First off, do NOT use a drum sander. These things will leave the floor uneven and you'll be able to see it in the reflected light off the floor. If you've never sanded a floor before, get one of the random orbital floor sanders that have 3 or 4 discs on the bottom. You can rent them at Home Depot. It's virtually impossible to mess up your floor with these, and they leave a nice even finish.

However, you've got some prep work to do before you start sanding. You need to face nail any loose or creaky boards with barbed nails. Those gaps need to be filled, and they need to be cleaned out before you fill them. My recommendation would be a small fine bristled brass wire brush. Put the vacuum next to it as you brush so the crap doesn't fall back down the gaps.

Now you need to fill the gaps. The only thing you should consider using to fill these is a product called Woodwise. It's specifically meant for hardwood floors and it expands and contracts at the same rate as the wood, so it's unlikely to crack or work its way out. It can be thinned with water and troweled over the floor so it flows into the gaps better. You can be messy here, as the sander will knock down any mess, just make sure it gets pushed deeply into the gaps. It's a GREAT product. Do not skip this part, it's almost as important as your sanding.

Now, you get to sanding. Use the random orbital I mentioned above. I would never use a drum sander on a floor unless it was going to be gone back over with one of those big disc sanders. Looking at your pics, I would start with 40 grit to get all the boards an even height. You MUST vacuum when changing grits, because there will be 40 grit sand particles on the floor from the previous sanding and it will cause scratching. Make sure you get the edges and corners with a small handheld random orbital. For grits, I'd go: 40, 80, 120, 150, 180, then hit with a pad (looks like Brillo material)

If it's anything other than oak, I'd continue up the line and get as fine as you can. In maple and birch, you can bring out the "fire" by going to 1500 or so (do a search for photos of the back of a violin). No hardwood floor installer is going to do this for you, so you've got a chance to do something really cool and relatively unique with the floor if you want to spend a lot of time sanding.

Now, you need to finish the floor. Are you going to stain it? If so, you've got 3 options:

• Water based stain (must use if using a water based poly)

• Oil based stain (must use if using an oil based poly)

• Dye - Comes in 1-2 oz bottles, and you mix with water or SLX alcohol

I prefer dye. It brings out the grain like nothing else, and I mix it with alcohol so it doesn't raise the grain. You can buy this at high end woodworking stores. If you go with stain, try to buy the same brand as the finish you are putting down to make sure they are compatible.

For the finish, I prefer Bona (specifically Traffic). It's a water based poly, and is probably the best non-factory applied coating you can put on the floor. It doesn't stink the place up like oil based, and it won't yellow over time like a lot of other coatings will. Don't buy anything from big box stores, they all sell crap for finishing floors. Here's the problem, you probably cannot buy Bona Traffic because most places won't sell it to you unless you're a licensed floor contractor. But, Bona does make a non-catalyzed finish that is probably second best that you can buy. Find a hardwood flooring supply store and buy your stuff there. So, for finishing, you'll need:

• dye or stain if using

• Bona water sealer to prevent grain raise during the poly coat (1 coat of this)

• Bona Traffic or their non-catalyzed finish (2 coats)

The process of applying the finish is pretty straightforward. You POUR it on thick along the far edge of the room, and use a wide foam squeegee to pull and even coat across the floor towards you. You need to have it thick enough to self level, and if you're using Traffic, you have to work fast because you don't have long before it hardens. When your puddle that you're pulling starts to run thin, pour another line where you left off and continue.

Source: After being disappointed in the work that I hired out on 1700 sq ft of custom milled white birch, I learned everything there is to know about doing hardwood floors and started doing them myself. Most of what I've learned is from people who work in the industry and do it for a living. I've done my own, and a few for friends. I just moved and now have about 2200 sq ft of maple that needs refinishing, so I'll be doing it again sometime in the near future.

The biggest problem I see with DIY hardwood floor finishing, is that people read an article online that says rent a drum sander and buy some poly from Home Depot. There's more to it than that, and if you follow those simplistic instructions, you're gonna end up with a refinished floor, but it's not going to be very nice, and it probably won't last long.