Cooler Fan: How

The fabrication process of my cooler fan went better than expected. I was able to get a good first 3D print, my measurements were nearly perfect, and I was able to complete all my tasks on time. Overall, the project went very well from the design process to fabricating. A few issues did come up, but the fan worked as expected and only a few cosmetic problems came up. 

New to the Left, Old to the Right

Timeline

Timing for this project almost lined up with the timeline I estimated initially. 3D printing was a bit delayed by ten days due to a longer than expected design time and needing to rework several problems found when planning to 3D print. I added eleven extra days to the timeline just in case of problems, and as I guessed, I used up those days. I forgot to add fabricating to the timeline but the time used fit well into the extra days I planned for. I ended up with several days in between completely assembling it to the project deadline. With those days, I used it to touch up minor cosmetic issues, and just to overall refine it.

Estimated and Actual Timeline

I was also a bit delayed figuring out dimensions for some test fits, specifically for the threads and lid, heat exchanger, and other minor parts. I wanted to print these test parts to verify I had the correct measurements.

Test Prints

Fabrication- 3D Printing/Waterjet

To start fabricating, I began with 3D printing the housing using the Idea Forge printers. I initially planned to use a SLS printer with nylon filament but I didn’t realize until quite far into the design stage that it would cost nearly $200 in nylon alone. I was already over $100 into fasteners, metals, and components, so I decided to cut corners here and just use PLA with a FDM printer. The housing was printed with very few defects, and the ones that were there are hidden from the exterior. In an ideal scenario, I would’ve really preferred to use the SLS printer to get better quality prints, but I’m still very happy with what I got. 

3D Printing Housing

The aluminum covers were water-jetted with Idea Forge’s water cutter. I used ⅛” thickness aluminum sheet for both covers. I simply put in a request and the staff there helped me. 

Fabrication- Assembly

I ordered most of my parts before fabricating because I needed to take measurements of each part. I was able to connect the heat exchanger and fan together before I finished printing the housing. The most noticeable part of my project is probably the insulated cooler, simply because it’s so large, and I did not make that. The one gallon insulated jug was purchased from Walmart and is an Ozark Trail brand. 

Insulated Cooler I used [1]

Once I had all my components and parts, I began to assemble it all together. I started with the housing that I print in 2 parts. I designed the housing in two because I wasn’t sure which printing technology I was going to use at first, and so I didn’t know the print bed size. I figured I would plan ahead of this possible issue and just split the part into two. I designed two holes through the parts to accommodate a bolt and nut. I found some cool low profile socket screws on McMaster-Carr that I used for this.

FDM Printed Housing

One of the more annoying parts of this process was inserting the hose for the water. I included channels in the housing to allow the hose to travel from the heat exchange to the pump and jug, but I used too tight of a tolerance. There is also a 90 degree bend that was difficult to navigate, but not impossible. With a little elbow grease I was able to get it in. At the same time I fished through several wires for the pump and fan. I included a hole through the channel to the “electronics enclosure” so the wires can connect to the plug and switch. I bought little rubber seals to prevent any possible water from entering into the electronics enclosure but I didn’t end up using them because the hole I made was too thick. I ended up buying silicone and filling the hole in.

I designed a cavity that I have been referring to as the electronics enclosure. This hole houses wires and accommodates the space needed for the switch and USB port. To cover it, I used an aluminum sheet with holes cut into to fit the switch and port.

Partially Complete Housing

Similar to the enclosure cover, I used the same material on the heat exchanger cover. I decided to not fasten the exchanger to the housing, and opted to clamp it between the housing and cover. The ports are aligned with the fan to allow airflow and I spent a good amount of time filing and sanding the corners smooth.

Heat Exchanger Cover, Front Cover

The electronics are pretty simple in this circuit. It’s essentially just 5V power entering a USB-C port, connected to a pump and fan in parallel. An on/off momentary switch is added in series to the power side of the USB port. I was able to find 5V pumps and fans so that simplified the circuit even further. I bought some Noctua fans because I figured I wanted as much airflow with their quieter fans, it’s funny because my PC doesn’t even have them. 

Electrical Enclosure and Components

Once everything was assembled into their own sub-assemblies, I just needed to fasten the covers to the housing. I used heated inserts to add threads into the plastic housing. This allowed me to use screws I found on McMaster. The screws are actually pretty cool, they are low-profile stainless steel socket head screws. Fun stuff. 

 

Final Product

With all the components made and parts assembled, I ended up with a final product!

I’m quite happy with how it all turned out, I was pretty nervous on the aesthetics while assembling. A few issues appeared, for example I designed the enclosure cover a bit too large. I went back and forth slowly grinding away the cover and the housing. I ended up grinding away too much plastic on the housing and there were very noticeable holes. I ended up melting PLA filament with a soldering iron to fill it in. The finish isn’t perfect, but it is definitely better than the holes. Another issue is the heated inserts; I’m not sure what exactly went wrong but some of the screws don’t sit perfectly flush. 

I tried to sand and polish the aluminum covers, but when I did a test run on some offcuts, my “polishing” was worse than the huge scuffs already on it. I decided to hold off on that and improve this certain skill until I make another attempt. If your really, really far, it looks pretty good!

The biggest improvement I would like to tackle later is the threaded cap. To seal the housing to the jug, I have to screw it on, which causes the hose inside to tangle and sometimes get cinched. I think if I were to completely revise this project, I would use a clamping mechanism to attach the housing to the jug. I want to eliminate the need to rotate the housing and just “plug” it in. 

 

If I do decide to implement these changes, I think I would actually use a SLS printer. Although it is pretty expensive, I think if I got to the point of wanting another version, it would be to sell it or something. Basically, the current one I made is good enough for personal use. 

Final Thoughts

The aesthetic I was aiming for was minimalism but combined with the look of ruggedness from other outdoor products. I also wanted to match the polished aluminum jug, so using metal for the covers added that rugged look. I have noticed it does look a bit industrial rather than minimal, but I think the principles of minimalism are there: simple lines and curves, minimal material use, and some would consider, void of character(but I think the metal fixes this problem compared to true minimalism).

Citations

[1] https://www.walmart.com/ip/Ozark-Trail-Stainless-Steel-1-Gallon-Water-Jug/285297047?wl13=5341&selectedSellerId=0