Dude about slicing process...

  • Hi,

    I have a dude about slicing process, I expose:

    • With cad software you draw a dome, for example... This dome its a solid watertight, drawed by 3d cad with real curves...
    • For slice this dome, you export as STL.... And he comes the "issue", a STL, its formed for triangles... The smooth 3d dome, its transformed in triangle facets... More or less, depend of tolerance choosed in the export process. No?
    • These Stl, triangulated mesh, its imported in slicer... And these software (cura, slic3r, patio,...) create the gcode... But never slicer software create real curved slices, no? The Stl file are composed with triangulated faces.. The fact, in printed curved surfaces, can be observed these facets, smooth.

    The gcode is composed of straight lines, small lines ... No?

    Think I have see a gcode for arcs. When it's used?


  • administrators

    Correct, STL files can only represent facets with straight edges, which is the main reason why slicers generate straight line segments to approximate curves.

    The G2 and G3 codes are generated by some programs that generate GCodes for CNC machines, and perhaps for laser cutters

  • Think I have see a gcode for arcs. When it's used?

    G-Code for arcs are mostly a historical artifact from the days when G-Code programs might be handwritten and controllers only had a few kB of memory.

    Modern CAMs will have an option to use circular movements where possible, but the truth is that modern toolpaths just cannot be expressed with arcs. Even if you are cutting prismatic shapes a constant engagement toolpath will be a mix of helixes, spirals, and trochoids, not arcs:

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    On a modern controller there really isn't any advantage to arcs - memory is plentiful and you have 300+ segment lookahead. When your g-code is going to be 99.99% line segments anyways, why bother using arcs at all?

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