7. Cnc25D API Outline Utilization¶

7.1. Transformations at the figure-level¶

The description of a 2.5D part can require several outlines. Typically one outline is the outer shape of the part, the other outlines are holes in this part. In the Cnc25D API, a list of outlines is called a figure. After creating such a list, you can directly display this figure, write it in a file or extrude it in 3D with FreeCAD.

7.2. Display a figure in a GUI¶

cnc25d_api.figure_simple_display(graphic_figure, overlay_figure)
return 0

graphic_figure is a list of format-B outlines to be displayed in red. overlay_figure is optional and could be used to display an other figure in orange when the overlay is active. A common practice it to set graphic_figure with the outlines returned by cnc_cut_outline() and to set overlay_figure with outlines returned by ideal_outline(). So you can see your created format-A outlines and the final format-B outlines. Notice that you can also directly use format-A or format-C without converting them in format-B with ideal_outline(), but you will get a warning message.

If you want more control on the figure display like new colors, width or animations, then you should use outline_arc_line() and Two_Canvas directly.

7.3. Write a figure in a SVF file¶

cnc25d_api.write_figure_in_svg(figure, filename)
return 0

7.4. Write a figure in a DXF file¶

cnc25d_api.write_figure_in_dxf(figure, filename)
return 0

7.5. Extrude a figure using FreeCAD¶

cnc25d_api.figure_to_freecad_25d_part(figure, extrusion_height)
return FreeCAD Part Object

To create a 3D part from a figure, the function figure_to_freecad_25d_part() makes the assumption that the first outline is the outer line and the remaining outlines are holes.

7.6. Detailed transformations at the outline-level¶

After getting a Cnc25D format B outline from the cnc_cut_outline() function, you probably want to use this outline in CAD tools. The function cnc25d_api.outline_arc_line() lets you transform the Cnc25D format-B outline into one of this four formats: freecad, svgwrite, dxfwrite, tkinter.

cnc25d_api.outline_arc_line(outline-B, backend) => Tkinter or svgwrite or dxfwrite or FreeCAD stuff
  with backend=['freecad', 'svgwrite', 'dxfwrite', 'tkinter']

7.6.1. freecad¶

outline_arc_line(outline_B, ‘freecad’) returns FreeCAD Part.Shape object that can be used easily in the classic FreeCAD workflow:

my_part_shape = cnc25d_api.outline_arc_line(my_outline_B, 'freecad')
my_part_face = Part.Face(Part.Wire(my_part_shape.Edges))
my_part_solid = my_part_face.extrude(Base.Vector(0,0,20))

Notice that FreeCAD conserve the arc geometrical entity during its complete workflow. So after extruding the outline, slicing the part and then projecting it again in a DXF file, you still get the arcs you have designed in your original outline.

7.6.2. svgwrite¶

A Cnc25D format B outline is a 2D vectorial shape that can be transposed in a SVG file. SVG file is one of the usual input format for the 3-axis CNC tool chain. This snippet let you dump the Cnc25D format B outline in a SVG file:

import svgwrite
my_outline_B = [ .. ]
object_svg = svgwrite.Drawing(filename = "my_ouline.svg")
svg_outline = cnc25d_api.outline_arc_line(my_outline_B, 'svgwrite')
for one_line_or_arc in svg_outline:
  object_svg.add(one_line_or_arc)
object_svg.save()

Cnc25D relies on the Python package svgwrite from mozman. Use Inkscape to review the generated SVG file.

Warning: The SVG format supports the arc graphical object but the Python package svgwrite has not implemented yet the arc constructor. So Cnc25D transform each arc of the outline into a series of small segments. This might be an issue for certain CNC tool chain or for some designs.

7.6.3. dxfwrite¶

A Cnc25D format B outline is a 2D vectorial shape that can be transposed in a DXF file:

import dxfwrite
my_outline_B = [ .. ]
object_dxf = DXFEngine.drawing("my_outline.dxf")
#object_dxf.add_layer("my_dxf_layer")
dxf_outline = cnc25d_api.outline_arc_line(my_outline_B, 'dxfwrite')
for one_line_or_arc in dxf_outline:
  object_dxf.add(one_line_or_arc)
object_dxf.save()

Cnc25D relies on the Python package dxfwrite from mozman. Use LibreCAD to review the generated DXF file.

Warning: Like previously, the DXF format supports the arc graphical object but the Python package dxfwrite has not implemented yet the arc constructor. So Cnc25D transform each arc of the outline into a series of small segments. This might be an issue for certain CNC tool chain or for some designs.

7.6.4. tkinter¶

During the early phase of the design, you just need to view the outline (that still might be under-construction) without using the powerful FreeCAD or dumping files. This is the purpose of the Tkinter GUI. Check the design example cnc25d_api_example.py generated by the binary cnc25d_example_generator.py or check the file cnc25d/tests/cnc25d_api_macro.py to see how to implement this small graphic user interface.

cnc25d_api.Two_Canvas(Tkinter.Tk()) # object constructor