5. 3D Printing and Scanning¶

Objectives of the Week¶

Identify the advantages and limitations of 3D printing
Apply design methods and production processes to show your understanding of 3D printing.
Demonstrate how scanning technology can be used to digitize object(s)

Schedule¶

Wednesday, Jan 21st - Global Class - 3D Printing and Scanning

Thursday, Feb 19th: Scanning

Friday, Feb 20th: Printing

Assingments¶

Group assignment:¶

Test the design rules for your 3D printer(s)
Document your work on the group work page and reflect on your individual page what you learned about characteristics of your printer(s)

The link to the group work can be found here

Individual assignment:¶

Design, document and 3D print an object (small, few cm3, limited by printer time) that could not be easily made subtractively
3D scan an object (and optionally print it)

Principles of Additive Manufacturing¶

Manufacturing Approaches
Subtractive
- Excess waste material
- Generally more expensive
- Time consuming
- More precise
- Better for long-term use
- More available materials
Additive
- Very little material waste
- Cheap materials and operational costs
- Fast and user-friendly
- Complexity and design freedom
- Poor surface definition and tolerance
- Suited for prototyping

3D Printing¶

Class Notes

Properties
3-axis systems
Parameters
- Layer height
- Shells
- Infill
Input geometry
- 3D mesh (sliced)
Available Technologies
Extrusion (FDM)
- Cheap
- Material deposited layer by layer
Light Polymerized (SLA/DLP)
- Platform dips into resin
- Laser/screen polymerizes resin layer by layer
- More accurate
- Can use internal supports
Selective Laser Sintering (SLS)
- Laser sinters thin layers of powdered material
Printing Parameters
Shell
- Number
- Thickness
Infill
- Structure
- Density
Layer height
- Higher resolution = slower print speed
Overhang and support
- Use support if overhang is less than 45°
Part strength
- Weak between layers (vertical tension weakness)
- Print orientation is important
- Avoid sharp edges → use fillets/rounding
Materials
PLA
- Excellent visual quality
- Easy to print
- Biodegradable
- Not suitable for high temperatures
ABS
- Good mechanical properties
- Susceptible to warping
- High fume emission
Nylon
- High strength
- Wear and chemical resistant
- Low humidity resistance
PETG
- Food grade
TPU (Filaflex)
- Flexible
- Recommended for auxetics
HIPS
Workflow
Model in CAD software
- Must convert to mesh before export
- Must be a closed (watertight) shape
- Shapes cannot improperly share edges/surfaces
Export as STL
Software (Bambu Lab P1S)
Standard profile: 0.2 mm
Seam position
- Random → for round shapes
- Aligned → for sharp corners
Always scale and adjust before exporting
Orientation can be changed in slicer
Click “Slice Plate”
- Inspect layers with slider
- Check walls
- Ensure infill appears (if not, model may not be closed)
Machines
Ensure enough filament is loaded
Bend plate to remove print
Calibration tab must be at the back
Magnetic plate must align correctly
SD card located on back right of screen
Lab Rules
Book enough time for full print
Do not print overnight
Buying Spools
Local supplier: 3De Nou
SLA Printing
Platform pulls up from resin pool
Material solidifies layer by layer
Print time depends on vertical height
Timing
- First layer ~30 seconds
- Subsequent layers shorter (check layer count)
Software workflow
- Import model
- Select orientation
- Check for cavities
- Hollow model
- Add drainage holes
Advanced Materials
UV-curing resins (wax-like → casting)
Ceramic resins (kiln firing)
Electroplating
- Apply conductive spray
- Submerge in metallic solution
- Metal coating forms

3D Scanning¶

Class Notes

3D Scanning
Taking multiple images to reconstruct geometry
Matching corresponding points is the main challenge
Requires post-processing
Scanning Technologies
Structured Light Sensor
- Projects known pattern
- Fast and accurate
- High contrast improves detection
LiDAR
- Spinning laser
- Very fast
- Captures large areas
Touch/Digitizer
- Extremely precise
- Very slow
- Specialized equipment required
Scanning Process
Scan → Point Cloud → DEM → Terrain
Good scan practices
- Clean workspace
- Matte surface
- Consistent lighting
File formats
- STL → mesh (recommended)
- OBJ → includes color and texture
Equipment Available
Structured Light Scanner: Revopoint
Other Tools
Disappearing scan spray
Software
- Polycam
- AliceVision
Clay Printing
Software
- Repetier Host
- Rhino + Grasshopper
Parameters
- Pressure
- Nozzle size (affects layer thickness)
- Speed
Maintenance Checklist
Clean cartridge, extruder, nozzle, screw
Check bed leveling and Z calibration
Check belt tension
Check coupler (tight, not touching motor screw)
Check for air leakage (use Teflon if needed)
Common Problems
(Insert table from slides here)

Scanning Examples¶

As a class we tested hand held scanners and a phone mounted scanner. The link to the group work can be found here