Problem with Elliptical parts when saved as a dxf

Discussion in 'SolidWorks' started by Simcoe Warrior, May 29, 2007.

  1. I am having some difficulty with any parts that are elliptical. For
    example I have a piece of glass
    in the shape of an oval and our glass cutting software uses a .dxf
    file to cut the shape. When I
    saw the part to an SW draing and then export it to a DXF, the ellipse
    itself turns into a
    bajillion line segments which cause havoc by creating a bajillion
    lines of code in the
    cutting software.

    Has anyone else encountered this or found a way around it?
    Simcoe Warrior, May 29, 2007
  2. Simcoe Warrior

    TOP Guest

    I think you will find this a common refrain about ACAD translations.
    The bajillion lines is a poly line, and AUTODESK inovation that is
    probably being abused just a bit here.

    TOP, May 30, 2007
  3. Simcoe Warrior

    Cliff Guest

    Just one dumb question: how do you expect te output code to
    interpolate an ellipse, anyway? Does the machine have a
    "Cut ellipse" command?
    Worst case: create the ellipse in AutoCAD from it's major & minor axes
    (or other parameters) in SW ..?
    Cliff, May 30, 2007
  4. Simcoe Warrior

    Cliff Guest

    I don't suppose exporting it as IGES ... ?
    Cliff, May 30, 2007
  5. Simcoe Warrior

    Ronni Guest

    Rule of thumb: Save output files in the oldest possible format.

    R12 or R13 Autocad dxf-formats makes much less mess than if you save
    them as R2000.

    We had the same problems here with ellipses changing form if you save
    them in the newer formats.
    But also texts and hatchings seems to go wrong in teh newer versions.

    To sum up, we save every dxf as a R12 :)
    Ronni, May 30, 2007
  6. Simcoe Warrior

    John Guest

    To avoid the multi segment issue when saving a DXF you must use R13 or
    later format. AutoCAD did not add support for true ellipses until
    R13. Prior to that they were represented as polylines using many
    straight line segments.
    John, May 30, 2007
  7. Simcoe Warrior

    Ronni Guest

    Nice info thanks, that will for sure become usefull to me later :)

    But teh choice of version comes down to what you need the dxf for.
    We use it for our CNC machines (Laser etc.), here the best results
    have been from the R12 version.
    It seems to me like you said that it turns the ellipse shape into
    other (and more of course) line types. Which is suited for our CNC
    machines, or in most cases actually a better choice (most our machines
    are more than 5 years old so they dont support ellipse aswell).

    But my message is still... use the oldest version that suit your needs.
    Ronni, May 30, 2007
  8. Simcoe Warrior

    Alan R Guest

    If you want to use R12 to have line segments for CNC purposes, go to:
    Tools|Options|Document Properties|Image Quality|Wireframe and high
    quality HLR/HLV resolution|
    Increase the quality to give the desired resolution of the line
    segment resolution of your dxf splines and ellipses.
    Alan R, May 30, 2007
  9. What version of SW are you using? I do not have that capability in
    Simcoe Warrior, May 30, 2007
  10. Simcoe Warrior

    thestew Guest

    I am running 07 but I am pretty sure you could do it with 06.
    thestew, May 30, 2007
  11. Simcoe Warrior

    J. Nielsen Guest

    ....or just trace the lines with a few 3-point arcs and delete the lines

    An "ellipse" made of only six arcs will do fine for most practical
    purposes. Hell, even an oval of 2 x 2 arcs would probably do
    (unless, of course, a certified engineer has to okay the part)

    <waves> Hi Cliff. <g>
    J. Nielsen, May 30, 2007
  12. Simcoe Warrior

    Alan R Guest

    This has been available for several versions. I remember using it
    about 5 years ago when I had a similar issue with spline in dxfs.
    Alan R, May 31, 2007
  13. Simcoe Warrior

    Cliff Guest

    They still probably want to break it up into little linear moves <g>.

    <waves back> <G>.
    Cliff, Jun 1, 2007

  14. I never noticed this before, but under "options" when you export as dxf or
    dwg there is a box for spline export options, allowing you to choose to
    export splines as splines or polylines. Does that have any effect on an

    Jerry Steiger
    Tripod Data Systems
    "take the garbage out, dear"
    Jerry Steiger, Jun 1, 2007
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