Importing DXF with bend line fails

[Joel Bäckström]

Hey! I'm trying to import a .dxf into a cadquery workplane using cq.importers.importDXF but get a "ValueError: Cannot build face(s): wires not planar" which I'm guessing is because there is a bend line on the sheet.

Should this be possible to import using the importDXF function? And if not, what options do I have to reading files like this? 

Adding a sample .dxf file as an attachment.

[Adam Urbanczyk]

DXF import is indeed limited to planar objects. If you need something 3D, try STEP.

[Joel Bäckström]

Yeah, we use STEP for some stuff as well. The problem here is that the files are provided to me in a given format, most cases DXF. 

How come other CAD-software supports it? 

[Adam Urbanczyk]

You are free to implement a plugin that does what you need and share it with the community. In the meantime your best bet is to convert your DXFs to STEP and import that.

[Jeremy Wright]

ezdxf is one of CadQuery's dependencies and can be used to pre-process DXF files. So you can remove the entities from the bend line layer so that the rest can be imported properly.

import cadquery as cq

from cadquery.vis import show

import ezdxf

def preprocess_dxf(input_dxf_path, layer_name):

"""

Removes bend and center lines from the DXF.

"""

# Read the original DXF file in

dxf = ezdxf.readfile("sheet-with-bend-line.dxf")

# Remove all entities from the layer, turning the layer off

# and/or deleting the layer definition is not enough

with dxf.entitydb.trashcan() as trash:

for entity in dxf.entitydb.values():

if not entity.dxf.hasattr("layer"):

continue

if layer_name == entity.dxf.layer:

# safe destruction while iterating

trash.add(entity.dxf.handle)

# Output the modified DXF as a copy

output_filename = input_dxf_path.replace(".dxf", "-copy.dxf")

dxf.saveas(output_filename)

return output_filename

# Work with the cleaned-up DXF

dxf_output_name = preprocess_dxf("sheet-with-bend-line.dxf", "DOWN_CENTERLINES")

bar = cq.importers.importDXF(dxf_output_name)

# The following line works to convert the wires into something that can be extruded.

# In the example, it ends up being a bar with pairs of holes down the x-axis.

# bar = bar.wires().toPending().extrude(10.0)

show(bar)

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