Before designing the box, we wanted to create some legs on which the board could comfortably sit without rocking. As such, we decided that creating some friction fit, 3D printed standoffs would be the way to go. To do this, we measured the available space around the holes on both the Galileo Gen2 and the PCB for the sensors where the standoffs could be attached. Using a free, online 3D design software called TinkerCAD, I generated a 3D model of the standoffs which we then took to the smaller 3D printers at the CUC Fab Lab to create using ABS plastic.
The first version of the standoffs did not have a long enough center column attached to the cap to hold the cap and stems together while having the board between them. They also seemed too thin to properly balance the boards. These issues were corrected with version two but there were still some issues with the design. Since the 3D printers are not incredibly precise, the caps and stems varied enough in size where a significant amount of sanding was needed to get them to fit together. In version three, I widened the outer diameter of the hole within the stem in order to accommodate for the error in printing size. This turned out to be too large and, even after slightly adjusting the diameter and printing additional models, it proved too difficult to account for the amount of error and warping from heating and cooling the ABS plastic. We managed to create a few good ones that would work for what we needed them to, but any attempt at creating larger quantities of standoffs was not feasible. The thinner standoffs were still needed for the PCB as the holes on the PCB did not have enough room for a larger standoff. In the future, we would create a few thinner standoffs with a longer center column on the cap and improve the fit of the larger standoffs.
Once the standoffs were created, we took measurements from the heights of the boards and determined approximately how large we wanted a box. The box needed to comfortably fit both boards and hold them in place in addition to holes in the side to allow for airflow over the sensors. As such, we placed the boards beside each other in the desired configuration and measured the size of all the ports on the Galileo, how large the holes would need to be on the side of the box for antenna mounts, and the size of the photo and UV sensors that would be flush mounted into the lid of the box. To add a little flair to the box, we decided to make the final version out of clear acrylic, similar to the box for the AirPi, and to add our own logo onto the lid.
Using the pressfit box cut path generator at the Fab Lab, I created a basic layout for the box and then added the holes in the sides and lid of the box approximately where they would line up based on the measurements taken. Once I was satisfied with the alignment of everything, I would take the PDF file over to the EPILOG laser cutter to cut the prototypes out. Since acrylic isn’t a very cheap material to cut with, all the prototypes were made with 1/8″ thick birch wood sheets since they cost less and would allow me to check for alignment and changes between each version of the box. After creating a prototype of the box, I would mark on the box where any changes were needed and adjust the cutpath file accordingly in a program called Inkscape. After three birch box version, voila! I managed to create one that was good enough to transfer over to acrylic. I’ve got to say, going with the clear acrylic does make quite the snazzy box.
Despite the nice appearance and fit of our current acrylic box, some minor design changes are still needed that we have not been able to achieve within the time allotted for the class. The holes to allow for airflow must be lengthened so air can pass over another sensor. The holes that fit the USB, ethernet, and other ports could also be more snug against the board to prevent shifting as well as an inside support to hold the Galileo still since it is significantly less wide than the PCB. Lastly, the inside lip at the top of the box also needs to be sanded to allow for the box to fully hinge open. If we manage to make another clear acrylic casing for the AirGalileo, we would address these issues so that the boards are held firmly in place and so cables can be easily removed or attached to the Galileo.
Weatherproofing and Future Design
Since the final version of the AirGalileo would be a miniature weather station, discussion of applications and placement outdoors came up when talking about design. When creating a weather proof design for the boxes, I had to think of something that would completely cover the acrylic box we had just made and would prevent water and debris from getting inside as well as methods of holding the weatherproof case in place. What resulted from thinking about these factors were two rather funny designed as modeled below in TinkerCAD.
The first box- the brown one in the image below- features a curved lid for water runoff. The curved, outer surface would be a hinged lid that could be easily lifted to provide access to the boards and any power sources or cables inside. The S-shaped lid would overlap the sides and cover any exposed cables and holes in the side of the acrylic box leaving only a small over hole through which air can pass through to the sensors. In order to keep debris out and reduce the odds of water getting in, a small micromesh would be placed over these air holes to catch anything. The entire thing would be wall mounted or attached to trees. After designing the model in TinkerCAD, I realize the thing resembles a bird’s head coming out of a wall. As to whether that’s a cool design or not, I really have no idea.
The second weatherproof box concept I thought up would be something that rests on a flat surface or contains ground spikes to hold the station in place. Back to ideas for water runoff, a dome shaped lid atop a cylindrical container came to mind. Fairly simple overall; the dome lid would snap into place over the box and would create a complete seal to prevent water from getting in. Again, micromesh would be placed over the air holes to stop any debris. In the midst of modeling the actual container, I realized that it was pretty much a turtle. Yes, a turtle. By adding some legs to the box, it looked exactly like one and would have the perfect means for staying in place. Honestly, I think a turtle sitting on someone’s lawn and collecting weather data is a fun idea and would also double as decoration. Much better than a lawn gnome in my opinion.
Both these designs could be used indoor and outdoor but what we would really want for a weatherproof station is still up for debate. Again, these were some quick ideas off the top of my head and are kind of odd in form, but I really do find the idea of a weather turtle quite fun. There’s also the possibility of adding extra sensors and features in the future, such as a solar panel, battery pack, an anemometer, or a rain gauge, so nothing is really final. What we do know is that depending on what is added down the road, the final weather station should handle practically any weather thrown at it. Until that’s decided, I might just try making a lawn turtle of my own.