4 Inch Magnetic Exhaust Pipe Coupler System

UPDATE:

I have added two new files for 80mm outer diameter male couplers in both the 30 and 45mm tall version!

This project is my first full Fusion 360 design, created to help me more effectively manage and improve my 4" exhaust setup. I’ve been 3D printing for about two years, and building this system has been a huge step forward in growing both my design skills and my overall 3D printing abilities. I’m excited to share it with everyone and look forward to continuing to learn, improve, and create more useful projects for the community.

This is a fully modular 4‑inch (100 mm) magnetic coupler system designed for fast, tool‑free connections across a wide range of airflow applications, including 3D printer exhaust, portable air conditioners, clothes dryers, and workshop dust collection. All components are optimized for FDM printing and assemble using strong neodymium magnets for a reliable, airtight fit.

Included Components

• Two Male Couplers (100 mm outer diameter)
  • Available in 30 mm and 45 mm lengths for space‑saving installations
• Female Coupler (100 mm inner diameter)
  • Designed to clamp over an exhaust pipe
  • Features relief cuts and alignment ribs for a secure hose‑clamp fit
• TPU Gasket (Optional)
  • Compresses between couplers for improved sealing
  • Recommended to lightly tack in place with superglue if used
• Magnetic Cap
  • Fits over either male or female couplers
  • Ideal for blocking hot or cold drafts when the system is not in use
  • Features large, knurled handle for easy removal
• Wall Mount Bracket
  • Three mounting holes:
    • Two outer holes for maximum strength
    • One center hole for single‑screw mounting
  • Serves as a convenient place to store the end of your exhaust hose or the magnetic cap when not in use

Supplies Needed

• 6 - 18×3 mm neodymium magnets per coupler
• Superglue or adhesive of choice 
• Hose clamp for attaching the female coupler to an exhaust pipe and for attaching flex tubing to the male couplers

Magnet System Installation

Each coupler uses six 18×3 mm neodymium magnets, arranged to provide strong, repeatable snap‑fit alignment between any compatible parts.

To identify magnet polarity, the method that worked best for me was to take two magnets and bring their faces together. The sides that repel each other are the same pole — I mark both of those faces with an N for north, and the opposite faces with an S for south. Be sure to do this with all the magnets you plan to use at once to make sure you don't get polarities mixed up in a different batch of couplers.

When installing the magnets, alternate the polarity for every other magnet (N‑S‑N‑S‑N‑S). This alternating pattern allows the couplers to lock together in three different rotational orientations while maintaining consistent magnetic attraction.

Once polarity is confirmed, secure each magnet in its pocket with a small amount of superglue or your preferred adhesive to ensure they stay firmly in place during use.

Printing Notes

• No supports required — all models are designed to print cleanly in their default orientation
• Use at least 3 wall loops to ensure the coupler walls are strong and fully solid
• Low infill (around 10%) is perfectly fine, as most of the strength comes from the walls
• Minimum recommended material: PETG for durability and heat resistance
• For higher‑temperature applications such as heated 3D printer chambers or dryer exhaust use, ABS or ASA is recommended for the best long‑term performance
• For the TPU gasket, a low layer height gives the best flexibility and sealing performance. I used 95A but i wouldn't go much lower than 85A.

Design Notes

I’m still learning Fusion 360 and growing my design skills, so if you’d like a modification or a variation of this system, I’m happy to try making adjustments within my current ability. My schedule is usually pretty busy, but I’ll do my best to help when I can.

Thank you to everyone who downloads and enjoys this model!