It took Bert three days, but the 2nd story floor is looking good.  It was a little more work than expected, because of the layers of wax that gummed up the sandpaper instantly.  We eventually had to use a belt sander over the entire floor, to get rid of the wax, and then use the fancy floor sander after that. 

 floor sanding 01

floor sanding 02

floor sanding 03