2.85mm Filament Geared Bowden Extruder Feeder

(Deutsche Version) As promised, I will now explain all the single parts of my multi-material Ultimaker. Today, I will explain the feeder. Unfortunately, I did not find a good solution, so I had to build my own feeder. The feeder consists of several 3D printed parts.

The following parts are required for the extruder:

• 3D printed parts: https://www.thingiverse.com/thing:3703063
• Several parts from ebay or other shops (I suggest using the pictures below to buy the correct parts)
• A 1.75 mm metal feeder ("MK8 Metal Bowden Extruder" on ebay)
• A 4/6 mm bowden tube (PTFE, inner diameter 4 mm, outer diameter 6 mm)
• A bowden coupler (comparable to the original part at the Ultimaker 2+, "Bowden tube clip" on ebay)
• Extruder gear
• 2 x 26 teeth extruder gear
• 2 x bearings 625ZZ (16x5x5 mm)
• Nema17 motor, 1.7A, 0.9°
• Screws
• 3 x M3x10
• 3 x M3x30 (longer screws would be better, e.g. 35 mm length)
• M4x30
• Aluminum rod, 5mm diameter (I only found 5.3 mm, this is also fine)

At first, the motor is fixed on the main part.

Next, the feeder has to be adapted for 2.85 mm, therefore a 5 mm drill is used. Then the edges are rounded a bit.

Afterwards, the screw that holds the spring has to be shortened, otherwise the two screws will touch before the spring can build up enough pressure.

The next step is mounting the bowden coupler and bowden tube to the main part.

Now, the feeder is mounted with a M3x10 screw to the main part, from the other side a bearing is placed in the designated holder and both things are fixed with this screw. Important: The head of the screw has to be inside the metal part, otherwise, there could occur problems later.

Then, the arm of the feeder is built up (here you need the M4 screw) and mounted, therefore the three M3x30 screws are mounted in the other direction as the M3x10 screw. Afterwards, the spring is placed in the arm.

Now you need a 52 mm long piece of the aluminum rod. Mount the extruder gear with 7 mm distance to one end.

The large sleeve is placed on the rod, then the rod is placed into the bearing. You might need to push the arm a bit so it fits well.

If you fixed the M3x30 screws with nuts, you should remove them now. The second bearing is placed on the axis and the suitable holder is placed on top. You can fix this with the lower screw by placing the nut there, if you increase the pressure from the string with the M4 screw, the other screws will not fall out any more.

Afterwards, the large black clip is mounted, after this you can add the final two nuts to hold everything together.

Now we go to the other side of the extruder. The two extruder gears with 26 teeth are mounted in the big gears, you can use a small drop of glue to prevent them from sliding apart. The small sleeve is placed on the rod, otherwise the big gear will grind on the holder for the bearing and start to melt together. The gears are now mounted on the rod respectively the axis of the motor. Use some pressure from below on the axis to fix everything tight together.

Your extruder is now completed and can be used. Of course, you can use this extruder for any 3D printing issue that is not linked to multi material printing.

If I did not explain everything precisely or if I forgot to mention something or some material you need, please tell me so I can add this to this post.

Fully automatic multi-colour printing with the Ultimaker 2+

(Deutsche Version) As descirbed in my last post last november, I tackeled the topic of doing multi-colour printing with my Ultimaker 2+. Now, after several months I figured out a solution how to print multi-colour objects with an Ultimaker 2+. In this post, I want to describe the different components and then upload a post for every single component.

The basic principle is similar to my semi-automatic multi-colour printing, instead of having multiple nozzles like the Ultimaker 3, I onle use one nozzle and for every material change, the material gets pulled out and the next material is inserted into the nozzle. Therefore, I attached a Y-splitter behind the extruder to combine multiple bowden tubes. At the end of each bowden tube there is a filament feeder, meaning that for every colour I want to print simultaneously, I have to build up an own feeder. During the retraction of the material, the printer codes the next needed extruder in the movement so an external electronic can distinguish which motor has to be switched on next and then switches to this motor via a relais card. The whole project consists of the following parts:

1. Y-splitter for the bowden tubes
2. Multiple feeders
3. External electronics to swich the extruders
4. Scripts in Slic3r

The first thing is solved quite easily, therefore I created designs for 4, 8 and 16 bowden tubes and uploaded them to thingiverse. You probably have to tune the printing properties (horizontal expansion) so the adaptors fit.
https://www.thingiverse.com/thing:3695457