Types of Floor Sanders
There are generally two types of floor sanders: orbital and drum sanders. Drum sanders are the sanders typically used when refinishing floors. They do the best job at the best possible speed. There are however, places where drum sanders are not the best choice. Drum sanders consist of an 8" wide drum that has a 20" long sheet of sandpaper locked into it's jaws. This rotating drum does an excellent job of removing old finishes. The biggest drawback to a drum sander is that if you have to sand at right angles to the wood grain it can leave sanding scratches in the floor. In this case the orbital floor sander may be a better choice.

Orbital floor sanders consist of a 12" x 18" sanding pad that oscillates back and forth in an orbital motion. This ensures that no repetitive sand scratching will occur so it's safe to use for cross grain sanding. If you have a narrow hallway, pantry, or entry where the flooring is run at the wrong angle to use a regular drum floor sander the orbital sander would be a better choice. Because the movement of the orbital sander's paper is minimal compared to the drum sander it will not leave sanding marks. The biggest drawback to the orbital sanders is that they are much slower than the drum sanders. This needs to be repeated: "They are slow compared to the drum sanders." Drum type floor sanders are 10 times more popular than orbital floor sanders. If you have a job that can be handled by a drum sander you will be much happier using that style of sander. Only use the orbital sander for those jobs that are not best suited for the drum sanders. If you have any questions about which is right for you please give us a call and we'll be happy to discuss your job with you. The following tutorial applies to drum type sanding operations.

What You'll Need
There are a few items you'll need to sand your hardwood floor. While the larger sanders can be rented, you will also need to purchase a few small items as well:

1. Floor Sander, Drum Type
2. Floor Edger, Disc Type
3. Vacuum Cleaner, Preferable a Shop TYpe
4. Sandpaper (Fine, Medium, Coarse)
5. Hammer
6. Nail Set
7. Pry Bar
8. Hand Scraper or Detail Sander
9. Dust Mask, Safety Glasses, Ear Plugs

Prep Work

1. Remove the quarter round molding or baseboard if at all possible. This ensures that you can get as close as possible to the wall to achieve the best look possible. Use a small wooden wedge between the drywall and pry bar to prevent from damaging the drywall.
2. Repair or replace any loose boards by gluing and nailing.
3. Countersink any nail heads with your nail set. If the nail heads are not sunk down into the wood they will tear your sandpaper as you sand.
4. Vacuum or sweep the floor.

Sanding Old Floors

Note: If you are finishing a new floor, skip the coarse paper and begin with the medium paper unless you have some severe variations in thickness between the different flooring boards.

1. For the first pass begin by installing the coarse paper (#20-3-1/2 grit) on the sander. Curl the edges slightly on the paper (being careful not to bend them too sharp so that the grit cracks) so that they will tuck into the slots on the drum more easily. A paper folding guide is located on the very front of the floor sander for this purpose. Back off the two cam levers on the drum 1/4 turn each to open up the paper slot. The cam levers are in a somewhat half round configuration so when the two flats are facing each other it will be less difficult to insert the paper into the slot. You can look into the slot to verify the position of the pinch rollers before continuing. Each roller needs to be rotated 1/4 turn to hold the paper. Take the wrench supplied with the sander and tighten the cam roller on the left side as you are facing the machine from the front. This is the cam opposite the belt guard. There are arrows on the square part of the cam rollers that indicate which direction you need to go. Then, after the first cam has been rotated 1/4 turn, rotate the second cam 1/4 turn as well. With coarse paper it will take some tugging to get it to go that final 1/4 turn. If you don't have the paper clamped securely in the jaws it will tear when you begin sanding. Also, be sure that it's tight on the drum and not a loose fit or else it can tear as well.

2. Divide the room into thirds. Line up alongside one wall with 2/3 of the room in front of you. Turn on the sander and gradually lower the sanding drum to the floor and immediately begin slowly moving forward. When you get to the end of the wall lift the drum. If you sit in one spot you can sand down too far, so the secret is to keep it moving. Then back up to your starting position and make a second row, being sure to overlap the rows by about 4". If the floor is severely loaded with varnish or paint you may want to sand backwards from the end of the first row rather than return with the drum up and not sanding. If small amounts of the old finish remain, don't worry about it. You can get that on the second pass with the medium paper. If there's a lot of old finish left you may want to run the coarse over it a second time to get it cleaner. The sandpaper doesn't wear out as much as it plugs up and the medium paper has less ability to retain old varnish so it's best to get the most mileage out of the coarse sheets before going to the medium.

3. Once you have worked yourself over from one side wall to the other you can turn the sander around and do the exact same thing in the opposite direction. When finished you'll have a rough sanded floor.

4. Before proceeding with the medium grit it's best to bring out the edger now. Mount a 7" coarse disc to the edger and run it alongside the wall to remove the varnish and blend it in with the main floor area. It's easier to edge sand now rather than waiting until the very end after the drum sander is finished. Be sure to keep the floor edger moving while sanding. You'll achieve better results by keeping it moving in large sweeps than slowly feeding it along. At this point may want to scrape or sand the corners as well. More on this later.

If the boards are somewhat cupped you may need to do this first sanding at a 45-degree angle to the grain. This will help to sand the area down in the saddle of the cupped board.

For the second pass, repeat the above procedure using the medium (36-2 grit) paper. You probably won't have to do any 45-degree sanding at this point unless your boards are seriously cupped. Before you begin, vacuum the floor. After you are finished, vacuum again. If you need to fill any cracks up with wood filler, do it now before you begin the final finish sanding.

What About The Corners?
Face it--round edger discs don't fit well into square corners. If you need to remove varnish from them you may be able to do it with a paint scraper. A better choice is our Detail Sander to get into those hard to get areas, like corners and underneath toe kick spaces. Its orbital action is both fast and safe and will save you lots of time.

Finishing Touches
When all done you should have a sanded floor that's ready to accept new polyurethane or any other finish of your choice. Some pros do like to go one step further and use a floor polisher machine with a fine grit sandpaper or screen. We find this to be a somewhat hard to handle setup and it doesn't get into corners because of the 17" diameter disc. A better choice for that would be the Orbital Floor Sander,  which is easier to handle and has a 12" x 18" rectangular pad that gets into corners better. It's available with extremely fine sandpaper or screens if desired.

Helpful Hints
Floor sanders draw power. You'll need a 20 amp circuit to run one. Fifteen amps are marginal and you'll probably be spending way too much time resetting tripped circuit breakers. While there are dust bags, there still will be fine airborne dust that gets everywhere. Remove hanging pictures and drapes prior to sanding. When you are done sanding vacuum the walls to prevent drafts from blowing any clinging dust onto your wet varnish. Wear clean soft shoes, like sneakers, to prevent leaving black marks on the floor. Hang plastic drop cloths over open doorways to help contain airborne dust.

When you are finished you'll find it really wasn't as hard as you thought and you can now take pride in your newly refinished floor. It will be around for a long time.