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Message #20268
Re: dxf: import 4 arcs
I 'rewrote' the DXF R12 conversion procedure for the manual as follows.
I checked it like this and this works with the original DXF file from
Marcos.
Does this reflect the general understanding?
==== Notes on importing DXF files
The *DXF* import capability in KiCad is limited as there is no support
for 'advanced' shapes like *POLYLINES* and *ELLIPSIS*. For best results,
*POLYLINES* need to be broken into their original simpler shapes and
*ELLIPSIS* and other advanced curve shapes need to be converted into a
series of short line segments to approximate the shape.
That an entity in a DXF drawing is a *POLYLINE* , can be noted in
LibreCAD when you try to select the shape and the whole shape
consisting of multiple curves and lines gets selected as one.
To break up such a *POLYLINES*, use LibreCAD as follows:
. Ensure you leave the *POLYLINE* *unselected*.
. In the 'Modify' menu, select 'Explode'
. Click on the *POLYLINE* to select.
. Press ENTER.
. Click on parts of the original shape and notice that you can
select/un-select individual segments of the shape.
The conversion of the complex curves like *ELLIPSIS* can now be achieved
by simply exporting the DXF drawing to the 'old' *DXF R12* file format.
This format does not support shapes like *ELLIPSIS* and exporting to the
*DXF R12* format 'forces' the CAD software to 'approximate' the shape with
line segments that can then be successfully imported into KiCad.
With the DXF open in LibreCAD, export to the *DXF R12* format as follows:
. In the 'File' menu, use 'Save As...'
. Towards the bottom of 'Save Drawing As' dialog, select
'Drawing Exchange DXF R12 (*.dxf)' in the 'Save as type:' selection.
. Enter a different file name, if you like to preserve your original DXF
file.
Here is an example of an DXF import with a board that had several
elliptical segments approximated by a number of short line segments:
image:images/Pcbnew_board_outline_imported_from_a_DXF.png[]
On 09-Sep-15 23:01, Marcos Chaparro wrote:
Thanks a lot Maurice,
so the solution for a complex outline is to draw it directly in
librecad. Its good to know that exporting to R12 is not bulletproof. I
don't see exporting upgrades coming into freecad, or polyline support
coming into kicad either.
As Cirilo told us, it seems reasonable to me that the mcad could
reduce the representation to a more complex (and simpler at the same
time) representation.
A 'cheap' improvement would be to add a warning in the import dialog
saying "polyline not supported". It would narrow down the problem for
the user, right now all the feedback we have is a shape with lines
instead of arcs.
Its interesting that it doesn't totally fail, the import actually
manages to draw lines with the correct start/finish points, it only
loses angle information, see attached.
Marcos
On Wed, Sep 9, 2015 at 6:24 AM, easyw <easyw@xxxxxxxxxxxx
<mailto:easyw@xxxxxxxxxxxx>> wrote:
Hi Marcos and Marco,
please find attached the dxf that I did from scratch using 4 arcs
in LibreCAD
I copied manually the path from palta2.dxf, then exported in dxf R12
The result is fine in kicad and I get a closed path also for Edge
cuts.
in kicad there are 4 arcs
(gr_arc (start 178.564202 123.937945) (end 153.273203 83.107373)
(angle -26.04011298) (layer Edge.Cuts) (width 0.1))
(gr_arc (start 156.68577 88.642784) (end 162.837792 90.749678)
(angle -140.5586133) (layer Edge.Cuts) (width 0.1))
(gr_arc (start 196.246745 102.229265) (end 162.837792 90.749678)
(angle -22.2858684) (layer Edge.Cuts) (width 0.1))
(gr_arc (start 148.500893 105.004408) (end 137.915937 98.354967)
(angle -215.4739741) (layer Edge.Cuts) (width 0.1))
If you search inside palta2.dxf you find POLYLINE that are not
supported by kicad
attached a comparison of dxf files
I suspect that the problem is when exporting dxf from FreeCAD...
I had some trouble with a different board path exported from
FreeCAD...
In FreeCAD you cannot select which version of dxf you want to use,
if I remember correctly...
Maurice
On 09/09/2015 07.43, Marco Hess wrote:
Definitely a problem with the DXF importer I would say as the
resulting
data in the PCB file are just straight line segments:
(gr_line (start 42.68541 28.017695) (end 52.25 35.66) (layer
Edge.Cuts) (width 0.1))
(gr_line (start 27.328145 43.265288) (end 42.68541
28.017695) (layer
Edge.Cuts) (width 0.1))
(gr_line (start 50.392159 49.187096) (end 27.328145
43.265288) (layer
Edge.Cuts) (width 0.1))
(gr_line (start 52.25 35.66) (end 50.392159 49.187096) (layer
Edge.Cuts) (width 0.1))
Marco
On 09-Sep-15 14:58, Marco Hess wrote:
Hi Marcos,
Apologies, but I did not see your original email where you
said you
tried the R12 format alreayd.
I tried it as well and and it indeed seems to do something
strange
with just connecting the end points of the circles or
something.
Regards,
Marco
On 09-Sep-15 14:29, Marco Hess wrote:
KiCad DXF import for those kind of segments don't work
very well. You
need to re-export the DXF in a DXF R12 format.
You can do that easily by opening the DXF in LibreCAD
and then
reexporting in R12 format.
See
http://docs.kicad-pcb.org/Pcbnew/Pcbnew.html#_creating_a_board
Section 6.1.2 and 6.1.3.
Cheers,
Marco
On 09-Sep-15 14:24, Marcos Chaparro wrote:
Seems that is kind of Berzier Curve, not
few arcs. Probably
that shape needs to
split to single arcs before import.
Um, I don't know if its converted to a bezier
curve, but I'm sure I
made it from 4 arcs, see attached.
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References
