Core One Recirculating Advanced Air Filtration System

This is a recirculating air filtration system for the Prusa Core One printer.  This system draws air into the filter from one of the Core One's enclosure fan openings, and exhausts it back into the enclosure through the other fan opening.  This method recirculates the warm enclosure air inside the enclosure instead of exhausting it into the room.  Filtration systems that exhaust the filtered air out to the room results in cooler air being drawn into the enclosure due to negative chamber pressure when the filter is in operation.  This can impact your printing of materials like ASA that like a warm ambient temperature during printing.    

Additionally, this design utilizes a sliding bracket to drop the filter housing down out of the way of the Core One's internal exhaust fans when printing materials that do not benefit from from a warm enclosure.  Just flip open the latch on each side of the slide bracket and slide the housing down to a stored position.  This clears the Core One's internal fan openings.  If the filter is not in use, the Advanced Filtration setting in the firmware should be disabled to hand back chamber venting control to the internal exhaust fans. 

After printing the slide bracket you will need to work the latches free.   Due to some tight tolerances they may be a little stuck together after printing.   Easing them back and forth a bit broke them loose in my case.  Then the slide bracket needs to be glued to the slide bracket frame with some CA glue.  To aid in alignment there is a slight indention in the slide bracket frame where the slide bracket sits.  The tolerances are pretty tight so you will want to wipe away any glue that may gather on the inside corners so that the filter housing will slide freely in the frame.  Go lightly with the CA glue.

You will need (4) M3x6 cap screws for attaching the slide bracket frame to the printer, and (4) M3x8 or M3x6 cap screws for screwing the lid to the housing.  Don't over tighten the screws when you are attaching the lid to the filter housing or you'll strip the holes in the filter housing.  Follow the Prusa instructions for the Core One Advanced Filtration installation to connect the filtration fan to the motherboard here: https://help.prusa3d.com/guide/how-to-install-advanced-filtration-core-one_868297#869006.   The fan sits in the bottom of the housing.  In my original design the HEPA filter gets pressed directly down onto the fan, carbon side against the fan. However, I updated the design to have a separator between the fan and the filter.  The fan presses tightly into the bottom of the housing and does not require further attachment.  Then insert the separator--check to make sure the hole in the separator is properly aligned with the hole on the fan face--it has one correct orientation.  Then press the HEPA filter down into the box, carbon side towards the fan.  Install the cover and you're good to go!

This system utilizes the Blurolls fan and filter assembly found here:  https://www.blurolls3d.com/products/blurolls-hepa-13-air-filter-for-prusa-core-one-3d-printer-filtration-with-activated-carbon-fan-dust-odor-eliminator?VariantsId=11074.   \

Note: the filtration setting in the printer settings should be set to "Advanced Filtration" when the filter is in use.   In the chamber filtration settings you can also bump up the fan speed to 60% or whatever you want since the system recirculates and does not draw cold air into the chamber.  The factory setting is 40%.  Additionally, in the filtration settings, there is an option for "Filter all Materials" that I leave on since the filtration is only in place for materials that need it.  When you drop the filter back down when you are printing materials that don't require filtration, set the chamber filtration back to "None" to hand temperature control back to the internal fans.

I printed it with PLA, .4 nozzle with .15mm layer thickness.