Arduino365 part 5: Modular Enclosure

15th February 2020

The usually overseen part of many arduino projects is the enclosure. So I have decided to devote some extra time to design and 3D print my own. I have no industrial design degree nor I am in the field doing it day in and day out. However here is what I have managed to come up with so far and what is the plan for the near future. The case has been designed for the Arduino Nano coupled up with the ENC28J60 ethernet shield and will be powered using Passive Power Over Ethernet. The general idea was to keep it all under wraps within limited space and use components / parts that are available for anyone to buy from Amazon / Ebay. Also no soldering or any of the usually hacking should be required either. You got the parts = you can assemble it.

Initially it all started with getting the bare bones up and running. I poked around the internet and found some designs that get the measurements right (yes I can be lazy) and build on top of that. My tool of choice is Tinkercad as it has all the functionality I would ever need to build a case. No need to go Fusion 360 on this project 🙂 Below the parts I have used and the 3D printed base that will be expanded on later as the project evolves and I get more ideas...

This really looked promising to me - I am sure you can agree. Next step was to create an outline and something that resembled a case that you could put things in instead of an open air holder (if that is a phrase). At this point I was not really bothered if I can close it with a lid - that was something to worry about later. So got the walls going, expanded the base and added few cutouts (for potential cable management) and here it is:

By now I have realised I need to get this design to be modular. As in certain parts of it can be just added on the fly to create whatever you need the enclosure to be. For example you might want a temperature sensor = you snap in an addon that has the proper layout for that. You require a relay = there is an addon for that. You get the idea. The core remains the same while you can customise the rest to meet your ever changing needs. On top of that I have added three mounting points (M3 screws) = now you know I mean business.

From here it all went out of control. I somehow managed to convince myself that this entire thing needs to become waterproof and dustproof. Took me some time to research and I discovered gaskets and things called o-rings. So... I have designed them into the enclosure. This does not just mean that I have added grooves and called it a day. Hell no! I had to redesign the thing to accommodate the extra required additions without increasing the actual dimensions of the case. I even got a snap-in module to seal off the ethernet cable - this will be done by hot glue (special compartment) and I also have an idea how to improve on the current design. I even ended up printing the lid this time. Behold!

The parts fit and everything is working out as I planned. But I was not happy with it somehow. The addon for the relay was bugging me. I scrapped it and designed a new module that would accommodate the DHT11 temperature and humidity sensor. I obviously applied what I have already learned about the grooves and gaskets... This is unfortunate the only best shot I have of it raw minutes after it has been printed. And finally... the whole thing programmed, wired together and assembled. Still lid-less, but you get the idea!

Now that looks like an enclosure for an Arduino if you ask me! If you are wondering why I decided to place the DHT11 inside the enclosure = I want to monitor the temperature and humidity inside the case when it is exposed to the elements aka outdoors 🙂 And the good news is that it has been already deployed for over 15 days and it refused to die for some reason. I have even tortured it by pouring water on it - like you would be watering plants. It has survived just fine. It also managed cold nights (relatively, it is humid here). I am talking about -1 degrees Celsius (I am based in UK, don't expect -20). The experiment so far was a good run. There are things I want to add and things that I want to improve. Last two shots: first six days graph of the data (I used an arduino data logger - every 5 minutes it sends a request for the up to date stats = the Arduino Nano has a web server running that responds to a certain command with data) and the enclosure mounted outside. There is room for improvement but for now I am pleased with the results.

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