Grit and time will depend on condition of the floor and the species of the
wood that you are dealing with, not to mention the number of bump-outs,
obstructions, heat grills and other things you have to work around.

"Davej" wrote in message
...
Went to Home Depot yesterday and see they have two sanders for rent.
One is a belt sander and the other is a large orbital. Both are
intended for floors. I just need to take the varnish off an old floor.
Is the big orbital the best tool for this? The room is 15x20ft. Any
idea how long this will take me or suggestions on the grit to begin
with? Thanks.