This is a lightweight, efficient fan duct designed for the Anycubic Kobra S1. By optimizing the airflow directly through the heatsink, it improves cooling efficiency, prevents heat creep, and helps eliminate frustrating filament clogging issues.

Note on Acoustics: Several users have reported that the added backpressure alters the acoustics, making the stock fan subjectively quieter by reducing the high-frequency whine.

IMPORTANT!

Before use, make sure that the mod does NOT touch the heatsink; otherwise, it may affect the leveling. There is also a version with higher tolerances.

A user told me that he cannot use this model with the original fan duct. It works with my original fanduct, but there may be different versions. Since the cooling performance of the original fan ducts isn’t impressive anyway, I highly recommend https://www.makeronline.com/en/model/Kobra%20S1%20Fan%20duct%20optimised/175793.html?trackModuleType=8, which is definitely an upgrade.

Updates & Versions

UPDATE 26.06.2026:

• Full Rework: I have overhauled and updated all versions today. It came to my attention that newer revisions of the original factory fan duct/cover caused clearance issues, so these changes ensure proper fitment across different machine batches. Please re-download the latest files if you encountered problems!
• EXTRA Clearance Version: Added a version with a full 1mm extra gap in case your printer has tighter tolerances.
• Microswiss Hotend Support: Thanks to @rp86, we now have a dedicated version for the Microswiss hotend!

To keep things organized, every single version is available for both M2.5 and M3 screws.

Key Features & Compatibility

• Universal Print Cover Compatibility: Designed with clearance in mind. It fits under all print covers/shrouds.
• No Leveling Interference: It should NEVER touch the heatsink ( please check in advance )  or the load cell. Your auto-bed leveling system remains unaffected.
• Bambulab Hotend Ready: For those who have modded their printer, the Standard and EXTRA Clearance versions fit perfectly if you are running a Bambulab hotend conversion.
• Microswiss Hotend: Choose the dedicated version if you are rocking the Microswiss hotend on your S1.
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 Hardware Requirements

Choose the file depending on what hardware you have on hand:

• M2.5 Version: For two M2.5 screws.
• M3 Version: For two M3 screws.

Required Screw Lengths:

• Standard & EXTRA Clearance: Recommended length is 15mm (slightly shorter or longer screws could work as well).
• Microswiss Version: The screw must NOT be longer than 12mm.

 Print Settings

• Supports: No / None (designed to print without supports)
• Print Time: ~10 minutes
• Filament Used: ~0.5g
• Material Recommendation: PETG, ABS, ASA, or high-temperature engineering filaments.

⚠ CRITICAL NOTE: PLA is NOT recommended, as it will deform near the hotend over time.

 Installation

Installation is straightforward and takes only 5–10 minutes. Simply mount the duct using your chosen screws, ensuring it sits firmly against the fan to properly direct the airflow into the cooling fins.