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Direct granules extruder version 3

My application video for the Shuttleworth Foundation gives a first look on how the extruder V3 works.


The Shuttleworth Foundation (shuttleworthfoundation.org) supports open source projects. Anyone with appropriate ideas can apply.

The second video shows details of the construction


The Third video tells a bit more about the evolution of the design


The fourth video is for the final round of the Hackaday Prize 2021


The fifth video demonstrates how to print sugar


Since Extruder V3 is a submission for the Hackaday Prize 2021, you will of course also find a page on Hackaday about the project with some additional information.

Extruder Details

Direct Granules Extruder V3 in operation
Figure 1:
Version 3 of my granulate extruder works (finally) reliably. Earlier versions had problems with clogging of the nozzle, which occurred particularly often after switching the printer on again and heating up.
The printer mechanism is a Zonestar QR2, from which I also took the heating element and the stepper motor for driving the auger (5mm wood screw).

Direct Granules Extruder V3, overview
Figure 2:
In order to meet the deadline for this year's application round, I created an interim report with the video. The same applies to the build instruction shown here:
It is a rough description of the extruder, more detailed information will follow in the coming weeks/months/years...

Direct Granules Extruder V3, detail photo
Figure 3:
The series of pictures gives a good overview of the construction. Everything is handmade.

Direct Granules Extruder V3, Example Zahnrad
Figure 4:
The central element is the auger screw:
This consists of a simple wood screw with a diameter of 5mm and a total length of 105mm. At the top I hard soldered a 25mm long piece of 1.5mm wire. I widened the neck of the brass nozzle with a 3mm drill so that the plastic can pass this point with less resistance - the tip of the screw would otherwise lead to clogging issues. An M8 nut is soldered to the screw head.

Direct Granules Extruder V3, Coldend
Figure 5:
The "cold side" of the extruder:
The central drilling is done first with an 8mm drill. Then the hole on the underside is widened to 9.5mm with a depth of 10mm. A small groove, about 3mm deep, is milled on the top, which improves the forwarding of the granulate.

Direct Granules Extruder V3, Hotend
Figure 6:
The "hot side" of the extruder is also made of 16x16mm aluminum:
First, a 5mm hole is drilled about 13mm from the edge. Then this hole is widened at the top to 9.5mm, about 8mm deep. The thread for the brass nozzle is made with a 6mm thread cutter.
Holes for the heating cartridge (diameter 6mm) and the temperature sensor (diameter 2mm) are drilled so that there is sufficient distance to the central hole.
About 3mm of material is filed on the upper side, so that only a small contact area with the coldend is formed.
Finally, two 3mm holes with a distance of 25mm are drilled on the lower edge. Two 90mm long threaded rods are screwed in there. Hotend and Coltend are screwed together using the two metal angles, made from 0.5mm sheet metal. The threaded rods allow you to adjust the components so that the central holes of the Coltend and Hotend are in line.
I filed about 3mm from the upper edge so that there is only a small contact area with the glass block. This reduces the heat flow to the coldend.

Direct Granules Extruder V3, thermal insulation from glass
Figure 7:
Thermal insulation:
In order to keep the heat flow from the hotend to the coldend small, there is a piece of 8mm glass as an insulator between the two components. I cut the 25x25mm block with the help of an electric tile cutter with water cooling for the diamond disc. I made the 9.5mm hole with a Dremel and a diamond-coated drill, also with water cooling.
A Teflon tube (about 10mm outer and 8mm innber diameter, 26mm long) runs from the coldend to the hotend and ensures the least possible friction on the walls.

"Pellets"

Getting granulate from old prints: Blender
Figure 8:
There is a lot to say about how to create granules (coming soon), here is just the short version:
Failed prints from PLA are shredded with a blender...

Getting granulate from old prints: sieving
Figure 9:
... then the shredded plastic is sieved. The grain size has a major influence on the functioning or non-functioning of the extruder! The can I used as a sieve has 2mm holes. Anything that doesn't pass the holes is put back into the mixer.

Download

The 3D files, made with OpenSCAD (including *.stl files) are available as Download-Package. That part of the extruder is identical to Version 2.

Sample prints

Direct Granules Extruder V3, sample print gear
Figure 10:
The print made in the first video is a gear. In good RepRap tradition, it is the pinion on the stepper motor of the extruder. A 1.0mm nozzle was used for printing in order to avoid clogging due to impurities in the granulate made from old parts.
Although the granulate consists of green and white grains, the plastic has been mixed relatively homogeneously to a light green color.
Material: PLA
Dimensions: 25x25x10mm
Nozzle: 1.0mm
Layer height: 0.2mm
Extrusion width: 0.7mm


Direct Granules Extruder V3, sample print gears with different speeds
Figure 11:
In the second video, I printed these gears at different speeds. The lack of an object cooling fan is particularly noticeable when printing at 60mm/s (far right) by the tips of the teeth bending upwards. There is also a flaw at the bottom of this gear, because I moved the printer on the table during the printing process in order to take different video shots.
Material: PLA
Dimensions: 25x25x10mm
Nozzle: 1.0mm
Layer height: 0.2mm
Extrusion width: 0.7mm


