Popular fittings › Round to rectangle adapter
Round to rectangle adapter
Loft a round inlet into a fully adjustable rectangular outlet. Free 3D printable, export 3MF, STL or STEP.
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 | 100 mm (3.94 in) | Smooth sleeve |
| Outlet | 120 × 60 mm | Smooth sleeve |
Need another size? Every dimension is editable in the designer, in millimetres or inches.
What it is
A smooth transition from a round hose to a rectangular duct, register or opening.
How to measure
For each end, measure the hose, pipe or port it joins with calipers. If that part slides into the fitting, measure its outside diameter and keep “Measure by: Inner diameter”. If the fitting slides into a hose, measure the hose’s inside diameter and switch to “Outer diameter”. Measure twice across the circle; flexible hose is rarely perfectly round. 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 each end, measure the hose, pipe or port it joins with calipers. If that part slides into the fitting, measure its outside diameter and keep “Measure by: Inner diameter”. If the fitting slides into a hose, measure the hose’s inside diameter and switch to “Outer diameter”. Measure twice across the circle; flexible hose is rarely perfectly round. 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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