Week05 | 3D Scanning and Printing

Overview

Group assignment Tested and characterized the design rules and performance limits of the lab's 3D printers (FDM and resin). Reflected individually on key printer characteristics, tolerances, limitations, and implications for design.
Individual assignment
Designed and 3D printed an object that cannot be easily fabricated subtractively (e.g., complex internal geometries, interlocking parts, or organic forms).
Performed 3D scanning of an object (with optional reprinting of the scanned model).

Group assignment

Documented here on group assignment page. In collaboration with the our group, we evaluated the design rules and practical capabilities of the 3D printers available at Super Fab Lab Oulu. The objective was to generate reliable data on geometric and material constraints to inform future design decisions.

Key tests included:

Overhang angles and support requirements
Bridging performance (maximum unsupported span)
Clearance/tolerance for assemblies (press-fit, sliding, snap-fit)
Dimensional accuracy and shrinkage/expansion
Minimum feature size, wall thickness, and fine details
Surface finish quality and layer anisotropy (strength variation by build orientation)
Infill patterns and mechanical behavior

From the group tests, I learned that our FDM printers (Ender 3 Pro and CORE One) perform reliably for overhangs up to ~45° without supports but show deformation on longer bridges (>8 mm) and horizontal extensions (>2 mm unsupported). Dimensional accuracy has slight expansion on outer features (~0.2–0.24 mm) and anisotropy affects mechanical strength along vs. across layers. The Heygears resin printer excels in fine details and surface quality but requires post-processing. These constraints guide my design choices (e.g., adding supports for complex overhangs and orienting parts for optimal strength).

Individual assignment

Before you start using a 3D printer, I strongly recommend reading this glossary to become more familiar with the key terms here. There are some important measurement rules that anyone who wants to print a part has to know to print accurately. Briefly, these include: overhang, clearance, angle, bridging, wall thickness, dimensions, anisotropy, orientation, surface finish, and infill. We were able to test many of them in our group assignment.

3D Design

For this part, I watched several videos on YouTube and here. However, I decided to create the design entirely by myself. I am planing a design a part that can not be made subtractively, It is a kind of toys for kids to play.

I used Fusion 360 for 3D design, I started sketching by selecting the top view and creating a sphere at the origin point (0, 0, 0) with an 8 mm diameter. why 8 mm? I just wanted to design a small toys. Not logical reason behind it, It could be any dimension. This is the small ball (sphere) in the middle that everything will lock inside it.

Next, I created a sketch and drew a circle (shortcut R) with a 7 mm diameter (later adjusted to 7.5 mm). I then extruded it (shortcut E or Q) on both sides and set the operation to Cut. Here I cut a straight hole through the middle ball so a tube can pass through it later.

I continued sketching by creating a circle in the right-side view with a 20 mm radius, I am planning to use this circle to create Torus. I also created a small circle (radius of 2 mm) at the center, which I later used as the axis for the circular pattern. I drew a big circle (20 mm radius) that is the path the tube/ring will follow.

Then, I created another circle in the top view at the origin point with a 5 mm diameter. After that, I selected the Torus tool.

I made one single ring (like a donut) that goes around the big circle. Next, I used the Circular Pattern feature. Finally, I exported the design in STL format for slicing and printing.

Now I told Fusion 360: copy this ring 7 more times and put them evenly around the center → that makes the full chain of 8 locked rings. And here is the final design:

This is the finished toy, all 8 rings are locked together and around the center big tube / ring, and you can’t take them apart without breaking something.

3D Printing Process

Before proceeding to the detailed slicing steps, note that in Week02, I used IdeaMaker to prepare models for the Raise3D Pro2 Plus printer.

For this week assignment, I want to print it with Prusa CORE One L printer, so I do slicing using PrusaSlicer. I import the stl file:

Rotate the model:

Go to printer setting and from Support material tab chose the support style to be Organic:

Backed to plater, in the right panel, select the printer and do the needs setting: (Prusa CORE One L), filament (Generic PLA), support Everywhere, 15% Infill, and height layer is 0.15:

Slice the model, check the G-code and upload it to printer.

Insert the filament in printer and check the plate, make sure it is empty and clean:

Print Results and Post-Processing

The print completed successfully on the Prusa CORE One L with generic PLA. There were no layer shifts, warping, or bed adhesion failures, and the model released cleanly from the build plate. At 0.15 mm layer height and 15% gyroid infill, the surface showed typical FDM layer lines but good overall detail on the toys. The interlocking rings maintained their freedom of movement with no fused sections.

