QIDI Q2 fan duct - comparing alternative designs

Update 30/08/2026

To complete the update started on 28/08/2026, I am adding to this project two sets of STEP files:

1- The QIDI design with the modifications needed to match the original ABS parts.

These changes include my best guess for the original dimensions a reduced chamfer on the top part curved surface. In the original design, this chamfer ends in a sharp edge that is difficult to print and detach from needed support. The chamfer is reduced just enough so that the first layer above the support contain two material lines (2x0.4=0.8mm). This makes the print easier and more robust.

This can be used as a starting point for anyone willing to make custom designs.

2- My latest design (version 8).

Built on the above model, includes further changes to the original parts. Has an increased volume to help more air reach further to the front side. The bottom part is also modified to allow fixation using screws on the front side.

Use two M2x8mm DIN EN ISO 2009 (or identical). With some care and patience the screw will cut a thread in the plastic hole. This is aimed at eliminate the tendency of printed parts (ASA in this case) to warp under heat, as can be seen in the picture below.

This design achieves reasonable balance of air flow between the left and right sides of the nozzle, but you can feel that a better balance is possible. I have been using it for a month now. Printing results are quite ok.

To try to increase the heat resistance, I’ve printed this same part in ABS GF, but not tested yet (ASA has being holding on without melt/deform).

Both these designs are provided in a ZIP file, containing both parts (one STEP each) and the respective assembly (a third STEP).

For the moment, this is working for my needs. As mentioned before, I think I need a better test to be able to reliably evaluate the different designs. So, for the now, I am stopping with this project.

Update 28/08/2026

Almost immediately after running the testing below and chosen a design to replace my (damaged) original fan duct (QIDI original fan ducts were out of stock at that time), I've printed new parts based on QIDI provided 3D models (from QIDI wiki) and noticed that print results were bad and inconsistent. I did print several versions but all were giving much worst results than my tests had shown. It did not take long to perceive that the models in the QIDI wiki were not matching the fan duct I received with my printer. Recently I got a new original fan duct (there is currently stock) and I am posting a photo here of the original and the printed one (which is somewhat melted due to being used for some time). Can you spot any differences???

This enormous increase in the slot dimensions explain the bad performance (poor/uneven part cooling) and probably also explain my previous results: the parts that performed better used the original top duct part, although partially deformed. All the others used printed top parts modified (but without changes in the slot height).

So, I suspect that all this effort was invalidated by the wrong geometry in the QIDI provided parts...

As I got the new original fan duct from QIDI (and have an un-deformed parts for reference), I confronted QIDI with this fact and requested a corrected file. I got this:

Exactly the same as I downloaded months ago...

In the time between all these events, I managed to modify the QIDI models to match the actual parts, made some modifications to allow manual placement (and removal) of magnets, improve the fixation of the bottom part and some other modifications to help improve and balance the air flow. I intend to publish some of these files here, soon (I need to choose the models and generate the STEP files).

What I was not yet able to do is to compare them (and take conclusions). Preliminary tests gave consistently worst results than the previous best. So, I am a bit unsure about which test(s) to use to get more consistent outcomes (a test tower as previously? a benchy? Something else? Ideas are welcome) . 

Original text

My Q2 fun duct melted partially. Original parts were out of stock. Search for alternatives, provided some ideas and the need to compare alternatives.

In this project, I compare the original QIDI fan duct design with some ideas that built up during the investigation. Also used an existing design

that seemed interesting to test. 

Check the attached PDF for details, results and conclusions.