Here is how to sharpen ice auger blades with sandpaper: Take a flat smooth surface like a piece of heavy glass, or even better, a ceramic floor tile. Again, you will want three different grits of sandpaper ranging from coarse to ultra-fine.  It may be best to have three ceramic floor tiles, one for each grit of sandpaper. The sandpaper should be the wet/dry kind. Now take each grit of sandpaper and cut a piece that is a little smaller than the tile. Tape down the sandpaper to each tile so that it is smooth, tight, and without wrinkles.  Now wet your blades using the nearby bucket of water and follow the same exact process that you would use for the whetstone. The sandpaper simply replaces the whetstone.