Computational Fabrication 3D model Slicer

Group 3 - Lieven Libberecht, William Thenaers

Minimal requirements

• Program with input STL/OBJ file and output gcode file
• Basic GUI to go through slices step by step
• (+ render all paths in colors)
• Basic GUI for configuring essential parameters e.g. layer height, nozzle diameter, number of shells,…
• Support for Shells + infill (basic e.g. rectangular)
• (+ roofs/floors)
• Models can have holes!
• Support generation (basic rectangle structure)
• Optimize for print quality (not speed)

Possible extras

• Other types of infill (+ size)
• Adaptive slicing (thinner slices for some parts)
• Support for bridges (not requiring support) => nozzle cannot start in a void
• ~? Optimizing paths for speed
• Support structures to avoid toppling of objects (e.g. cube standing on 1 corner)
• Automatic orientation of model (XY rotation; optimization)
• Manual orientation of model (XYZ rotation and scale)
• Automatic centring of model (XY position)
• Indication of bounding box size and warning if it's larger than the Ender3 build plate (text turns red)
• Optimized support structures (zigzag + others + size)
• Adhesion with brim/skirt (+ size)
• Print time estimation (take speed per accumulated extrusion and sum them)
• Adjust slicing settings at runtime
  • Nozzle thickness (layer height)
  • Nozzle diameter (line thickness)
  • Filament diameter (optimized value for extrusion)
  • Number of shells (surfaces and borders)
• Preview of 3D object and drawing of colour coded polygons (with adjustable thickness and direction arrows)
  •       Contour polygons
  •       Contour shell polygons
  •       Hole polygons
  •       Hole shell polygons
  •       Surface fill lines
  •       Infill lines
  •       Adhesion and support lines
  •       Polygons that appeared "open" but were "fixed" to include them anyway
• Progress indication during slicing (also indicated by same colours for every phase)
• Slicing is multithreaded where possible
• Arc detection for polygons to see if it's a circle, so we could print an arc in GCode instead, but the firmware does not have this enabled, so it is commented out.

Progress

• Algorithm + UI for basic slicing of 3D model (3D view for STL visualizer + 2D view for showing slices)
• Erode perimeter with half the nozzle thickness (otherwise print will be too large)
• [Deadline 14/11] Generate g-code for a perimeter of a single slice
• And try 3D printing
• Extend data structure to support holes in object/polygon
• Generate second shell
• Generate basic rectangular infill structure (line per line intersection between grid and polygon slices)
• [Deadline 7/12] Extend g-code generation and 3D print simple object that does not require support structure
• Calculate regions + generate paths (+ g-code) for floors and roofs
• Try 3D printing a closed object (roofs + floors) that does not require support
• Features + algorithms for support structure generation
• [Deadline 6/01] Implement all other minimal requirements (e.g. basic UI controls for settings)

Problems

• On rare occasions, some points or triangles disappear, resulting in layers or partial layers to be empty, probably in the algorithm to connect polygons
  • They go away resulting in other polies to be wrongly marked as contour or hole
• Zigzag support sometimes disappears on some layers
• Stringing issues, despite doing the same things as Cura. Some strings cause the connections to be solid.
• Overlapping shells are not joined together, but are removed.
• Sometimes "phantom surfaces" are found and filled in, although visually there shouldn't be one

TODO

• Scale slider naar 1 dim ==> 1.0 == 1 mm
• Sliders met textfield voor manual input (of sliders weg en enkel [real scale; percentage])
• Clipper (polygon intersection etc)?
• 2de viewport voor 1 slice te previewen => met slider voor slice te selecteren
• Slice preview met kleuraanduiding in object of bovenkant object wegnemen om slice te zien
• Nozzle thickness parameter
• Indicatie van grootte
• XY translate en rotate op object voor te slicen (=> transform individual polygons...)
• Slice opstellen door uinion van vlak met dikte NozzleThickness en object (met Clipper?)
• Slice opstellen door triangle en plane intersection ipv 3D intersection
• Add ambient light ~~
• Basic SliceModel class with slice plane and sliced model preview
• Add brim/skirt (erode to outer on slice 0)
• Make offsets for every contour/hole and then union them
• Surface (floor/roof) herkenning
  • ✔ Refactor code to split generation
  • ✔ Subtract Layer+1 from Layer+0 for roofs
  • ✔ Subtract Layer+0 from Layer+1 for floors
  • ✔ Add to separate list
• Surface invullen met patroon => denser infill, mss met offsets ipv rects or zigzag?
  • ✔ Shells en dense infill beter 1.5*nozzle thinkness => Cura
  • ✔ Dense infill korte segmentjes verwijderen na clipping
    • ✔ OF Line clipping in de plaats => Paths met lines clippen met inner shell
• Overhang herkenning voor support (diff van subtraction > nozzle width => support needed)
• Support toevoegen voor overgang
• Check Cura output to identify stringing issue? Nothing found...
  • ==> The solution is probably to retract and reset extrusion if the travel distance to the next polygon is too big (>5 mm or something)
• Report schrijven