Thanks Charlie, I know about the difference between 2d and 3d DXF export. The problem is different.

In the attached image you can see what the problem is I encounter. The DXF export does generate true arcs (non segmented) code, so far so good, but...

In both the DXF to G-code translators I use (free ace converter and USB CNC, the last one a professional program), the G code based on a DXF file generated by sketchup pro 8 results in a mirrored output.

Thanks Dave R for the quick reply.
So having multiple installs is possible, they install seperately, good to know. What happens if you uninstall v2016 pro trial version, are you absolutely sure that will not in any way compromise the v8 Pro installation? Is there nothing 'shared'? (Windows 10)

Anyway, what I'm really asking is, if someone who is an experienced DXF exporter of models (with arcs), can tell me about the reliability /accuracy of DXF export in v2016 Pro. Are there problems to be expected with arcs or otherwise?

DXF export would be my work-around solution. The no1 solution for me (and maybe others?) would be if anyone could get the path2gcode.rb plugin to export non-segmented arcs (not exploded or cut off) that translate to G02 /G03 i j format arcs in g-code. But I realise that is a long shot

Hello,

I use sketchup pro 8 to model and then create 3d (not 2.5d) cnc G-code paths. There is an excellent and elegant plugin called path2gcode.rb that works perfectly, just like I want; it simply creates g-code from any line-path with a start and end, startpoint is always at the highest z value of these two ('blue' in Sketchup) and then it works the path down to the end. It is straightforward, predictable, reliable, fast and light. But....

Sadly, this plugin does not generate true arcs, with G02 G03 I J. If the plugin would do that, it would really be perfect. (anyone? I can imagine this is a nice challenge for the programmers out here...)

As a workaround to get true arcs with G02 G03, I tried to use the sketchup DXF 3d export and let the cnc software (USB CNC controller) generate G-code from that DXF.

The DXF export of Sketchup Pro 8 turns out to be unpredictable. It tends to flip the bulge of G02 G03 arcs inward /outward, especially when arcs have negative x or y coordinates, which means I would have to correct these manually... It may have other issues I am not aware of yet. Anyway, for complex designs I am planning now it is useless, the DXF exporter of v8 Pro simply messes up the model too much.

I'm considering upgrading to v2016 pro, IF it exports DXF correctly. Does it?

PS: Maybe you wonder, why not use the trial version of v2016 and test it?... Well, I'm affraid it will give conflicts when the trial licence expires and I remove v2016. I do not have an install backup of pro 8, and Trimble does not provide backup installation files of the pro 8 version on the download page anymore.

thanks for reading