Assignment 5

In this week’s assignment, I explored 3D printing and scanning processes to print a custom-designed lamp inspired by a Pinterest Model. In order to make sure that my design can't be manufactured subtractively, I decided to add underneath the figurine a cavity, where I inserted a sphere and enclosed it from the sides to add complexity to the design. In my opinion, it gives the illusion that this figurine is standing on a spherical pedestal that is surrounded by prison-like grid, improving the visual appearance of the lamp and it is up to the viewer whether to interpret it as empowering and freeing or restricting and limiting!

I learned new skills like adding Sphere, manipulating using the move and rotate functions to make sure it is inside the box.

To make the design a little bit more complicated, I decided to add grid-like structure that encloses the sphere box, with leaving some gaps in between for visibility. This enables me to put the claimed advantages of 3D printing into test, namely making more complicated shapes and cavities in the design.

Other functions I already used like extrude for cutting and joining walls and stairs together, also adding arcs into my designing by extruding half squares together with rectangles on each side to form this Arch door entrance. It was quite fun.

I also added a little figurine by using the spline tool and drew it on the plane, then rotated it 90° to appear like it is standing on the platform.

To form the arch ceiling, behind it, I added an Offset Plane right behind the figurine to sketch another arch on it and created the 3D illusion.

For visual effects, I added Fillet to the arch and Chamfer onto the stairs to smoothen them out. The overall piece was 150 mm long, 100 mm wide, and 60 mm high.

Note: For basic functions I attempted, you can check Week 2 - Computer-Aided Design.

After exporting my design as .STL file, I installed Ultimaker Cura 5.8.1 and I opened my saved file. To set the setting, I selected material to Generic PLA 0.4 AA, the infill density to 15%. and infill type to triangle. In order to make sure my object does not have any overhang or sagging, I ticked the option for "support". For the support structure, I selected Normal and the placement to everywhere and the support z distance to 0.4mm. These settings were expected to require a lot of post processing, but I did not want to change my design so I had to take responsibility for my decision.

After slicing, it stated that the print will need 11 h 5 min.

With the normal type support, the material could not be removed at all without breaking pieces apart. Due to the print settings, namely the support gap (distance between the object and the support material) and the density of the support material added, it was almost impossible to remove the support material without damaging the object itself. Since it was my first complicated design experience, I wanted to test printing with support material with the ultimaker. Although my local instructor Ahmed mentioned to me that with the ultimaker, removing the normal support material is very tricky and difficult, I wanted to test it myself and learn from my own mistakes. Moreover, due to the lengthy print time of the full sized design with the support material, I had to deal with the time pressure and improvise a simple alternative to fulfill the requirements of my assignment. Therefore, I decided to scale down my design and try with a different 3D printer and a different support type.

I decided to give it a shot with the organic support type using the Bambulab that Lysander characterized. Furthermore, I reduced the scale down to 35%, so it is significantly less time and material costly. After slicing, it took roughly 45 min to print!

Since printing my lamp was not a very successful practice using the ultimaker normal support setting, I designed the box with the sphere inside and I added a pipe going through the center of the sphere by sketching a circle at the bottom surface of the cube and extruding it from top to bottom of the cube, and set the operation to join, so the support is technically not needed.

Looking at the cross-section analysis, the geometry of the sphere inside the housing makes it hard for any CNC machine that is not multi-axis to manufacture! The machine needs to access the area inside the housing and remove the extra material between the ball and the inner wall of the curve. Unlike additive manufacturing, which allows forming cavities or partially enclosed geometries without complicated toolpaths. See Week 7 - Computer-controlled Machining (Subtractive Manufacturing) for further input on CNC Machining.

The print turned out very well! You can see because of the borderline bridging with the pipe going through the ball and the short distance (~2.7 mm) between the ball and the inner roof of the cube, no support material was needed! Moreover, the overhang of the ball (angle <= 30°) relative to the horizontal line helped prevent a spaghetti-like structure from hanging underneath.

