Filaments and Prusa Buffer MMU3 in Prusa Enclosure with MK4

October 2, 2024 - Modification Spool Holder 1 and 2  for MK4S

With the arrival of the modified extruder in the MK4S, there was a problem that the new fan could hit the spools 1 and 2 on the right side. I solved the problem by modifying the spool holder, which can be found in the folder "Spool Holder for MK4S".

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May 26, 2024

In the COBRA System for Original Prusa Enclosure project there is an interesting idea of placing coils with filament directly in the Prusa Enclosure. This not only saves space, but the filaments are also protected from higher humidity.

After delivery of the Original Prusa MMU3, I decided to install the spool holders and filament guides in the Prusa Enclosure with the MK4 printer according to the COBRA project. For Buffer Cobra however there is not here enough space. After assembling the Prusa Buffer, I found in the place of the original power supply that there is enough space for this Prusa Buffer in the enclosure even with the Advanced Filtration System installed.

So that it was not necessary to drill new holes in the Encloure, I chose a magnet system for fixing the Buffer. To assemble the Prusa Buffer, it is therefore necessary to use several modified printed parts and 9 pc neodymium magnets 13x7x3 mm:

1 pc segmenter-240504
1 pc leg-240504
1 pc buffer-holder-240504 + 3 pc neodymium magnet 13x7x3 mm
2 pc plate-holder_1-240504 + 4 pc neodymium magnet 13x7x3 mm
1 pc plate-holder_2-240504 + 2 pc neodymium magnet 13x7x3 mm
2 pc of original unmodified "plate-holder-R3" 

Place the Leg part as shown. It increases the stability of the buffer by inserting its protrusions into the frame with molded polygons.

The PTFE tubes 4x2.5x650 mm supplied with the MMU3 can be used for the connection between the Buffer Cartridge and the MMU3. To guide the filament between the coils and the Buffer Catrige, it is necessary to purchase approx. 5 m of PTFE tubes 4x2.5 mm and cut them to these lengths: 
for Filament 1 - 86 cm
for Filament 2 - 65.5 cm
for Filament 3 - 98 cm
for Filament 4 - 119, cm
for Filament 5 - 97 cm

It is really important to use tubes with an inner diameter of 2.5 mm. For better guidance of the PTFE tubes, it is advisable to use the modified part "side-giude-240504", Press the M3 nut into it and fix it to the upper frame using the M3 x 10 screw as shown in the picture.

I used other guide elements and coil holders unchanged according to the Cobra project.

After assembling them, place the assembled Buffer in the Enclosure so that the protrusions of the Leg part fit into the gaps of the polygons in the main frame.

Remove any spikes from the PTFE tubes and you can bevel the inner edge with a drill, for example. This will help with the insertion of the filaments.

Route the PTFE tubing from the coils to the cartridges and also from the cartridges to the MMU3. Use the largest possible radii in the folds. Insert a sufficient length of filament into each guide and see if the filament can move freely - slight friction is not a problem.

In the Multicolor STL folder, files for color printing are also prepared for Buffer.

Filament guide parts can be easily colored in PrusaSlicer - see folder MF3.

The entire assembly works without problems for more than 100 printing hours. In the future, I plan to solve the cartridge holders removed from the buffer when inserting the filament.

The additional White LED Strip in the front left corner is now shadowed by coils Nr. 3 and 4. I'm going to fix this shortcoming, but I'd appreciate it if someone comes up with an elegant solution.

Finally, I have to thank @LudvigBroome for the great inspiration from the Cobra project.

Modified Segmenter, Leg, Buffer Holder and Plate Holder parts to accommodate MMU3 Buffer in Prusa Enclosure with Prusa MK4