Looks really cool ...

Up to now I only knew these programs for virtual origami.

Roland

Hello banan666.

Just my 2 cents ...

In my personal opinion you have four possibilities:

1.) try to live with situation given.

2.) export to dxf and then correct (that means delete and draw new ones) all arcs and
circles in your drawing/file
For that you have to use a 2D CAD-Program like for example LIBRECAD (http://librecad.org/cms/home.html) .

3.) since DOUBLECAD (http://doublecad.com/) works with Sketchup maybe you could give it a try
and export from Sketchup to DOUBLECAD and then to dxf.
Maybe that will give you perfect arcs ?
Since DoubleCAD XT is free for personal use you could give it a try.

4.) If you want to keep 3D abilities and want to have "real" arcs and circles,
maybe you should think about investing in a NURBS Modeller like
VIACAD (http://www.punchcad.com/p-9-viacad-2d3d-v8.aspx) or TurboCAD or something similar.

Roland