Week 5 : 3d printing and scanning

group assignment

here is the link to the group assignment page group assignment week 5

During the class, we collaborated to prepare a file to print on the resin printer.

we learned how to position it, to add holes for the fluid to escape.

and then we saw the post processing steps of cleaning with acetone and putting the model under a UV light for curing.

notes

Week 5 – 3D Printing, 3D Scanning & Paste Printing

Class notes from the global lecture and local sessions.

Global Class Notes

The global class introduced the basic ideas behind 3D scanning and 3D printing. We discussed how scanned objects are digitally reconstructed and reviewed major additive manufacturing processes such as FDM, FFF, and SLA. We also revisited important concepts such as additive versus subtractive manufacturing, STL files, mesh geometry, slicing software, overhangs, supports, and print orientation.

the class notes were uploaded by me into chatGPT to create definitions and summaries of the concepts learned.

Introduction to 3D Scanning

3D scanning captures the shape of a real object and converts it into a digital model. The object is first recorded as many points in XYZ coordinates. These points form a point cloud, which is then converted into polygons and finally into a mesh. This mesh becomes the digital representation of the scanned object.

3d scanning my coffee cup and me

Binocular Vision and Triangulation

One scanning method uses binocular vision, which works similarly to human eyesight. Two points of view observe the same object, and triangulation is used to calculate the position of the object in space. This allows the scanner to identify depth and build up the geometry of the object.

3D Printing Overview

We learned that 3D printing has existed in some form for almost one hundred years. It belongs to additive manufacturing, where material is added layer by layer to build an object. This differs from subtractive manufacturing, where material is cut away from a larger block.

Types of 3D Printing

• FDM / FFF – Fused Deposition Modeling or Fused Filament Fabrication. This is the common filament-based process where melted plastic is deposited layer by layer.
• SLA – Stereolithography. This is a resin-based printing method where liquid resin is cured with light.

STL, Meshes, and Slicing

We reviewed how 3D models are prepared for printing. Models may begin as NURBS surfaces or as mesh geometry. If the model is made in NURBS, it is converted into a mesh and then exported as an STL file. The STL is then processed in slicing software, which generates the machine instructions needed for printing.

Overhangs, Supports, and Orientation

Overhangs are areas of a model that extend outward and may need support during printing. Supports are temporary structures added by the slicer to hold these parts in place. Orientation is also very important because it affects support usage, surface quality, print time, and part strength.

Local Class – FDM Printing with Shyam

The first local class focused on FDM printing and the parameters that affect print quality, print strength, and printing efficiency.

Infill

Infill controls the internal structure of the print. It changes the amount of material inside the object and affects both strength and print time. We learned that zigzag infill is usually used only for objects that are intended to bend.

Layer Height

Layer height affects both print quality and duration. Lower layer height gives higher quality and finer detail, but it also increases print time. Higher layer height makes the print faster but reduces surface detail.

Supports

Supports help hold up parts of the model that would otherwise collapse during printing. Their need depends on the geometry and the orientation of the object.

Part Strength

FDM prints are stronger along the layers and weaker across them. In other words, parts are generally stronger parallel to the print layers and weaker perpendicularly because the layer bonding is more fragile than the material inside a single layer.

Ribs and Fillets

We learned that ribs and fillets can strengthen a model. Ribs increase stiffness, and fillets help reduce stress concentration around edges and corners, which can improve the structural performance of the printed part.

Materials

• PLA – easy to print and commonly used for prototypes.
• ABS – stronger and more heat resistant, but more difficult to print.
• PETG – durable and useful when more strength or flexibility is needed.
• TPU – very flexible and suitable for soft parts.
• HIPS – useful as a support material and can be dissolved in the appropriate solvent.

Generative Design and Modeling Workflow

Fusion was mentioned as a software used for generative design, although for this class I used Grasshopper instead. The general workflow is that the model is created either as NURBS or as mesh geometry, and if it starts as NURBS it must be converted into a mesh before export as STL.

