Exporting DXF files containing arcs

[Anonymous]

I am only an occasional and limited user of Fusion 360, but it seems to have changed the way it exports arcs in DXF files.  It now converts almost all arcs to polylines.  I believe my CNC will run more efficiently if I use arcs rather than many line segments. Is this new behavior ?   Any way to force it to export arcs as ARCs in DXFs?

[HughesTooling]

Sound like what you think are arcs are splines, perhaps you've projected an arc that's not perpendicular to the sketch plane or the edge of an angled face\hole.

Mark

[HughesTooling]

Something you can try is using the inspect tool, select one of the arcs, the tool will list it radius, diameter and centre point. If all you get is it's length then it's a spline.

Mark

[Anonymous]

Thanks Mark for pointing me to the inspect tool.  It did help me verify that Fusion is using arcs for the drawings  but after looking at many DXF files of trial drawings discovered that when it exports arcs in DXF files, they are transformed to polylines  when the arc is part of a closed line.  I did not know that the polyline entity includes a bulge parameter between vertices which of course allows an arc to be derived.  So my problem is solved, in that I will now be able to break up the polyline into lines and arcs. It does seem strange that lines and arcs used to create the drawing are not simply exported as part of the DXF file.  I thought polylines were used to describe splines in DXF files.