Direct Granules Extruder V3, sample print main gear
Figure 12:
In the third video, I printed the main gear of the extruder as a spare part. It took 4 hours to finish the job.
Material: PLA
Dimensions: 90x90x37mm
Print speed: 30mm/s
Nozzle: 1.0mm
Layer height: 0.2mm
Extrusion width: 0.7mm


Direct Granules Extruder V3, sample print chain link
Figure 13:
The chain link was also created in the third video. For the first time I used a 0.6mm nozzle. The object cooling fan is still missing. Stringing can be clearly seen, the closing of the nozzle obviously does not work yet.
Material: PLA
Dimensions: 27x25x12mm
Print speed: 20mm/s
Nozzle: 0.6mm
Layer height: 0.2mm
Extrusion width: 0.5mm


Direct Granules Extruder V3, sample print Rocket
Figure 14:
Example "Rocket":
Material: PLA
Dimensions: 100x100x150mm
Print speed: 30mm/s
Nozzle: 0.6mm
Layer height: 0.2mm
Extrusion width: 0.5mm
The rocket was printed during the Hackaday Prize video (openSCAD and STL files available as Download). On the tip you can see, that I should have screwed on the part cooling fan.

Direct Granules Extruder V3, Example Sugar gear
Figure 15:
Example "Pinion":
Material: Sugar (Sucrose)
Dimensions: 25x25x10mm
Print speed: 10mm/s
Düse: 0.6mm
Layer height: 0.2mm
Extrusion width: 0.5mm
A copy of the pinion on the stepper motor of the extruder has been printed here from sugar. Sugar is the generic term for a whole range of different, sweet-tasting substances - the household sugar used here consists of sucrose. The sugar comes out of the nozzle in a light brownish color. The reason is the caramelization reaction that takes place at temperatures above around 140°C - a pleasant smell spreads in my video studio that made me feel hungry.
The surface of the gear is not as smooth as it is when printing with ordinary plastics. The reason is the surface tension in combination with the significantly lower viscosity of the molten sugar:
The tip of the nozzle is always surrounded by a drop of liquid sugar. So it is surprising that the only 3mm small teeth of the gear are clearly visible. The gear is far from perfect, but at least recognizable as such for a first try. At the top, the tendency of the liquefied sugar to form droplets can be clearly seen. On the other hand, however, you can also see the layered structure of the print.

Direct Granules Extruder V3, Example Sugar Octagon
Figure 16:
Example "Octagon":
Material: Sugar (Sucrose)
Dimensions: 100mm Diameter on the base
Print speed: 10mm/s und 20mm/s
Düse: 0.6mm
Layer height: 0.2mm
Extrusion width: 0.5mm
In this experiment, I had initially printed the walls of the octagon at 10mm/s, which worked great. Later I increased the speed to 20mm/s, which soon afterwards led to a part of the wall breaking out. This happened when the printhead was on the opposite side. Obviously, due to the increased print speed and the cooling of the sugar, excessively high stresses built up in the walls and led to them breaking out. Household sugar is still damn brittle even in slightly caramelized form!

Direct Granules Extruder V3, Example Sugar, cracks
Figure 17:
Example "Octagon":
Material: Sugar (Sucrose)
Dimensions: 100mm Diameter on the base
Print speed: 30mm/s
Düse: 0.6mm
Layer height: 0.2mm
Extrusion width: 0.5mm
The brittleness can also be seen elsewhere:
If the print bed heating is switched off after a successful print, the object destroys itself.

Direct Granules Extruder V3, Example surface augar
Figure 18:
Example "Octagon":
Material: Sugar (Sucrose)
Dimensions: 100mm Durchmesser an der Basis
Print speed: 30mm/s
Düse: 0.6mm
Layer height: 0.2mm
Extrusion width: 0.5mm
If the printing is sufficiently fast, the sugar does not have time to form drops before it solidifies. With that, nicely smooth surfaces can be printed.

Direct Granules Extruder V3, Example Sugar Cone
Figure 19:
Example "Kegel":
Material: Sugar (Sucrose)
Dimensions: 100mm Diameter on the base
Print speed: 10mm/s
Düse: 0.6mm
Layer height: 0.2mm
Extrusion width: 0.5mm
As with all materials in 3D printing, you must keep the properties of sugar in mind in order to be able to achieve good results.

Direct Granules Extruder V3, Example Sugar Cone, print canceled
Figure 20:
Example "Kegel":
Material: Sugar (Sucrose)
Dimensions: 100mm Diameter on the base
Print speed: 10mm/s
Düse: 0.6mm
Layer height: 0.2mm
Extrusion width: 0.5mm
With increasing height, the diameter of the cone becomes smaller. This means that the sugar in one layer has not cooled down completely before the next layer is printed. As a result, drops form on the upper edge of the wall, which ultimately led to the printing being canceled.
Better results should be achieved with a heated chamber and a part cooling fan.




<<< Direct granules extruder V2         Longer LK5 Pro: Warping >>>


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