HEPA Filter for 3D Printer by jmillerfo

Last crawled date: 3 years ago

Air Scrubber for 3D Printers
The Prusa i3 MK2S is a great printer especially for the hobbyist or light industrial desktop user. That having been said it is a raw printer without a lot of accessories that would make it a great printer. The is the first in a series of accessories that I designed for the i3. The others are:
Enclosurehttps://www.thingiverse.com/thing:2396990
Spool Holderhttps://www.thingiverse.com/thing:2398480
OctoPrint Print Serverhttps://www.thingiverse.com/thing:2401423
This accessory is intended to remove VOC and Ultra Fine particles from the enclosure housing the printer.
3D Printers produce VOC and Ultra Fine particles as a unwanted byproduct of melting and extruding plastics. See recent study by Illinois Institute of Technology and The University of Texas at Austin among others: http://pubs.acs.org/doi/full/10.1021/acs.est.5b04983
Additionally some filaments emit a noxious odor when heated to high temperatures.
Originally the plan was to exhaust 100% of the filtered air either inside the enclosure (moisture elimination & heat retention) or outside the enclosure if internal ambient temperature was not a concern. The exhaust configuration could be changed prior to each print. After several experiments it was determined that a portion of the filtered air (about 40%) should be recirculated and the remainder ported outside the enclosure. By porting a portion of the filtered air outside the enclosure, the pressure inside the enclose is lower compared to ambient. This insures that no unfiltered air escapes from the enclosure during printing. The current Nozzle design accomplishes this. Included is a Restrictor plate to change the mix to 50/50% should the 40/60% cause the enclosure temperature to drop too much when printing ABS or other filament types that require a high stabilized temperature.
The design includes a Extended Grate that can be used to divide the chamber into two sections, one for silica (drying) and one for activated carbon pellets (VOC filtering). In practice it was found that the Activated Carbon Pellets provided adequate anhydrous characteristics and silica was not needed. Should your experience vary, simply insert the Expanded Grate at an appropriate location in the chamber. Fill the section closest to the Fan with Activated Carbon Pellets and the other with Silica. This insures all the air is filtered for VOCs.
This assembly is based on a design by RJ_Make that incorporates a HEPA filter originally designed for iRobot sweepers and a chamber which contains Activated Carbon Pellets. This remix differs from the one by RJ_Make:
Screws replace rubber bands to hold the various parts together,
Part count reduced by combining several parts into one,
Fan exit Nozzle has two outputs - One for overboard and one to recirculate filtered air within the enclosure,
Adds Exhaust Tube from Nozzle to Enclosure Grommet,
Includes Enclosure Grommet and optional Restrictor,
Specification for Fan and optional Speed Controller.
7/12/2017 Update: Removed file "Chamber Top" as it is no longer needed.
1/7/2018 Update:
Restore chamber Baffle,
Modify Chamber to capture the Baffle below filter flange in order to create space between Filter and Baffle,
Modify Filter to Motor and Expanded Grate by eliminating top several rows of holes to force more air to pass through activated carbon pile,
Support for alternative Fans.
3/5/2019 Update:
Added Strengthened Mount courtesy of beikeland.