reply to Ken
Re: Sanding/refinishing oak floor a DIY job?
said by Ken:I think your post is a great place to begin a real discussion of what is involved. I want to start by listing the different sanders which can be used for floors and their abilities and liabilities.
I think there is some confusion here on using an orbital sander to do the entire job.
1) Professional Edging Sander -- this is not an orbital sander, it is a disc sander. Disc sanders in general are only useful for rough work. One of the main problems is that no matter which direction you go with it you cannot control it to the extent that you can sand with the grain. As this sander is used with course grits of sandpaper it can gouge and create damage in inexperienced hands. Even in professional hands, there will be some gouging and cross grain scratches visible under close examination.
2) Drum Sander -- Main tool of the "professional" flooring installer / re-finisher. Main tool for one reason -- it removes a lot of wood very fast. Drum sanders gouge very easily and create an uneven surface even in professional hands. They are great for evening out a surface but are not a finishing tool and should not be considered as one. Must only be used with the grain. It is surprising how much wood is removed in a short period of time with this tool. It is equally surprising how few times a floor can be re-finished when sanded by this tool due to the massive amount of wood removed during sanding.
3) Belt Sander -- I'm not sure if there are any large, floor type of belt sanders around but they would be more controllable than a drum sander if there are any. Still fairly aggressive and must be used only with the grain.
4) Orbital Sander -- The Square-Buff sander posted by another member is an orbital sander. Orbital sanders can have either round or square pads. The sanding pad moves in a small, orbital motion. Even on the large floor sanders, this orbital motion is only about 3/8" in diameter. While this sander is quite un-aggressive, it is also quite slow to strip a floor down to bare wood with. On the other hand, there is no gouging and if you run this machine over a floor sanded by a "professional" using a traditional drum and edging sander, you will discover just how uneven they left your floor. This is a great tool to use for screening a finished floor prior to adding another coat of finish. You can use sanding screen with it (available in many grits -- same type of screen used for drywall sanding).
5) Random Orbital Sander -- This is the type of sander most of us have now in our small tools drawer. It is also one of the best floor sanders for the DYI floor re-finisher. While I'm not sure if the three and four pad sanders which Ken posted pics of are of this type, there is one I can vouch for. It is the Varathane ezV sander. This sander has three 8"disks with two rotating in one direction and one in the other. These disks are mounted on a larger rotating disk which rotates slowly. The result of the dual rotation motions is a random orbit. This type of sander is extremely forgiving and will not scratch or gouge the floor. At the same time, it is more aggressive than the orbital sander. The ezV is also quiet and has a very good dust pickup system resulting is a pleasant experience for the operator and only minor dust in the house.
Choosing the right tool for the job is very important. Knowing it's strengths and weaknesses even more so. This post doesn't really address the needs of the OP but it seemed a good time to discuss the various options available for use when refinishing a wood floor.