How to Use a Drum Sander

Drum sanders make quick work of sanding down hardwood floors. These machines can be affordably rented by consumers, but must be used properly to achieve good results. Learn when and how to use a drum sander, what sandpaper to use with a drum sander, and how to check if your hardwood floors can be resurfaced with a drum sander.

What Is a Drum Sander?

A drum sander is a heavy walk-behind power tool used to resurface hardwood floors.

Drum sanders are powered by electricity. A motor in the drum sander housing spins a rotating, sandpaper-covered cylinder called the drum. A lever connected to the handle of the drum sander is used to strategically raise and lower the drum, controlling its contact with the floor below.

Drum sanders remove a significant amount of material with each pass, so over-sanding is a constant concern when working with these machines.

Using a Drum Sander

Use a drum sander to revitalize your old and tired hardwood floors.

1. Confirm that your surface is suitable for drum sanding. The hardwood floor must have at least ⅛” of exposed wood (above the tongue-and-groove joint between planks) in order to be drum sanded. See the section below for how to check the thickness of your floor.
2. Clear the area to be sanded. Remove all belongings from the room. Sweep the floor. Remove or hammer down any protruding fasteners or anything that might obstruct the drum sander.
3. Buy sandpaper. You will need sandpaper in the following grits: 60, 80, 100, and 120. Bring the dimensions of the surface you will be sanding. Ask the shop attendant for advice on how much paper to purchase, and confirm that they will buy back unused sanding paper.
4. Map out your sanding pattern. If you run the sander over the same area too many times or hold the sander in place for too long, you will gouge your hardwood floors. Put some thought into how you’ll move across the floor before you start sanding to avoid over sanding.
5. Master the sanding technique. See the section below for tips and tricks on how to maneuver the drum sander without damaging your floors.
6. Flatten the floors. The ‘first cut’ when resurfacing floors is done with a very coarse grit sanding paper, moving the sander back and forth at a 45 or 50-degree angle to the planks. This eliminates the difference in thickness between boards, giving you a flat and even surface that is clear of old finish.

Move the sander slowly but steadily across the surface.

9. Empty the dust bag. The dust bag attached to the drum sander fills up with removed material as you sand, and you will need to stop regularly to empty it. Never leave the drum sander running while you empty the dust bag.
10. Smooth and remove scratches. Move up to a less coarse grit for the second cut. This pass will remove the scratches from the previous sandpaper and smooth the surface. Sand with the grain, moving parallel to the boards.
11. Prepare for finishing. A final pass is necessary to prepare the hardwood floor for finishing. Use medium-grain sandpaper for this step and sand in parallel, overlapping passes, in the same direction as the grain.

Drum Sander Technique

Using a drum sander without gouging your floors requires a refined technique. Make sure you understand how the machine works and can manipulate it appropriately.

• Don’t attempt to sand corners or areas close to the wall. The drum sander is not made for this purpose. Later, you will finish these areas with handheld sanders.
• When you are ready to sand, start moving the drum sander backward as you gently lower the drum to make contact with the floor. 
• As you are reaching the end of the sanding pass, gently lift the drum off the floor using the lever.
• Rock the drum sander forward again and reposition it for the next pass. 
• Move the lever only ¼” each time. Avoid slamming the drum down on the wood. Ideally, the drum will take off gently and land without a bump, similar to an airplane.
• Sand at a 45-degree angle when flattening floors.
• When smoothing the planks and preparing them for finish, sand in the direction of the grain, parallel to the boards.
• Overlap each pass by half the width of the drum.

Can I Use a Drum Sander on My Hardwood Floor?

You can use a drum sander on your hardwood floor as long as there is at least ⅛” of exposed wood. It may be possible to resurface hardwood floors with less than ⅛” of exposed wood, but you should get a professional opinion before attempting this risky project.

Resurfacing floors that are too thin causes splintering, and total replacement may be necessary.

Most hardwood floors are made from planks three-quarters of an inch thick and can be refinished six to ten times before needing replacement. Some older homes, such as those built before 1920, may have hardwood floors that are much thinner.

How to Check Thickness of Hardwood Floors Before Drum Sanding

If you don’t know the history of your hardwood floors, you can check how much exposed wood is left using a stiff piece of paper.

1. Find a crack. Inspect your floors until you find a decent-sized space between two planks.
2. Insert a stiff piece of paper. Regular paper will crumple, so use something stiff like a birthday card or business card. Push one end into the crack, stopping when it hits the tongue-and-groove joint that connects the planks.
3. Make a mark on the paper where it meets the top of the plank.
4. Remove the paper and measure the distance from the edge of the paper to the mark. This measurement tells you how much exposed wood remains on the hardwood floors. From there you can decide whether or not it is appropriate to resurface them with a drum sander.

What Grit Sandpaper for Drum Sander? 

You will need at least three different grits of sandpaper to refinish hardwood floors with a drum sander.

• For a slightly worn floor, start with 36-grit sanding paper. Old or severely damaged floors might require an even coarser grit, such as 12, 16, 20, or 24.
• When the floor is clean and flat, you can switch to 60 grit sanding paper. 
• A final pass with 80 grit sanding paper is necessary to prepare your hardwood floor to accept finish.
• You may choose to continue sanding for a smoother finish, using 100 or even 120 grit sanding paper.

To eliminate your sanding marks as you go, never skip more than one grit level. For example, if you start with 12 grit sanding paper, don’t jump to 36 grit without using 20 grit paper first.

Conclusion

The best drum sanders are used to resurface suitable hardwood floors, refreshing their appearance and preparing them to accept a new finish. Using a drum sander requires attention and technique. Several passes with different sandpapers are required to refinish a hardwood floor. Not all hardwood floors can be resurfaced with a drum sander.