6-Inch Flex Duct Adapter — Rigid Socket to Flex Collar

Description

Overview

The bridge between the rigid duct fittings in this line and real HVAC flex duct. One end is a 152.4 mm OD plug that seats in any 6-inch duct-fitting socket in the catalog (bore 153.0 mm or larger); the other end is a male flex-over collar — clamp land 150.4 mm, retention bead crest 152.4 mm — that 6-inch flex duct slips straight over.

What it deliberately does not fit: shroud collars. Every D-Central shroud already carries its own flex-over collar, so this plug is an interference fit against a shroud collar by design (measured −0.041 mm radial). Connect flex duct to a shroud directly — this adapter is for the rigid duct fittings: couplers, elbows, reducers, window ports and wyes.

What it fits

• Any 6-inch duct-fitting socket in the D-Central line (bore 153.0 mm or larger): couplers, elbows, reducers, window ports, wyes.
• 6-inch flex duct, which slips over the collar end and clamps on the land.
• Not shroud collars — interference by design; shrouds carry their own flex collar.

Measure before you order. Fit dimensions in this line are derived from published fan and chassis geometry and are not yet validated against measured production hardware. Check your flange size and clearances against the footprint below. If something does not fit, tell us — that is how the next revision gets better.

How it is used

Push the plug end into the socket of the fitting you want to convert — an elbow that must continue in flex, a window port fed by a flex run, a coupler joining flex to rigid. Then slip the flex duct core over the collar end and clamp it on the land, below the bead. That is the whole job: one part, one clamp.

Why it helps

• Lets one duct run mix rigid fittings and flex duct wherever each makes sense, instead of committing to one.
• Replaces the improvised tape-and-hope transitions that flex-to-rigid joints usually get.
• Same collar geometry as every other 6-inch flex interface in the line, so clamps and habits carry over.
• Honest status: flex retention is a geometric design (land 150.4 / crest 152.4 / bore 145.6 mm), not yet a tested fit against measured duct hardware.

Specifications

Open source

This design is open source under CC BY-SA 4.0. The files are free to download at /3d-models/, and anyone may print, modify or sell them — that is the point. Buying a finished part from us is one way to support the work; the fund is another.

Works with

Converts these rigid-socket fittings to flex:

• 6-Inch Duct Coupler
• 6-Inch 45° Duct Elbow
• 6-Inch Window Vent Port (rigid)

See the full D-Central shroud and ducting system.

Frequently asked questions