Summary

Customisable conversion adaptor cowlings for fans of any size

Files you will find for this thing consist of STL files of some common conversions as well as custom jobs made on request, the beta OpenSCAD file for the Customizer, an older version of the native SOLIDWORKS file and a newer version of the native Inventor file.

The OpenSCAD file is primarily for customisation. As of now it is a very simple and inefficient model but should be able to make simple conversions that are not already available.

The Solidworks and Inventor files can be used for customising with very basic constraints that work for most sensible conversions. The layout of the file should be easy to follow for anyone with basic knowledge of the required software.

Using the customizer

Variables for use with The Customizer.

It seems at the moment the customiser is unreliable, so use it your own risk. Hope for the best, but expect the worst.

When it comes to low power fans there is a degree of de-facto standardisation, however this is not formalised in any way. This Customizer should at least allow people to work quickly with non-standard fans as well as choose other variables to suit their needs better than my ready made adaptors can handle.

The Customizer/OpenSCAD are very rough and unrefined and should be considered to be in early development. I am still coming to grips with the software and the language. However it should function fine when the size difference between fans is not too great. I will probably improve this as and when I get the chance.

As always, once created, make sure you check the resultant STL before printing it. Everything should function fine, but you can never be too careful. If the Customizer doesn't work for you and you need something special making, let me know and I will see what I can do, time depending.

The Customizer will ask you for 12 values. These are:

• holeaccess
  This dictates how you access the smaller fan's mounting holes. The options are:
  Cowling: Small fan screws accessed through the cowling.
  External: Small fan screws accessed from outside of the adaptor.
  Flange: A simple flat plate with mounting holes for both sizes.
  Some models work best with external access, some with cowling access, some it doesn't matter for. Experimentation is the best way to find the right option. The Customizer makes the "Cowling" and "Flange" options look messy, but they are fine once created.
• $fn
  This is the facet resolution and can safely be ignored.
• smallsize
  This is the smaller fan's given size. (e.g. 60 mm, 80 mm)
• largesize
  This is the larger fan's given size. (e.g. 92 mm, 120 mm)
• smallflange
  This is the thickness of the smaller side's mounting flange.
• largeflange
  This is the thickness of the larger side's mounting flange. This is also the thickness of the "Flange" option's flange.
• wallthickness
  This is the thickness of the wall of the cowling. The part that joints the two mounting flanges. This size is added twice to the small and large fan size to dictate the size of the mounting flanges.
• cowlingheight
  This is the height of the cowling between flanges. The total height of the adaptor will be this plus the two flange thicknesses. It is advisable to bear in mind the angle of the cowling when choosing a height, to ensure smooth and reliable printing and to a lesser degree, good airflow properties.
• smallholes
  This is the spacing between the screw holes on the small fan side. (e.g. 50 mm, 72 mm)
• largeholes
  This is the spacing between the screw holes on the large fan side. (e.g. 83 mm, 105 mm)
• smallholesize
  This is the diameter of the mounting holes on the small side. (e.g. 3.5 mm) Standard PC case screws tend to be around 4.5 mm, so bear this in mind when choosing your screw hole size.
• largeholesize
  This is the diameter of the mounting holes on the large side. (e.g. 4.5 mm)

As with the STL models, the default values for the customiser model are quite liberal and could be trimmed down if necessary. Customiser makes the "Cowling" and "Flange" options look messy, but they are fine once created.

Useful information & caveats

Regarding fan sizes

Some manufacturer's fans appear to have differing screw hole spacing in comparison to the majority. In those cases I have gone for the most common size among manufacturers.

Because of this, it is worth checking the dimensions of your chosen converter before printing. These items are all fairly quick and dirty and you should check and be certain they fit what you need before printing them.

If something seems wrong to you or not meeting your needs, please see the contact me section below.

Information on the design

The primary design variables in the model are the large and small fan sizes, their respective mounting hole spacing and their respective screw hole sizes. Additionally there are cowling and flange thickness variables as well as overall height.

All of the non-bespoke models have a certain overhang which will have to be attended to when printing. This overhang will either come from the mounting hole parts of the flanges, the counterbore on the smaller side and the smoothing around the flanges near the mounting holes. All tapers take account of the 45 degree rule of thumb.

Post-processing

Most of these will require some post-processing.

Filing of mounting holes is almost certainly going to be required along with cleaning up of the inner surfaces to ensure smooth airflow.

Edits

30th June 2014 edit: Added dodgy 2 x 80 to 120 mm thing and 40 to 25 mm. Added some new versions of 40-30, 50-30 and 50-40.

2nd July 2014 edit: Added quick CFD of the normal adaptor flow and the 2x80 adaptor. Clearly showing the inefficiency of design in the 2x80. Well, what can you expect for a quick job.

8th Feb 2015 edit: Added 25 mm to 30 mm. Very quick and dirty. I've been really busy with work recently so can't spend too much time on this at the moment. Screwing will be difficult, perhaps cable ties or wire wrap or string will do the job, at least temporarily.

21st May 2015 edit: Added 140 and 180 to 120 mm.

7th March 2016 edit: Added new 92 to 50 mm adaptors with corrected hole sizes on the 50 mm side. There are 2 versions, one with 40 mm spacing between hole centres for the 50 mm side and one with 42 mm spacing. This discrepancy comes about because of differences in datasheets from different manufacturers. So, before printing please be sure to check your dimensions.

18th March 2016 edit: Updated 60 to 30. Small side hole spacing was marginally too large.

6th August 2016 edit: Added a requested 92-120 mm with thicker construction, square flanges and 20 mm high.

3rd January 2017 edit: Updated 50-30 mm to account for hole spacing on the small side. Updated three other files with small geometry alterations. Added 90 degree bend converting from 60 to 40 mm.

6th January 2017 edit: Added two requested 140 conversions.

12th March 2017 edit: Added 80 mm to 40 mm offset adaptor by request. Very quick and not going to be very flow efficient, but will do the job to a certain extent.

11th April 2017 edit: Added 140 mm to 120 mm with offset adaptor by request. Check sizes and spacing before printing please.

12th April 2017 edit: Added a very simple OpenSCAD version. It has no refinement and will only be able to do models when there size difference is not too large. I may work on it more in the future. I just want to test out some features and the software.

26th May 2017 edit: Updated the OpenSCAD with the "Flange" option as I'd have a couple of requests for something similar. Only use this one if size is really limited, the flow will be very inefficient.

12th February 2018 edit: Added a non-standard size on request. Very thin walls around the screw holes. Screw holes are undersized.

13th November 2018 edit: Added 40-20 on request. Undersized screw holes.

12th May 2019 edit: Added requested model.

2nd December 2019 edit: Added requested model.

10th January 2020 edit: Added requested model. 120-92 aligned at a corner.

25th June 2020 edit: Added 2 requested models.

6th July 2021 edit: Added requested model.

Contact me

Please feel free to contact me for alterations or custom jobs. Bear in mind I am usually busy with other things and only work on this item when I get the spare time.

If you have something very specialised and specific in mind please give me as much detail as possible in your request.