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Adapters & couplers
Square to round duct adapter, 100 mm
A transition piece that connects a 100 mm round ventilation hose to a 110 x 110 mm square wall grille or fan housing, common in bathroom extract fans and small workshop ventilation. The round end is a 99.6 mm spigot 40 mm long that fits inside the hose, and the square end is a socket with a 20 mm flange carrying four 4.5 mm screw holes. A 40 mm morphing section with 2 mm walls keeps airflow smooth, and printing with the flange down needs no supports. Open the ready-made model free, resize it on your phone or computer, then download a print-ready STL, 3MF or G-code sliced for your printer, free.Opening the ready-made model and downloading it as STL or 3MF are free, no card; AI changes use credits, from Maker at $7.99 a month.No printer? We print this part and ship it to your door. See its priceUpdated
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Adjust
Change its numbers in the viewer for free, or ask the AI in the chat: wall thickness, hole size, the thing it clips onto. AI changes use 2 credits per request (1 for a quick edit, 3 for a redesign), paid with a plan from Maker at $7.99 a month.3Print
Download a watertight STL or 3MF free, with your numbers and hand edits, or G-code sliced for your printer at the same price. After an AI change the download is included in every plan (4 credits without one).
Dimensions of the ready-made model (editable)
| Parameter | Value |
|---|---|
| outer square side | 110 mm |
| wall thickness | 2 mm |
| socket depth | 15 mm |
| flange width beyond square | 20 mm |
| flange thickness | 4 mm |
| bolt hole diameter | 4.5 mm |
| transition height | 40 mm |
| spigot outer diameter | 99.6 mm |
| spigot length | 40 mm |
Example prompt
Design a square-to-round duct adapter. Square end 110x110 mm socket 15 mm deep with a 20 mm wide flange and four 4.5 mm holes at 130 mm spacing. Round spigot 99.6 mm outer diameter, 40 mm long. Smooth lofted transition 40 mm long, 2 mm walls throughout.
Fit notes
Duct sizes and grille openings never quite match the parts in the shop, but SpeakCAD draws the transition to your two measurements and the depth you have behind the wall. Preview in your browser and ask for a 45-degree offset, a longer spigot or a gasket groove.
Questions people ask about a square to round duct adapter, 100 mm
A transition piece that connects a 100 mm round ventilation hose to a 110 x 110 mm square wall grille or fan housing, common in bathroom extract fans and small workshop ventilation. The round end is a 99.6 mm spigot 40 mm long that fits inside the hose, and the square end is a socket with a 20 mm flange carrying four 4.5 mm screw holes. A 40 mm morphing section with 2 mm walls keeps airflow smooth, and printing with the flange down needs no supports.
Click Open it free on this page and create a free account (no card): the ready-made model opens in your browser, on your phone or computer, nothing to install. Change its numbers in the viewer for free and download a watertight STL or 3MF free, or G-code sliced for your printer at the same price. An AI change in the chat uses 2 credits per request (3 for a redesign), and the download after it is included in every plan (4 credits without one). Start with Maker: 50 credits a month for $7.99, cancel anytime.
On this page: open the ready-made model free in a SpeakCAD account (no card), change any dimension in the viewer, then download the STL or 3MF free, or G-code sliced for your printer at the same price.
A shared STL is modelled for someone else's measurements. Here you open the ready-made model free, change it to your measurements in the viewer, then download a file sized for the part you actually own, free as STL or 3MF.
Yes. SpeakCAD slices the part on its servers with OrcaSlicer and your printer's official profile (380+ printers, including Bambu Lab, Prusa, Creality and Elegoo), and you download the G-code (a sliced .gcode.3mf for Bambu Lab printers). G-code sliced for your printer costs the same as the STL: included in every plan, free for a part you shaped by hand, 4 credits without a plan for a part with AI work in it. Pick your printer on the printers page to see its profile.
No. SpeakCAD runs in the browser on your phone or computer: the chat, the 3D engine and the live viewer load in the tab. The only file you download is the finished STL, 3MF or sliced G-code.
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