Popular fittings › Rectangular duct reducer
Rectangular duct reducer
Independent rectangular end profiles for low-clearance duct runs. Free 3D printable reducer.
Open in the designer →
Opens with the sizes below. Change anything, then export 3MF, STL or STEP. Free, no account, runs in your browser.
Starting sizes
| End | Inner size | Connection |
|---|---|---|
| Inlet | 120 × 70 mm | Smooth sleeve |
| Outlet | 70 × 40 mm | Smooth sleeve |
Need another size? Every dimension is editable in the designer, in millimetres or inches.
What it is
Changes between two rectangular duct sizes.
How to measure
For a rectangular end, measure the inside width and height of the duct or opening it joins, or its outside size if the fitting slides inside it.
Print tips
- The export already places every component in its recommended print orientation. Keep supports off sleeves, sockets and any sliding or tight-fit surface so they stay smooth; if your slicer asks for supports, paint them only where an outside overhang needs them.
- Use 3–4 perimeters for an airtight wall; infill matters much less than wall count for ducts.
Frequently asked questions
- What size should I measure?
- For a rectangular end, measure the inside width and height of the duct or opening it joins, or its outside size if the fitting slides inside it.
- What should I print it in?
- PLA or PETG both work for dust collection at room temperature. Print in PETG or ASA if the air is warm or the part sits in the sun. Use 3–4 perimeters for an airtight wall; infill matters much less than wall count for ducts.
- What hardware do I need to buy?
- Nothing is required at these starting sizes: it prints in one piece. A hose clamp is optional if a hose feels loose.
- Does it need supports?
- The export already places every component in its recommended print orientation. Keep supports off sleeves, sockets and any sliding or tight-fit surface so they stay smooth; if your slicer asks for supports, paint them only where an outside overhang needs them.
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