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Various fan size conversion adapters.

by TheMeerkat, published

Various fan size conversion adapters. by TheMeerkat Apr 10, 2012
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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jobs made on request, the beta OpenSCAD file for the Customizer, an older version of the native SOLIDWORKS file and a newer version of the native Inventor file.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.

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.


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.


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

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.

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How is the 90-degree fan customized in SCAD? I cant seem to find the option.

I was hoping to make a 120mm-30mm converter @ 90 degrees

Comments deleted.

I was wondering if you could make me a 25mm to 30 mm adapter so I can mount a fang setup on my Prometheus hot end. Will definitely tip you if you could, Holes on 25mm fan are 20mm center to center with holes 24mm center to center on my fang mount.

Genius! Thank you so much

Just what I needed. Thanks!

can a Y adapter be made with this ?

Short answer, yeah.
Long answer: It depends on which sizes you want to use, then angle between the openings and the overall size of the adaptor.

How would I do that? I'm looking to adapt 2x 40mm fans to one 40mm fan in order to add more power to my tevo fang cooler. As compact as possible, overall size wise.

Thank you

Well these adaptors only convert sizes from a fan to an outlet. I have made a couple of adaptors for 2 into 1 (check near the bottom of the file list). If you would like I can make you a 2x40 into 40. If you give me any size limits, important geometric details and other important details your application has, I'll do it as soon as I get the spare time.

This openScad file is awesome and I used the customizer a about 5 times.
As mention in the description, It gives artefacts in the preview but it makes the model correctly and very fast. (1 minute to 4 minutes)

As a note from experiences from my 2 kinda failed adapters:
Measure your fan holes from the center of the screw holes.
I made some weird 35mm to 30mm and 40mm to 35mm adapters and I'll be using this to make my other fan adapters as well.

Anyway thank you for putting this file up, it really helped me out to reuse some of my small fans of my Asus Z77 Sabertooth motherboard.

Hey. Thanks for the comment. I'm glad that it is being useful.

Comments deleted.

Actually all 80 to x files are wrong. 80 to 50 is 80to40, 80 to 40 is 80to35, 80 to 60 is 80to50,

Please find a new image of the measurements of the four STL files in question.

These dimensions all are in accordance with those found in data sheets and are correct at least according to those datasheets. If you have a "non-standard" sized fan you can use the customiser to make one that fits or ask me to do a custom job for you.

Just wondering if you could remake a 120mm to 140mm with an offset so that one side lines up (one flat side - so that when two are placed together both sets of openings are adjacent) - the idea would be to be able to use 2 - to adapt 2 120mm fans to a watercooler with 2 140mm, or in reverse.

Did this model work for you? Which 2x 140mm fan cooler are you using? I will be using this to fit a Corsair H115i into my Cooler Master HAF 932 case which is designed for 2x 120mm fan rads not 2x 140mm.

Thanks for this request, saves me even more work but I am going to mod the file a tad to strengthen the 120mm mount boss.


Done. Please check sizing (particularly the 140 side) and spacing clearance before printing.
There is likely a need to do some sanding on this one.

Comments deleted.

Hi, I'm currently searching for a 80mm to 40mm design that is 75mm tall, and the top and bottom have to be offset, so that they share one vertical corner.

In other words, the 40mm fan mount is offset to the side.

I would do this myself but I do not have solid works. Could you please make one for me? I'd be willing to send you a fiver through paypal :)

Hey. Did you a quick one, hope it satisfies your needs.
Feel free to tip me if you feel I deserve it.

TheMeerkat -- I see this is a 2012 design so dating back to Thingiverse beginnings but still going brilliant!
Now I can use larger fans that are much quieter by an order of magnitude for the same CFM. I am printing the 80/40 right now.
It would also be awesome if a SCAD wiz converted this to Thingiverse Customizer.

Also, any commentary from anyone here on flow efficiency? I expect it to be a bit reduced but just curious if anyone noticed/measured.

I hope it worked out for you and proved useful.

As for the efficiency of flow, it should be quite reasonable, I have no figures though :)
The angle of taper is such that it should keep the disturbance in the airflow down as much as possible, but the larger the difference in conversion the worse they are likely to get.

50mm to 30mm is actually 50mm to 40mm.

50mm to 30mm is actually 50mm to 40mm.

I measured the holes in the model and STL and they were the right size, but the attachment hole spacing was wrong.

Also a request

i saw the nasty adapter and wondered if you could add a simple 90 angle adapter. going from 60mm to 40mm

found the right angle here: http://www.thingiverse.com/thing:215299

40mm-Fan 90° Bow
by Souko

Can you please update 60-50 without support?

i ask : why it not been make before ? it´s absolutely wonderful

Great work! Thank You!

I wonder wth would happen if i try to print them all and make them all fit together

Why draw it your self if its all ready there? Just great! needed this!

anyway you can make these thinner?

Yeah they could be thinner, but if they are too thin then they'll not be quite as effective at keeping the flow smooth and efficient.

Which ones are you wanting thinner and what is your thickness limit?

Just what i was looking for. Thank you for your work

Printed the 40-30v2 and the hole are too large for an M3 screw to thread into. Both sides are set as clearance holes? Like the design though.

