Improperly exported to DXF


Hello, my SU file is not being exported properly into DXF. I’m using SU 2018 Pro, and export my drawing using parallel projection and as a 3D model. When i view my DXF file in draft sight (required to run CNC machine) it shows open or sometimes overlapping corners. In SU these corners appear perfect. What am I doing wrong?


Better to post some images of the problem.


ok here are three screen shots…


The bottom one appears perfect in SU, and then in Draft Sight upon zooming in, the corners are open in this case. CNC machine does not allow this


Within SketchUp, when you draw a circle or circular arc, it is actually represented as a sequence of straight edge segments with associated “metadata” containing the mathematical parameters of the circle (center, radius, plane, arc ends, etc.). Only the endpoints of the edges lie on the mathematically exact circle; the edges themselves are chords of the circle/arc. If you subsequently draw another edge that intersects the “circle” anywhere except at one of the original segment vertices, the intersection therefore does not lie on the mathematically exact circle.

But when you export to 3d dwg/dxf the exporter replaces the segments with a true circle (because dwg/dxf has true circles). The intersection with the other edge (the other edge’s end vertex) is on SketchUp’s segmented representation, not the exported true circle so you get the gap you have seen.

The workaround (which is admittedly clunky) is to draw the other edge first and then draw the arc starting with a point on that edge (and continuing to a point on another edge at the other end if appropriate). This technique assures that there is a vertex of SketchUp’s representation at the point where the edge and arc meet. Alas, other edges drawn to points along the arc will still show gaps unless they also hit vertices. You can draw the arc as a series of arcs to work around this, but that obviously gets tedious.


Thank you will try this now.


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