Is it possible to sand a 200 sq. ft. room (oak floors) with a 3X18 belt sander?

sure, just dig in

there are big machines that do that. They look like a vacuum sweeper but have the sander on the end of it and contractors are trained to get an even sweep from one side to the other of their swing. If you're using a small sander then you may get ripples in the wood. And, it would take them a lot less time to get this project accomplished. And they can clean up the sawdust quicker. So I'd say this is a job for a specialist. If I were doing that I'd call a flooring place and ask them if they know of a contractor that does sanding.

I hope you have a lot of time and are very careful. Using a 3" wide sander is probably going to leave grooves. That's why professionals use the WIDE belts. They use the smaller sanders for edges, etc. I did a very small area with a 3" sander (about 1' wide x 6' long) and it took a while to get it right.

Good Luck

My husband and I sanded our whole house (which has 60 year old oak floors) with a belt sander we rented from a rental company. The sander had a belt that was about 14" wide, and a vacuum on it to control the dust the sanding made. The machine is quite heavy (looks like a vacuum), but it was easy to use. They gave us all different grains of paper that we were going to need to use, a demonstration on how to use it, and then a video from start to finish.

We did the floors in one weekend (sanding) which is about 1400 sq. ft. and after we got them finished they look wonderful. We, of course, had to pat ourselves on the back....lol.

It is possible but stupid. It is too small for such a large area and you will end up with uneven areas.

Hire a proper floor sander.

Belt sander is not good- you could rough the suface well enough to get rid of imperfections and then refinish, but use an orbital.

yeah, but you can also make one heck of a mess if you don't know what you are doing