Solving Bambu Lab A1 Extruder Motor Overheat: A Practical Guide

When printing larger items, some users of the A1 and A1 Mini series 3D printers have reported frequent clogging due to motor overheat. This issue can be particularly frustrating, as it affects print quality, especially during extended or more complex jobs. After testing multiple printers, we discovered that only one out of four units exhibited this overheating problem, despite swapping motors and transfer boards. The conclusion? A likely firmware issue with Bambu Lab, but thankfully, there’s a mod that provides a reliable fix.

Why Overheating Happens and Why It Matters

Stepper motors in 3D printers generate heat during operation. Typically, this is manageable, but under certain circumstances—like when printing large models—this heat can transfer to the extruder, causing the filament to soften prematurely. When the filament softens, it often leads to nozzle blockages, which result in printing failures. Here’s why motor overheating is particularly troublesome:

• Clogging During Larger Prints: Larger prints put more strain on the motor, especially when printing continuously for extended periods. The heat buildup in the extruder motor increases the chances of clogging.
• Heat Transfer from Motor to Filament: Over time, as the motor heats up, it transfers that heat to the extruder assembly. This can cause the filament to melt prematurely, leading to feeding issues and eventually clogging the nozzle.
• A Potential Firmware Issue: Despite swapping components like the motor or transfer board, this overheating problem persisted in one of the test printers. We concluded that it’s likely an issue with the Bambu Lab firmware.

Cooling Solutions for the A1 and A1 Mini Extruder Motor

While the firmware may be at fault, an effective hardware solution exists: cooling the motor with a fan. Here’s how to do it:

1. Using the AMSlite Interface Power Supply (24V)

• If you use a 24V fan, you can connect it directly to the AMSlite interface on the printer. It’s a simple setup that doesn’t require any significant modifications. The 24V fan is sufficient for cooling motors of the A1 and A1 Mini series since they all share the same motor specifications.

1. External USB Power Supply (5V)

• If you prefer a 5V fan, you can power it using a USB charger. This option is great for users who want an easy plug-and-play solution, although it’s generally less powerful than the 24V fan.

1. Extruder Motherboard Modification (5V Fan)

• For more advanced users, you can modify the extruder’s motherboard to supply power to a 5V fan. Although effective, this method involves modifying your printer’s internal wiring, which could void the warranty. If you decide to proceed, follow this guide on Makerworld to ensure a proper setup.

Recommended Cooling Fan Brackets

To cool the A1 or A1 Mini extruder motor effectively, a properly designed fan bracket is crucial. Here are a few reliable designs from Makerworld:

• A1 Series Extruder Motor Cooler Housing.
• This housing is designed to hold a 4010 24V fan. Initially, a 3010 fan was considered, but testing revealed that the 4010 offers better airflow. You can attach a KSD9700 temperature control switch to the motor to automatically control the fan’s on/off operation. While effective, note that using an outer cover with a grille may increase fan noise.

• 3007 Circular Fan Bracket
• This bracket fits a 3007 circular fan (30mm in diameter, 7mm in height). It’s a compact and lightweight option, ideal for users who want a smaller fan. While this fan runs at 14,000 RPM, it may not be necessary to run it at such high speeds.

• 3010 5V Fan Bracket
• For users going the 5V route, this bracket fits a 3010 fan and can be powered through a USB source. Check the detailed assembly guide to ensure proper installation.

Conclusion: Practical Fix for A1/A1 Mini Extruder Overheating

While the overheating problem appears to stem from a firmware issue in some cases, adding a cooling fan is a straightforward solution that can prevent nozzle clogging and improve overall print reliability. Whether you choose a 24V fan powered by the AMSlite interface or a 5V fan connected via USB, this mod ensures that your motor stays cool during long print jobs, saving you from the frustration of failed prints.

Install a cooling fan, follow the guidelines, and keep your A1 or A1 Mini running smoothly, even on those larger prints!