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Cooling LEDs using fans

It’s quite hot in summer and the temperature in the aquarium goes up to 30 °C. At the same time, the LED light cooling is worse. It influences the light intensity and LEDs' degradation.

Some time ago, I bought a tiny fan of 15 x 15 mm which I fastened using silicone inside the aluminium profile. The profile’s dimensions are 40 x 20 mm; the aluminium thickness is 2 mm. It means, the inner dimensions are 36 x 16 mm. This fan is very tiny and was not cheap – approx. US$ 7 on eBay. It is not very efficient for cooling of such power.

I started contemplating the 25 x 25 mm fans that are significantly cheaper. The problem was how to fix them on the aluminium profiles. I had an idea of creating my own fixation components on the 3D printer. So, I had to learn designing mechanical parts in the DesignSpark Mechanical application.

The first prototype didn’t work out very well because I hadn’t activated the support materials option in the printing settings. I also made the model too accurate. It was necessary to remove 0.1 mm at each side to be able to plug it into the aluminium profile. Moreover, I had found wrong data for the outer dimensions of the nut. I left there 4 mm hexagons for them; the right size is 5 mm. So, to verify the second prototype’s functionality, I had to file the nuts to reduce their size to 4 mm. Finally, I managed to fabricate the latest components with the right features.

I made a little cover for one side of the fan to avoid contact with the propeller and an air duct, for the other side. The fan is mounted on an air duct’s side. And the other side of the air duct is plugged into the profile. I mounted the cover, fan and air duct using the screws of 2,5 mm with the length of 20 mm.

Another problem I had to solve was space in the aquarium. The gap between the profile and the original fluorescent lamp holder was only 17 mm. The module needed at least 25 mm. I decided to create a narrower lid on the 3D printer to replace the original holder. To do so I had to measure the holder and its thread. Again, I didn’t manage to screw the first prototypes. They were too accurate. Finally, I changed the parameters to have some tolerances and I successfully screwed the part. The gap got enlarged to more than 30 mm.

Finally, I mounted the fans on the aluminium profiles and closed the aquarium hood without any problem. The whole procedure is documented in my video.

In terms of the fans, on eBay I ordered some alternatives for testing:

  • 17000 RPM with the thickness of 10 mm, ball bearing. The price US$ 5. The airflow is good but due to high noise I didn’t use it in the end.
  • 10000 RPM with the thickness of 7 mm. The price US$ 3. The airflow is smaller but it is silent. I used it for a shorter profile.
  • 11000 RPM with the thickness of 10 mm. The price US$ 2.70. I haven't yet received it.


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