the temperature is not rising (or is rising uncontrollably), it automatically cuts power to prevent hazards. This is a critical feature that distinguishes reliable modern printers from older, unsafe clones. The Sunlu T3 is a Cartesian FDM 3D
While this article focuses on Marlin, advanced users are migrating the T3 to Klipper. Because the T3 has a weak 8-bit or low-end 32-bit CPU, Marlin struggles with high-speed printing.
With Klipper (running on a Raspberry Pi or old laptop), the Sunlu T3 can achieve: Risks: You must compile Klipper firmware for your
Risks: You must compile Klipper firmware for your specific T3 MCU (usually STM32F103). You will permanently lose the stock LCD screen UI unless you install KlipperScreen on a touch display. This is for tinkerers only.
The Sunlu T3 is known for being a "budget workhorse," but its firmware is surprisingly capable for the price point. While not as flashy as Klipper, the stock Marlin-based firmware is stable and packed with essential features. Here is what you need to know.
| Symptom | Likely Cause | Solution |
|---------|--------------|----------|
| Homing fails, probe does not deploy | Wrong probe type in firmware | Recompile with Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN disabled |
| Touchscreen shows no response | Firmware mismatch between mainboard and screen | Flash both mainboard and DWIN firmware |
| "TMC CONNECTION ERROR" | UART pins not configured | Update to post-2023 firmware, or manually define in Configuration_adv.h |
| Thermal runaway after 10 min | PID values incorrect | Run M303 E0 C8 S210 U1, then M500 |
| Extruder steps/mm wrong (default 140?) | Old firmware used 400 steps | Set M92 E140 (for T3’s standard extruder gear ratio) |