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)

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)