Advanced Filtration System Exhaust for Original Prusa Mini Enclosure

Features

• Closed door printing PLA/PETG with controlled temps.
• Negative Air Pressure Full filtration 94-96% efficiency
• Recycle or Vent airflow
• Redirected airflow with no bed drafts
• Snap together construction

Purpose

The whole point of this mod is to create a negative pressure state inside the enclosure so that all fumes and particles from the printing process stay inside the enclosure and exit through the filtration system. According to the Prusa published specs this means 94-96% of all fumes and particles will be captured by the filtration system before the air is vented externally.

I was not a fan of the internal air recycling system of the original design. I felt it did not do a great job with capturing fumes and took longer to clean all the air inside the enclosure. Additionally the original Filter Bracket design had the fan unit pointing down which introduced a draft towards the build area.

After testing with a few 6-12hr prints I've found the temp inside the case stays at about 1-3C higher than the ambient with the door closed. This has meant for me that PLA/PETG prints don't run into issues.

Printer Settings

• Print settings : Default 0.20mm STRUCTURAL
• Printer : Original Prusa Mini+ Input Shaper 0.4 nozzle
• Filament : Generic PETG
• Perimeters : 3
• Support : Painted On
• Brim : None
• Infill : 15%

Assembly Instructions

This upgrade requires a few steps to complete, but it is fairly straightforward.

Before beginning assembly I strongly recommend test fitting each part together. They should easily snap together.

1. Disconnect and remove the Prusa Mini+ from the enclosure if present. 
2. Carefully uninstall the existing fan/filter assembly. NOTE: You do not need to completely uninstall the fan to complete these steps. You should be able to disassemble/reassemble inside the enclosure.
3. Remove the rear plexiglass panel by popping all the plastic plugs out, and possibly the power adapter bracket if you have that installed.
4. Remove the filter and the fan from the existing Filter/Fan Bracket.
5. Install the Fan and Filter into the new Filter/Fan Bracket.
6. Cut out the octagon plug from the plexiglass panel and file down any points created from removing the octagon so that all eight sides of the opening are flat/flush.
7. Install the exhaust bracket halves onto the plexiglass panel by either snapping or screwing them together. NOTE: The plexiglass panel will be installed with opening towards the top of the case! This is important to note when orienting the brackets. 
   1. The exterior bracket half should be oriented with the flange towards the top.
   2. The interior bracket half should be oriented with the slightly thicker flange towards the top as well.
8. Reinstall the plexiglass panel so the octagon hole with brackets is oriented at the top.
9. Reinstall the Fan/Filter Bracket Assembly.
10. Reinstall the power adapter bracket if it was removed.
11. Insert the Airflow Direction Selector into the Selector Body and ensure it is seated properly.
12. Gently snap the assembled Airflow Direction Selector onto the Fan/Filter Bracket Assembly. 
13. Gently snap the Airflow Direction Selector onto the back plexiglass panel Vent Bracket. NOTE: You will likely need to push on both sides of the panel to get it to click in place easily.
14. Reinstall the Prusa Mini+ printer into the enclosure.
15. Gummy Bear Time!

Acknowledgement

I attribute all time, skill, and effort to the original authors DaHouzKat and Vespercorp. Be sure to check out their stuff. 

DaHouzKat and I worked together on this remix. DaHouzKat did all of the new ducting parts, and I modified the Filtration Assembly Housing as well as all of the practical printing and testing of parts.