What happens when an air filter for 3D printers gets designed by engineers with a passion for function, a refusal to compromise, and a desire to do without bad smells or fumes? You get the Nevermore, a design for a recirculating active-carbon filtration system to deal with VOCs (volatile organic compounds) from 3D printing.
The Nevermore Micro (and larger Nevermore Max) were originally intended to complement the Voron 3D printer design, but are made such that they can be used with just about anything else. These filters use 3D-printable parts, and are designed to be easily filled (and refilled) using bulk-activated carbon instead of some kind of proprietary pre-packed filter like most commercial offerings. The Voron project is all about a printer without compromises, and the Nevermore comes from that same design ethos.
A Nevermore filter sits inside the build chamber, and works by recirculating air inside while passing it through the activated carbon. The idea is that by concentrating on dealing with the problem at the source inside a relatively small build chamber, one doesn’t need a lot of airflow. A small recirculating air filter can do the job efficiently, though for best results, the build chamber should be as sealed as possible.
One interesting caution is that it seems not all activated carbon is the same, and it is absolutely crucial to use only acid-free, steam-activated (not acid-washed) carbon in a recirculating filter like the Nevermore. There are horrifying photos of oxidized metal surfaces resulting from using acid-residue carbon, some of which took only minutes to occur. Thankfully, there are pointers to trusted sources for the known-good stuff.
It’s known that 3D printing results in chemical and particle emissions. These differ significantly depending on both material and type of printer, but it’s enough of an issue to warrant attention. One deals with particulates with something like a HEPA filter, but VOCs require a carbon filter. This is where the Nevermore comes in. Active carbon filters will wear out simply from exposure to the air, so if one is serious about cleaning VOCs when printing, it is definitely worth looking into bulk carbon with a design like the Nevermore.