Unless you plan to sand many floors in your lifetime, the best choice for do-it-yourself floor refinishing is the random orbital sander. Sure, it may take longer to remove old finishes than it would with a drum sander, but you don’t need a lot of experience to operate random orbital sanders and most importantly, they are less likely to permanently damage your floor with by causing grooves or valleys that are impossible to fix.
I have found that Clarke-American random orbital sanders are the easiest to use of the models available for rental at most home centers. Avoid renting sanders with 6″-diameter circular orbital sanders at the base. Often coming the brand name U-Sand, these sanders are as readily available as Clarke-American but far more difficult to control. And because the sanding surface of U-Sand models is relatively compact, they take longer to do the job. Making matters worse, four-disk units like the U-Sand offer little or no padding under the disks, so the abrasive does not lie flush to the floor, further reducing the available sanding area while slowing down the process even more.
Just because you’ve rented a random orbital machine doesn’t mean there’s no need to be careful. Be sure the sander is running at full speed when you lower it to the floor. It is also important not to move the sander too quickly across the boards. Above all, remember to never turn the machine off while it is resting on the floor. For any of these different mistakes, the consequence is the same: circular scratches on the floor surface. They may not be very noticeable as you’re sanding, but they’ll definitely show up when you apply the finish.
For a primer on using random orbital sanders, view our slideshow The Best DIY Floor Sander.