Here is my first test print. The good news is that the ultimaker did make it to the end of the print (17 hours!). The bad news is that all the lower surfaces (facing towards the center of the earth) are somehow jagged and fibery. I am a total noob, so I assume that I did something stupid that can be immediately corrected with a trivial setting. I note that no support material was used - although I had expected it to be utilized.
The test STL file is here: https://www.thingiverse.com/thing:3