8" Soffit Duct Vent with Dual Doors

This 8" soffit duct vent is designed for clean, functional ventilation using standard 8" flexible ducting. The design includes dual swing doors that help prevent backdrafts, pests, and debris from entering while still allowing proper airflow.

The assembly consists of four main components: a base duct for attaching your flexible duct, a vent cover, and two hinged doors. The base mounts directly to the soffit, while the vent cover attaches securely using four #8 flat head machine screws.

The doors are designed with a simple but effective hinge system using either 33.35mm x 2.5mm pogo pins or cut pieces of filament, making assembly easy and hardware optional.

Features

• Designed for standard 8" flexible ducting

• Dual-door design helps reduce backdraft and intrusion

• Clean soffit-mounted appearance

• Modular 4-piece design for easy printing and assembly

• Flexible hinge system using pogo pins or filament

• Secure vent cover attachment with 4 screws

Assembly Instructions

1. Prepare the Doors

   • Insert hinge pins using:

     • 33.35mm x 2.5mm pogo pins or

     • Cut lengths of filament

   • Slightly flex the doors during installation to seat the pins into the vent cover holes

2. Assemble Vent Cover

   • Install both doors into the vent cover (2 required)

3. Install Base Duct

   • Attach flexible ducting to the base duct

   • Mount the base to the soffit

4. Final Assembly

   • There are 8 holes in the vent cover that can be used to fasten to the base.  While all 8 screws can be utilized, only 4 are needed. When attaching to the soffit, insert the screws minimally on the door sides.  The additional screws can certainly be used if you prefer.
     Attach the vent cover to the base using 4x #8 flat head stainless steel machine screws.
     

Print Recommendations

• Material: PETG (recommended for outdoor durability and flexibility)

• No supports required (depending on orientation)

• Layer Height: 0.2mm (0.16mm for finer finish)

• Perimeters: 3–4 recommended

• Infill: 20–40%

Notes

• Slight flexing of the doors during installation is expected

• Filament hinge pins work well and eliminate the need for additional hardware

• Designed for typical soffit installations—verify fit for your application

• PETG is strongly recommended for outdoor use