I needed this, printed out great. Dimensions were spot on. Thank you.

I'm glad to hear that.

the 60to30 is actually a 60 to 40

Indeed, you're right. Thanks for that.

Comments deleted.

The 70 to 50 and 50 to 40 are both too big, I compared to other prints that i know have correct meshes and they are indeed to big, enough that half of the screw hole is offset on all sides. Suspect the scaling on others is off too. Have you checked your unit settings in your CAD program? They seem off.

Edit: I checked the dimensions in the part and they are fine and the dimensions in the STL and they are fine. I added 2 new pictures to the gallery showing the 70-50 and 50-40 adapters, as STL files, with their hole sizes dimensioned. I'm not seeing the problem you are talking about.

When I get some printing time I will have these 2 printed and update as to what I find there.


Thanks for your input. I've been a little busy with things recently but I will give them a looking over when I get the chance. I doubt it is my units, IMO it is most likely the conversion from native to STL that is causing the problem. The annoying thing is nobody else has reported problems :(

Anyway, thanks.

I had to scale down 5%

can you tell me the high of your adapters? (40-60 would be of interest) [high me meaning the distance from one fan to the other so i can add another 25mm of the fan to have a total]

60-40 is about 21 mm.

Can you please make one that is 200MM to Dual 80MM ?? I am trying to Mod http://www.thingiverse.com/thing:634403 to a single 100CFM 200MM fan I have Thank you in advance

Da Vinci 1.0 Fan Mount

So, you want to bolt a 200 to 2x80 to this Da Vinci thing? I will see what I can do when I get some spare time. Do you have any dimensional limits you want me to follow? Also, do you have a datasheet for the 200, I can't seem to find multiple sources using the same sizes so your specific model would have to be used.

Comments deleted.

Which one(s). As I said in the information, I have only ever printed one of these for myself. Others seem to mostly not have any problem though. So, as much as I appreciate the critique, I could use more information. I use design tables in the model, so corrections can be made in minutes with minimal effort.

Every dimension is taken from dimensioned drawings provided by fan manufacturers. The holes are usually, of course, a smaller distance between each other than the overall size of the fan, this is followed when creating each adapter. But mistakes can happen, so, please tell me which ones you are having trouble with.

What tools do you use to make these? I want to make something similar. I want to see about making a 2x 120mm to 180mm adapter that might fit in my case.

The geometry is created in Solidworks, however any comparable 3D modeller will be fine.

Could you do 140mm to 120mm and 180mm to 120mm :) Thanks

Done. Scruffy but should be OK.

Comments deleted.

can you make a 75 to 50 please?

I can't find dimensions for 75 mm fans. But there is a 70-50 adapter here, that should work.

Could you make a 70mm to 80mm adapter please?

There already is one.

Sweet! I must have missed it, thank you for you're work.

how about a 25mm to 30mm adapter? 25mm is the right size for a hexagon hot end, but 30mm fans are a lot cheaper and more common!

Done it very quick and dirty. Sorry I can't give any more time to drawing something more suitable up.

I got shipped an extruder kit with the wrong fan. This should let me make do. Much appreciated.

Nice work. I have printed a few of these and they look awsum.
Any chance you could add a 40 to 35 adapter the same as the 40_-_30_mm_v2.STL

I would be glad to but 35 mm isn't a fan size that is common. I need to know a few dimensions to do it properly. At least distance between mounting hole centres and hole size.

I thank you and my extruder thanks you :)

I love it when I need something and a quick search on Thingiverse and ... poof! There it is. Thanks

is it possible a 40 mm to 25 mm? cannot find a 25 mm fan! Thank you!

Done, hope it meets your expectations.

The 50 to 40 seems to have a hell of an overhang on the mounting holes with the smaller end. Any chance of a fix?

Sorry it took me so long, I've been busy with real life :v
Did the best I could.

Possible for a duel 80mm to single 120mm on an 90* angel so that the 120mm side is no higher than then 80mm

Sorry it took me so long, I've been busy with real life :v
Did a very quick and untested 2 x 80 to 120. I haven't run any flow simulations nor have I printed as I have no use for such a beast. Consequently I have no idea how the flows will mix or how it will work out.
If you print it do give us a report on its efficacy.

Your 50-30 is actually 50-40. any chance of getting a 50-30? thanks

Please can you made fixes an 40to30 ??

Sorry it took me so long, I've been busy with real life :v.
I have altered the mounting hole distances that were incorrect.

You can maybe use this http://www.thingiverse.com/thing:154779http://www.thingiverse.com/thi... instead, for 40to30.

Simple various sizes fan adaptors
by qvarker

Made fixes to 50 mm adapters and added a new iteration.
Now my download box isn't as uniform but they should all work.

Can you do an 80 to 40 one?

I had two companies print the 70to50 and 80to50 and the large side is perfectly aligned, but the 50mm side doesn't line up with the holes. I ended up using zipties but it would be cool to use screws!

The 50mm side is approx. 5 mm too large.

Seems the datasheet I used for 50 mm was for a cheapo unstandard one. It is now fixed.


can you make one
from 50mm to 40mm ?

Thank you

How do I turn them to be printable?

My printer software allowed me to do it, however I suppose you could use some other modelling software to rotate it. I think someone mentioned blender.