Inspiring work there Timtoo. One of my aspirations is to make a really satisfactory astrolabe. I have SVC files for the engraving, though somehow fusion 360 scrambles them up a bit . I also fix clocks from time to time, I hadn't thought my cheapo Chinese cnc would e up for the job - just playing with the technology at the moment. I got the point about brass, and the speeds and feeds - what would be a good set to start with to experiment ? I'd figured a slow feed rate and my fastest (8000 rpm) rotation would be a start