Fitting a Bento air filter to a Qidi ifast 3D printer

Hopefully less tickly throat and itchy eyes?

For some time I have been subjectively conscious of fumes created by my 3D printers.   There has been quite a lot of general comment about this problem in the technical press.  I mostly use PLA for my prints using my Qidi ifast and Sindoh 3DWOX.  If you believe the press, PLA is the least likely to cause irritation.  However, my office is small and the printers are both close to my desk so any fumes are likely to be immediately adjacent to my computer activity.   If I do a long print run, I can sense the fumes as a background smell and as an irritation to my throat.

The geography of my office and workshop are such that moving the printers is not an option nor is finding some way to vent to the outside world.   The Qidi ifast is a huge machine and finding a new home for it would be difficult.   Transferring both machines into the workshop would expose them to a residual albeit low level of moisture (nothing rusts in the workshop so it can’t be so bad).

I came across the Bento filter unit which is a free download from Printables.   As an aside Voxel in the US sell Bento kits.

The concept of the design is to house a complete filter unit inside the printer chamber where it acts as a recirculating air filter (a ‘scrubber’). This only acts on the air circulating within the chamber.   This should avoid creating cooling drafts across the print job which might be the case if high volumes of air were being ventilated in and out externally.

The unit is visually shown opposite. It has four sections all stacked one on top of the other.  The air in the printer chamber enters the top section which contains a commercially available HEPA filter cartridge.  The next section is a carbon filter.  This has an inner printed magazine containing carbon pellets. The fan section is next with two fans pulling the air through the two filter sections.  The bottom section is the air exhaust duct. The design is rather well conceived with each of the two filter sections clipped together using small magnets.  This makes these two sections easily demountable for filter maintenance.  The fan tray and exhaust duct are held together with screws and brass inserts that pick up on the fan mounting holes.  

Circulating the air into the unit via the top section and exhausting at the bottom is a nice idea. In the Qidi ifast the print head stays at a constant height and the print bed moves down as the print builds.  The print head activity remains at a constant height to the filter input.  There is a lot of web discussion on fitting the Bento to Bambu Labs units but little about use in other printers so some head scratching was needed on how I might implement the Qidi ifast installation..

Here is a link to ZIP file containing my write up of how I installed the filter in my Qidi ifast together with the STL files for the modified fan tray, exhaust duct and microswitch mounting block.

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