Week 05 — 3D Scanning and Printing

Overview

This week was about understanding what 3D printing makes possible and where its limits appear in practice. Instead of only reading generic rules, I tested two printers directly and observed how real prints behave under unsupported curved geometry.

I also explored the reverse workflow: converting a physical object into a digital 3D model. For this part, I used Polycam to capture and reconstruct a small object through mobile photogrammetry. This helped me understand the difference between a visually convincing scan and a fabrication-ready mesh.

This documentation covers both the group assignment, which focused on printer design-rule testing, and the individual assignment, which included an additive-only object and a 3D scanning workflow.

Group Assignment — Testing Printer Design Rules

For the group assignment, I compared two Bambu printers with different motion systems: the A1 Mini and the P1C. The objective was not simply to decide which machine is better, but to understand how printer structure influences the result when geometry becomes difficult.

Both tests were printed in PLA using the same benchmark model. The key area of observation was the large curved overhang, because it quickly reveals where a printer begins to lose control without support.

Printers Used

• Bambu Lab A1 Mini — bedslinger structure, open frame, easy setup
• Bambu Lab P1C — CoreXY structure, enclosed machine, more rigid motion

Test Setup

• Material: PLA
• Nozzle: 0.4 mm
• Layer height: 0.20 mm
• Supports: disabled
• Purpose: identify the practical overhang limit

Benchmark Model

A1 Mini Result (Red Print)

P1C Result (Yellow Print)

Close-up Observation

Critical Observation

The key result of this test is that both printers began to struggle at approximately 50° in the curved unsupported section. This is useful because it turns a generic design rule into an observed value under my own printing conditions.

In practice, this means that if I want a reliable print without support, designing for 45° or lower is a safer strategy.

Printing Summary

Under these standard PLA settings, both machines performed well. The difference was subtle rather than dramatic. The P1C felt slightly more stable, but the A1 Mini was also fully capable for this type of benchmark print.

Individual Assignment — Additive-Only Object

For the individual assignment, I designed a hollow LEGO-inspired block with enclosed internal geometry. The exterior is simple and familiar, while the interior demonstrates the core logic of additive manufacturing.

This object cannot be made subtractively because the internal curved geometry is fully enclosed. CNC tools cannot access the inside without destroying the outer shell. The structure can only be produced layer by layer using 3D printing.

Step 1 — Base Model

Step 2 — Hollow Structure

Step 3 — Slicing

Step 4 — Printed Result

What I Learned from the Object

This design made one important point very clear: additive manufacturing does not only allow complex geometry, it also introduces new constraints after printing. Once the internal volume is enclosed, post-processing becomes much harder.

• Hidden geometry is easy to model, but difficult to clean.
• Support planning matters more in enclosed volumes.
• Additive-only design is not about decoration — it is about fabrication access.

3D Scanning Workflows

For the scanning part of this week, I used Polycam on my phone to capture a real physical object and reconstruct it as a 3D model. I chose this workflow because it is lightweight and accessible: it only requires a phone camera, a stable object, and enough images from different angles.

The object I scanned was a small bird-shaped object. My goal was not to create a perfectly printable replacement part, but to understand the workflow from physical object to digital mesh, and to evaluate how reliable a mobile scanning tool can be.

Step 1 — Object Capture

Step 2 — Cloud Processing

Step 3 — Processed Scan

Step 4 — Detail Check

What I Learned from Polycam

Polycam is effective for quickly generating a 3D model from a real object. The overall shape and color information were captured well enough for visual documentation and concept reference.

However, the result also showed the limitations of mobile photogrammetry. The mesh was not geometrically reliable, and small features could be duplicated, softened, or distorted. Because of this, the output should not be treated as a precise fabrication file without further mesh repair, scale checking, and possible remodeling.

Reflection

This week made additive manufacturing much more concrete for me. It is one thing to understand overhangs or supports as abstract design rules, and another to see them appear directly in a print result.

The printer test was useful because it gave me a measured reference point: under my current conditions, unsupported curved geometry starts to fail at around 50°. That makes future design decisions much more grounded.

The hollow LEGO-inspired object helped me understand that additive-only design is not just about complexity for its own sake. The real issue is whether a tool can physically access the geometry. Once I started thinking in terms of access, the distinction between subtractive and additive fabrication became much clearer.

The Polycam scan also showed the limits of mobile photogrammetry. It captured the overall shape and color of the object, but small details were distorted or duplicated. This reminded me that a scanned model is not automatically a fabrication-ready model; it still needs checking, cleanup, and sometimes remodeling before printing.

Design Files

• Benchmark overhang test model (.STL)
• STL export of the final LEGO-inspired print (.STL)
• Polycam reconstructed model (.STL)