The Fundamentals of Sanding Wood Floors 3

Top nail white oak floor first cut with 60 grit.

Step 1: for the big machine, cut the floor at an angle, then straight with the grain.

Step 2: edger rough sanding.

Now that you have finished cutting the floor at an angle the floor should be flat. All you need to do now is run the big machine straight with the direction of the floor. Fundamental: drop the wording “across” or “with” the grain. Technically speaking you run the machine with or across the direction of the floor. This line of thinking will come in handy when you sand patterned floors like herringbone or parquet style floors. Running the big machine with the direction of the floor removes the scratches you put in earlier and makes for a better scratch pattern for the next step.

What is a scratch pattern? When we sand floors, we technically scratch them. Depending on the abrasive grit, the direction of the cut and the type of machines we use, we create a repetitive scratch pattern on the floor. With the big machine the scratch would be linear, but with the edger, the scratch pattern would be circular and the shape of little arcs.

While running the big machine, pay attention not to stop and start at the same spot on each pass, but rather stagger the places where you drop the drum on the floor. Also, don’t start and stop at the same spot on subsequent cuts when you will be doing the fine sanding.

At this point, you are done with flattening the floor with the big machine. The edger will now take care of the edges and areas too small to fit the big machine.

An edger is a sanding machine with a spinning disc that, when properly set up, only touches the floor in one spot (about the size of a quarter.) It is important that you understand this. I can’t tell you how many guys I have met that thought the edger was sanding the floor the full 7” of disc diameter. All you need to remember when learning how to edge is that the edger is spinning in one direction and there is only one contact point on the pad. Put your edger on a flat surface at eye level. Look at the bottom of the pad. The pad should only be touching the surface at the front of the edger somewhere between 11:00 and 1:00 o’clock, depending on how you adjust it.

How to rough sand a floor with the edger

The edger performs two functions; to flatten the floor and to refine the scratches, just like the big machine. Looking down at the edger with the wall in front of you, start moving across the floor starting with the wheels on the flat surface which was already cut by the big machine. Move the edger from left to right, back and forth, advancing it toward the wall in small (1/2”) increments. If you are doing this correctly, the entire area sanded should be flat. This step is similar to the big machine’s first pass going at an angle. After the floor is flat, use the edger to pull the scratches away from the wall, remaining mindful of the direction of the scratch is being placed in the floor.

With the rough sanding now complete set nails if any are exposed and fill the floor as needed.

When filling the floor, you have to consider the following regional and jobsite specific options:

  • Full trowel the floor versus spot filling
  • Use off-the-shelf filler or make your own

We will discuss fillers on the next blog post.

Avi Hadad is the owner-operator of Avi’s Hardwood Floors in the San Francisco Bay area. He can be reached at avi@avisfloors.com.