Non-Manifold Geometry

We learned that non-manifold edges can create errors in 3D models. This often happens when objects overlap without being properly joined with a Boolean union. Problems like overlapping faces or broken geometry can cause slicing issues and failed prints.

Local Class – SLA Printing with Dani

The afternoon local class focused on SLA resin printing, its workflow, advantages, and preparation requirements.

Benefits of SLA Printing

SLA printing can produce highly detailed parts with smooth surfaces. One important advantage is that print time is mostly related to the height of the print and number of layers rather than the number of objects placed on the build plate. This means several objects of similar height can often be printed in the same amount of time as a single object.

Printer and Software

We learned about the Saturn 4 resin printer and the use of ChituBox to prepare SLA files. ChituBox is used to orient models, generate supports, and set slicing parameters before printing.

SLA Design Considerations

• If a model has closed cavities, holes need to be added so that liquid resin can escape.
• The orientation should usually be oblique, diagonal, or sideways to reduce suction and vacuum effects.
• Bottom exposure time must be adjusted depending on the material being used.

Cleaning and Preparation

We learned that isopropyl alcohol must be used to clean the machine and printed parts. It is important to clean the build plate, the tray bottom, and other relevant surfaces before starting a print and during post-processing.

Post-Processing and Electroplating

Another interesting point from the session was that resin prints can be electroplated after printing, which opens up possibilities for different finishes and material effects.

Multicolor Printing and Material Waste

We also discussed that multi-color printing creates a lot of material waste because the printer has to purge filament during color changes. To reduce waste, it may be better to orient the model differently or print it in separate parts.

Local Class – 3D Scanning with Adai

The local 3D scanning session introduced LiDAR scanning, point clouds, and photogrammetry workflows.

LiDAR and Point Clouds

LiDAR scanning records a large number of points around an object, often forming a dome-like field of information. These points make up a point cloud, which is later processed into a mesh by joining edges and forming surfaces.

Photogrammetry

Photogrammetry is the process of creating a 3D model from many photographs. By comparing overlapping images of the same object, the software reconstructs shape and depth and generates a point cloud and mesh.

AliceVision

AliceVision was mentioned as an open-source 3D scanning and photogrammetry software that was considered very good, especially at one point in time.

Good Practices for 3D Scanning

• Take many photos from many angles.
• Keep the lighting as consistent as possible throughout the scan.
• Transparent objects are difficult to scan.
• To scan transparent objects, it may help to spray them with dust or with a disappearing scanning spray.

for the demonstration, we 3d scanned my coffee cup.

and then we scanned me!

we then saw how to process the scans and create 3D models from them.

Paste Printing

We also had a session on paste printing, which I found very exciting. I am interested in eventually converting my old Ender DIY printer into a paste printer using an air compressor system, although for now I am mainly observing and learning from the process.

Yield Strength and Pressure

One important thing to consider in paste printing is yield strength, which is the pressure needed to push the material forward. The right pressure depends heavily on the material mixture, so testing by feel and repeated experimentation is necessary to find the correct settings.

Clay Extruder Kit

We learned that there is a clay extruder kit where many of the parts can be fabricated, while some parts can be purchased separately. Teflon tape can be used around threaded pipe connections to help prevent air leaks.

G-code in Paste Printing

We reviewed the basic structure of G-code, which generally includes a header, a toolpath, and a footer. In paste printing, the G-code can be controlled more directly so that movements can be slowed down and adjusted carefully depending on the behavior of the material.

Key Takeaways

• 3D scanning turns real objects into point clouds, polygons, and meshes.
• Triangulation and binocular vision are important principles in scanning.
• FDM and SLA are two major 3D printing methods with different workflows and material systems.
• Layer height, infill, supports, and orientation strongly affect print quality and strength.
• FDM parts are stronger parallel to the layers and weaker across them.
• Photogrammetry depends on good lighting, many photos, and careful image capture.
• Paste printing requires control over pressure, material consistency, and machine movement.