EdgeCase - The non-invasive, recirculating, internal HEPA and carbon filter for the Core One

This project upgrades your Core One with an internal recirculating HEPA and activated carbon filter. This is achieved without major modifications to your machine, as the filter fits into the left rear corner and mount directly onto the nylon rivets.

You can use either 4028 axial fans or 4020 blower fans, or even one of each if that is what you have available. The HEPA filter should be the one linked below or something equivalent in size. Make sure you use activated carbon suitable for 3D printers. To be safe, I recommend getting some made by the Nevermore team, such as the one below.

Features

- Filters chamber air without an exhaust. Good for maintaining high chamber temperatures.

- Mounts with the original nylon rivets without modifications to the stock enclosure. No invasive or permanent modifications are necessary.

- Both the HEPA filters and carbon pellets are housed in magnetically attached filter pods, which are easy to change anytime. It is necessary to remove the side panel only for the base unit installation, and then refills can be done without hassle.

- Prints without supports.

- There is no interference with the stock chamber fans / filter, so the cooling performance of the chamber is not compromised. The EdgeCase can be used either in addition to or instead of the advanced filtration system.

Print instructions

- Use a reasonably heat-resistant filament, at least for the base. I used ABS-CF (dirt cheap and heat-resistant) for the base and Prusament PETG for the filter pods. Possibly, PETG could be okay for everything, but I didn't test. Unfortunately, I ran out of Prusa Orange for the very final version :(

- The models are already oriented in the intended print direction, in which they will print without supports.

- Everything is dimensioned for a 0.4mm nozzle, and many walls are dimensioned exactly to yield the correct number of perimeters. A larger nozzle might result in weak spots, seam lines in unexpected places, or even holes. Don't underestimate how tightly the space was budgeted to make this happen!

Bill of materials

- HEPA filters, which must be 8 cm x 4 cm x 1.5 cm, such as these: (Aliexpress link)

- Fans, which can be either 4020 radial blowers or axial fans of size 4028 or 4020. I tested the 4020 turbo 24V radial fan from here: (Aliexpress link) and the 24V 4028 axial fan from here: (Aliexpress link) . I think the performance is very close, but perhaps the 4028 axial is a bit more powerful, although the 4020 radial is definitely quieter, so go with what you prioritize.

- Activated carbon, which must be acid-free to avoid damage to your printer. A reliable source is the activated carbon formulated by the folks at Nevermore. Find a reseller here: (Nevermore resellers)

- Mangets for attachment of the filter pods, which should be of size 6x2mm. You will need 28 magnets. I recommend these: (Aliexpress link)

- M3 screws to attach your fans to the base units:

- Two 4028 axial fans will require a total of eight M3x35 screws

- Two 4020 blower fans will require three M3x20mm screws and three M3x15mm screws.

- One M3 screw of any head type of 15mm or longer for joining the two base halves.

- Two countersunk M3x6 screw, such as these: (Amazon.it link)

- Wires to connect the fans to power.

- Optional: The Prusa GPIO hackerboard (see below)

How to wire the fans

Depending on your ambition, you can wire and connect the filter to your printer in different ways:

- The simplest option is to go for 2-wire 24V DC fans, which you can power by simply running a wire to your printer's main PSU. In this way, the filter will run whenever your printer is powered on.

- To gain more control, you can connect the filter through the Prusa GPIO hackerboard. The Hackerboard can act as a relay for the 24V DC power of the main PSU and you can thus control the filter fans from gcode. This way, the filter runs only when you have an active print.

- You can house the hackerboard next to the wifi module, for which purpose I made this remix: (link to GPIO mount).

- To control the fans with the hacker board, go to the Printers tab in PrusaSlicer, go to Custom G-code and add the following to your start gcode:

; ------------------------------------------ ; Enable EdgeCase fans M262 P0 B0 ; Set pin 0 as an output pin M262 P1 B0 ; Set pin 1 as an output pin M264 P0 B1 ; Set pin 0 to on, enabling the bottom fan M264 P1 B1 ; Set pin 1 to on, enabling the top fan ; ------------------------------------------ And the following to your end gcode:

; ------------------------------------------

; turn off EdgeCase fans

M264 P0 B0 ; Set pin 0 to off, disabling the bottom fan

M264 P1 B0 ; Set pin 1 to off, disabling the top fan

; ------------------------------------------

- If you get 24VDC 4-wire PWM fans, then you can also control the fans using the xBuddy board directly. I have not done this myself, but I see two scenarios in which this can work:

- If you do not also have the Advanced Filtration System installed, then you can use the Fan3 port intended for the filter fan. I know other similar projects (for example, this one ) do this, so this is known to work.

- If you also have the Advanced Filtration System installed, and you are willing to give up the chamber fans, which are then disabled by default, then you might be able to recycle those connectors. However, I'm not sure if the firmware play along with this, so do you own research if you want to pursue this. And make sure to give feedback here if you try!

I would like to keep both my Advanced Filtration System (to provide slight negative pressure) and the chamber fans (to boost PLA/PETG/TPU chamber cooling), so I went with option 2, 2-wire 24VDC fans and the Hackerboard. But, you do you!