V2 - In my mind, there were two areas that obviously needed improvement: 1) airflow and 2) electronics. I tackled both of these in parallel, which I later realized was important, as the things I was learning in one subject directly translated to a shift in strategy in the other area. I’ll explain more below.

I never took a fluids class in college, but if I did, I’d imagine this concept is taught on day 1: if I wanted to increase airflow velocity, I would need to either increase the fan speed, or decrease the cross-sectional area of the duct. I found a bend-and-stay duct that would be perfect for this application on McMaster, along with the accompanying rubber fittings. This was a nice solution because it allowed me to move the intake to the right position without needing to move the whole fan rig.

I chose to ramp up the fan by choosing a more powerful 12v Noctua fan, specifically the NF-F12 iPPC 3000. Being a four pin fan, you can actually controller the fan speed, but after reading the spec sheet, I discovered that leaving this pin disconnected would just make the fan spin at full speed, which is perfectly fine for this application. And considering this is now a 120x120mm fan, I needed to redesign the housing for all of this. There were several new modeling tools I used for this rev. One was the pattern tool, allowing me to replicate a hexoganal shape on the outflow vent in the back. This was really just to hold everything in place. I also got to play around with the loft tool. I used this in the previous prototype, but this model used this much more extensively allowing me to experiment with different loft types and features. It became immediately apparent that these are crucial to a modelers arsenal.

At this point, aside from connecting more batteries to this 12v fan, I needed to identify a better solution. There were a handful of DIY fume extractor guides out there, and I was able to learn a lot from them. Additionally, I learned a lot from a coworker about LiPo battery charging and using batteries for powering electronics. These lead me to realize that I needed a battery management device, and a low voltage boost converter. The concepts of each of them seemed fairly straightforward; the BMS would safely handle battery charging, while the boost converter converted the 3.7v output of the LiPo to the correct 12v needed for the fan. After a couple of youtube videos, I settled on a Sparkfun Battery Babysitter and an Anmbest Mini Boost Module. Both of these need a small bit of configuration to get started, such as setting the output on the boost converter to 12v by soldering some on-board pads, but nothing too crazy.

There were a few things I skipped out on during modeling this prototype, but I’m going to justify that by saying it was easier to print, and I was more of a functional test more than anything else. But upon putting it all together, I’d say conceptually, it worked alright. The shortcuts were very apparent though. I didn’t realize it when I started this design, but it became apparent quite quickly that this could not hold itself upright due to the weight of the bend-and-stay ducting. There was also a sizable gap between the filter and the fan that could be lessened. But perhaps most importantly, the suction power of the fan worked quite well! The duct needed to be about 6 inches away from the solder joint to be effective, which was far enough for it to be out of the way during use.