Problem with Elliptical parts when saved as a dxf

May 29, 2007 9 Replies

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?



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.

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I have encountered this issue many times. Try this. Open your drawing do a file save as, pick .dxf from the drop down, hit the options button just below the save and cancel buttons, export options screen will appear, look at the spline export options, make sure you check export all splines as polylines. Good Luck!!

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.

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.

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.

What version of SW are you using? I do not have that capability in Sw2006.

I am running 07 but I am pretty sure you could do it with 06.

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.

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 ellipse?

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

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