#90 Negative Offset by EngraveStrategy

[sven lan]

PyCam dont Work with Negative Offset :-(

Engraving -0,50
Bounds all 0
Tool Cylindrical (d=1.0)

An unexpected exception occoured: please send the text below to the developers of PyCAM. Thanks a lot!
Traceback (most recent call last):
File "/usr/lib/pymodules/python2.7/pycam/Gui/Project.py", line 4041, in generate_toolpath
self.model, toolpath_settings, callback=draw_callback)
File "/usr/lib/pymodules/python2.7/pycam/Toolpath/Generator.py", line 62, in generate_toolpath_from_settings
backend, callback)
File "/usr/lib/pymodules/python2.7/pycam/Toolpath/Generator.py", line 226, in generate_toolpath
callback=callback)
File "/usr/lib/pymodules/python2.7/pycam/Geometry/Model.py", line 683, in get_offset_model
new_groups = group.get_offset_polygons(offset, callback=callback)
File "/usr/lib/pymodules/python2.7/pycam/Geometry/Polygon.py", line 982, in get_offset_polygons
group.append(line)
File "/usr/lib/pymodules/python2.7/pycam/Geometry/Polygon.py", line 238, in append
+ "polygon")
ValueError: A line with zero length may not be part of a polygon

[Lars]

The offsetting algorithm is quite fragile. It is not easy to guess, why it failed in the case above.
Maybe you could try to vary some parameters slightly (e.g. offset). Maybe it could be helpful to reverse the model direction and use a positive engraving offset?