Hi Giorgio, great stuff! The maximum density of a pixel is controlled by the pen tip width. Is the width of the pixels ok? I mean, so they appear in the right place, and the gondola can otherwise move all around the paper?

You can calibrate your pen tip size by doing a pen width test. In the new software, there's a button for this on the setup page. What it does is draw a series of dark pixels at the current row size, each one with a different sized pen tip.

There's a bit of description of this at the bottom of this page:
http://code.google.com/p/polargraph/wiki/SoftwareControllerGuidev2
that describes how to use it for the old software. I haven't wrote anything about the new controller yet, but it'll be the same except that you can change the values directly in the program rather than editing the properties file manually.

Good luck
Sandy Noble