May 26, 2026
Description
I have a Laser Cutter and AC Infinity 6” Inline Duct Fan requiring an adapter to reduce the 6” fan inlet to the 4” ducting from the laser. Initially, I purchased the AC Infinity Duct Adapter, 6” to 4” Ducting Reducer, but as some of the reviews indicate the fan side is too loose to remain attached to their own fans (due to design and/or quality control). I found this to be a problem for me as well, especially considering I wanted to install the fan vertically with the inlet side pointed down.
Design and print a duct reducer with the following objectives:
Parametric allowing customization of both diameters (this allows it to be configured as an expander or even a coupler), transition length, insert depths, wall thicknesses, size and placement of the ducting ridge stop, tolerances, and any other design dimension
Smooth airflow
Snug fit and airtight as much as possible (frictiontolerance parameter)
Print with no supports
Look good
New! Added OpenSCAD model with the same user parameters available in the Customizer window. I was happy to add this, but please note that Autodesk Fusion is free for hobby use and provides more flexible features at the cost of some learning on your part. If you can understand OpenSCAD, you can figure out Fusion!
Fixed Fusion model to properly generate the full shell thickness at the ducting end
Modified the .f3d file only (all other files remain v1.1) to add a constraint ensuring the duct stop stays attached to the main part when resized.
Modified the .f3d file only (all other files remain v1.1) to greatly simplify the design approach - my original approach was definitely on hard mode 😆. It also adds an optional stop on the “fan” side for those who want to use it to connect two pieces of ducting and/or as a ducting coupler with two pieces of ducting with the same diameter.
To enable the fan side stop, unsuppress the last feature in the timeline. Also, please note that the “fan” side diameter is specified from the inside while the “ducting” side diameter is specified from the outside. So, you'll need to set DuctReducerFanEndDiameterInner to 2 * DuctReducerShellThickness less than the diameter of the ducting on that end. For example, if you're trying to design a coupler, you would set DuctReducerFanEndDiameterInner to DuctReducerDuctingEndDiameterOuter - 2 * DuctReducerShellThickness).
Modified the .f3d file only (all other files remain v1.1) to align the calculation of the DuctReducerFanEndDiameterInner parameter to my other designs. I have adjusted the values for each of those parameters so that the DuctReducerFanEndDiameterInner parameter will still calculate to the same value as before (default 146.40 mm) resulting in the same model geometry. But once you start adjusting either of the following values, they will now affect the fan end geometry as follows:
XYPrintingTolerance is now added to the diameter (previously subtracted) and multiplied by 2
DuctReducerFanEndFrictionTolerance is now multiplied by 2
New! Added MagDuct compatibility!
v2.0 of the .f3d file is MagDuct only
MagDuct compatibility adds new features explained at the link above.
v1.4 of the .f3d file will remain available if you don't care about MagDuct (all MagDuct files start with MagDuct).
v1.1 of the non-MagDuct model and print files are still the latest versions.
The included model fits my original use case with these key parameters:
148 mm fan outer diameter for AC Infinity 6" Inline Duct Fan (Amazon.com)
99 mm ducting end diameter for AC Infinity 4" Flexible Aluminum Ducting (Amazon.com)
The Fusion file is included. You can customize the parameters (DESIGN | SOLID | MODIFY | Change Parameters) as necessary. When you open the Parameters dialog, first sort by name. The parameters most optimized for customization are favorited. The non-favorited parameters should work as well but may require more tinkering to repair broken downstream features.
See the attached .3mf for my settings. Use 100% perimeters. Supports are not required.
Consider slicing a small cross section (e.g. the first 1-2 mm) of the fan end to verify a snug fit on your fan before printing the entire model.
I printed with Prusament Jet Black and it’s a good match to the AC Infinity Fan and Ducting.
I prototyped on a Prusa CORE One.
Hopefully, you nailed your dimensions and tolerances before printing the entire model. If it is a little too snug, you can try to expand the fan end by heating it with a heat gun. This technique would probably not work well if you printed it too big though.
If this model helped you solve a problem, save some time, or in any way made your life a little easier then please consider clicking the Like button and posting your Makes! If it fell short after clicking on the title of the model, please let me know (Messenger | Printables.com). Either way, Thank you!
xTool P2 Exhaust Duct Adapter (configured as 4 in)
MagDuct xTool F2 Ultra UV Slip Adapter
MagDuct CORE One Exhaust Adapter and Gasket
xTool pipe (included w/ xTool IF2 2.0 and xTool F2 Ultra UV)
xTool 72.5 mm ducting (included w/ xTool P2)
Duct Expander (configured as 4 to 6 in expander)
Ducting to Window Insert Connector (attached to a piece of 1/4" acrylic inserted in the channels of my double hung windows which allows for quick installation/uninstallation (configured as 148.0 mm (6") and 72.5 mm exhaust port)
MagDuct Fume Extraction Nozzle and Screen - Direct smoke and fumes (e.g., soldering) into exhaust ducting
MagDuct Generic Accessories - Control airflow volume and chamber temperature (e.g., enclosed 3D printers)
License:
Creative Commons — Attribution — Noncommercial
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Gizmo Goody