Subtractive manufacturing principle is based on removing material from a solid block, which limits it to objects that the cutting tools can easily reach. In my lamp design, there are many intricate details—like the curved arches, and internal cavity with the sphere inside—which makes it challenging for CNC machine to make it accurately. In the case of 3D printing (additive manufacturing), the piece is built layer by layer, which allows creating delicate figures, without the constraints of tool access or the large amounts of material waste like in subtractive methods.

For this task, I decided to 3D scan my teammate Mika's Week 5 and vice versa, so we helped each other! For calibrating and setting scanning parameters, I used Shining 3D. After we calibrated EinScan H2, which is a scanner primarily used to scan human bodies, I started setting the parameters for the scanning progress. I selected the scan mode to be "IR Mode". Then, I created a new project folder and named it "MikaScan". Scan Target was set to "Portrait", the alignment to be "hybrid", resolution to be "medium".

Afterwards, I started slowly with the machine scanning all angles trying to get as clean of a scan as possible. Finally, I pressed done and manipulated the scan in the software. I removed random points. After being satisfied with the result, I carried on with "optimizing and generating point clouds". This is done by the software to try and patch missing points from the scan.

Then, for meshing I set the mesh quality, filter, and smooth to "medium".

Lastly, I saved the files in all types (.stl, .obj, .ply, .mdf), and I scaled down the size to 30%. These files could be used for further processing in case Mika wants to 3D print a miniature version of himself :D.

After Mika scanned me and the mesh turned out to be very good, I was curious to 3D print the result! For processing, I used PrusaSlicer and MeshMixer. For the print to be stable, I designed a small square base using Fusion360 and exported it as .stl file. Then, on Prusa, I opened my scan and tried to manipulate it, making sure that the bottom surface of the feet is flat and leveled. For this, I rotated the perspective 180°, used the function "place on face", selected the bottom surface, then performed function "cut". The print was scaled down to 20%, ending up with the dimensions of 67 × 21 × 17 mm.

Then, I saved the new version of the scan and reopened it in MeshMixer to combine the base and the figurine into one .stl file. First, I dragged and dropped both files. Then I went to Edit > Transform in order to select the right coordinates for the figurine to be placed right on top of the base.

After placement was checked from every angle, both the base and the figurine were combined using the combine function. Finally, to set the printing setting, I went back to PrusaSlicer. First, I switched from "Beginner" mode to "Expert" mode to be able to manipulate more settings. Since I learned from my struggle with the normal support, I knew more confidentyl how to approach the printing settings for my miniture! Therefore, I went to "print setting" and ticked on generate support material, set the style to organic, and ticked on Support on build plate only.

Finally, the print was ready for slicing. Printing time was 2 h 2 min.

While trying to upload the original mesh with 100% resolution, I hit the soft limit for the GitLab repo storage (941 MB). I reset my repository by cloning the old version from my repo locally, then adding slowly from the fresher local version folder, pushing and committing step by step. Now, only the STL file for the figurine was left. Therefore, I had to use QuickSurface to reduce the mesh down to 5% (8.5 MB). The only downside is that it’s not open-source, but we have it in the lab PCs so why not use it to serve the purpose!

For comparison between the old and new mesh, I opened both STLs in Slic3r. If we zoom in, we see the triangles being more rough in the reduced version. However, for 3D printing, the difference will not be visible.

All I can say is that it took a long time and maneuvering with pliers to remove all the support material. I will try next time to have a design that requires less support!

Advantages: 3D printing offers design flexibility, which enables printing of intricate geometries and complex structures that traditional subtractive methods cannot easily achieve. Additionally, it minimizes material waste by forming objects layer by layer and supports rapid prototyping.
Limitations: On the downside, 3D printing is often a slow process compared to other techniques such as laser cutting, and the printed objects often require post-processing. Additionally, the selection of filament depends on the mechanical properties of the printed objects that serve the function you desire!

Reference: Xometry. (n.d.). Subtractive vs. additive manufacturing. From Link