Post-processing was minimal but necessary due to the enclosed geometry. Most of too small organic supports came off easily by circulating small rings; however, some tighter internal supports near the tube-sphere junctions required careful to avoid damaging the thin walls. The final toy feels sturdy, the rings articulate smoothly, and the captive design works as intended—proving additive manufacturing's advantage for this topology.

Why the design cannot be made subtractively

The design is a closed chain of interpenetrating tube-and-sphere links that mutually enclose/lock one another in a topologically complex, non-planar manner. This creates internal voids, undercuts, and inaccessible surfaces in multiple directions at once. Such geometry cannot realistically be produced subtractively with conventional CNC milling, turning, or laser cutting, as there is no feasible tool access path to machine the enclosed/internal features without either impossible multi-axis contortions, destructive disassembly, or assembling the piece from separate components afterward.

3D scanning

There are two available 3D Scanners at Oulu super FabLab. The object I scanned was my personal computer mouse.

Scanner setup and settings

Scanner: structured-light 3D scanner (tripod-mounted) with motorized turntable and calibration board.
Software: Creality Scan.
Scan mode / tracking: Normal mode, Small object size, Geometry tracking.
Capture stats / settings: ~1834 frames, ~14,987 points captured, working resolution ≈0.15 mm.
Mesh processing: noise removal 63%, remove isolated parts 0%, fill small holes 5 mm perimeter, smoothing = none; resulting mesh ≈1M triangles.

First, I opened CrealityScan4 and created a new project.

Creality Scan is a 3D scanning software designed for scanners under Creality 3D, with rich features to help users achieve high-quality scanning and complete model building. The software supports practical functions such as one-click model optimization, multi-position auto-alignment, automatic denoising, topology simplification, color texture mapping, etc. It can also export 3D models and point cloud data in STL, OBJ and PLY formats, which makes users' operation easier and more efficient.

Reference

Next, I previewed the object before starting the scan.

If the preview appears green, it indicates that the object is being detected correctly and is ready for scanning. I rotated the object three times during the process to capture all sides.

After completing the scan, I used the mesh processing tools to clean and refine the model.

The final model can be exported as an STL file. However, the exported STL file was 44 MB, so I did not include it in the Files I Created section.

Comment on result:

The scanning result was acceptable but not as accurate as expected. The object (mouse) has curved surfaces on the side, and the scanner was not able to fully capture the geometry under that curves. Because of this occlusion, some areas were not scanned and small empty regions appeared in the mesh under the curved part of the object. This shows a limitation of the scanner when capturing areas that are difficult to reach or not directly visible during the scanning process.

Reflection

This week deepened my understanding of additive manufacturing through hands-on testing, design, printing, and scanning. Key learnings include:

How to operate different 3D printers (FDM like Prusa CORE One L) and slicers (e.g., PrusaSlicer vs. IdeaMaker from Week 02), including the importance of printer-specific settings for quality and reliability.
Selecting appropriate parameters (layer height, infill, supports, orientation) based on design requirements and material behavior.
Properties of common materials (e.g., PLA's ease of use but anisotropy in strength) and how to choose them for mechanical or functional needs.
Core design-for-print principles: overhang limits, bridging distances, clearance/tolerances for assemblies, minimum wall thickness, dimensional accuracy (±0.1–0.2 mm typical in FDM), build orientation effects on strength/surface finish, and infill patterns for weight vs. strength trade-offs.
Differences between FDM (layered, anisotropic, affordable) and other technologies like resin (higher resolution, isotropic, better details but more post-processing).
Fundamental contrast between additive (building layer-by-layer, enabling complex internal features) and subtractive manufacturing (removing material, limited by tool access).
Practical techniques like the teardrop shape for printing near-horizontal holes without supports, reducing material waste and post-processing.

Overall, the group tests highlighted real-world printer limitations (e.g., bridging ~8–12 mm max unsupported, overhangs failing beyond ~45° without supports), which directly informed my design decisions—such as adding organic supports and optimizing orientation for the toroidal rings. The scanning process revealed challenges with reflective/shiny surfaces (like my mouse's plastic). This week reinforced that successful 3D printing combines good CAD practices, informed slicer choices, and awareness of machine constraints. Looking ahead, I'd experiment more with advanced infills or multi-material if available.