More information: I'm able to draw now, but the drawings are mirrored, rotated 45º (I'll go read the posts that talk about that), and the position drifts.
Here's an example of the drift:
I drew a series of concentric circles in inkscape, with a few radius lines. It looks like this:
I converted the file to gcode using the inkscape plugin. Now, this is how it's plotted:
The first circle (outside) is not too bad, after that a straight line is draw, and after that the remaining circles do not close properly. The misalignment becomes evident at the center of the circle, where the lines do not cross at the center.
What can be the error? I'm uploading the gcode, in case someone would be willing to give it a try in their own plotter.
Thank you !