Load your rented sander with a 40-grit sanding belt.
Start with the sander with the belt raised off the floor. For most models, there will be a lever to do this. Let the belt get up to full speed before dropping it to the floor.
Move the sander forward and back at medium speed in a direction diagonal to the direction of the floorboards. Work your way over the whole floor, letting the sander take off most of the top layer of wood.
Vacuum up the dust, using a vacuum cleaner with a bare-floor attachment.
Reload the sander with a 60-grit sanding belt. Sand the floor in the opposite diagonal direction as before, again going forward and back at medium speed, taking off the rest of the top layer of wood. Vacuum up the dust.
Load the sander with a 100-grit sanding belt. Run it in the direction of the floorboards to smooth out the surface.
Vacuum the floor. Do a final sanding with a 120-grit sanding belt in the direction of the boards to get it completely clean and smooth. Vacuum thoroughly. The floor is now ready for refinishing.
Things You Will Need
- Drum sander (rented)
- Sanding belts in 40-, 60-, 100- and 120-grit abrasion
- Vacuum cleaner with bare-floor attachment
- Safety goggles
- Ear plugs
- Use a handheld rotary sander to get into the corners where a drum sander can't reach.