And what will you do when summer humidity comes and forces the wood out of the joints? Wood expands and contracts and the only way to stop that is to perfectly maintain temperature and humidity. In other words, it can't be stopped except inside a museum. In real life, old homes have gaps between their floor boards. It's part of why people like old homes.

Woods going to expand and contract. But it wont close a 1/2 gap.
Ripping a board down will be just fine. When the planks gap out that much first thing i would do is clean the gap as much as possible. Im sure the inside edges are caked with gunk. Clean that well, glue in your wedge pieces, and finish away.

Are you refinishing the entire floor? Or just plan on finishing the wedge pieces? Its hard to tell but my guess is the exsisting finish looks like a varnish. With that in mind you cant put your typical polyurethane over varnish or shellac. It doesnt adhere properly and will just flake off. So you can find varnish still and i would use that if youre not up to the task to sand down to bare wood.

If you watch This Old House they did a show where they put pieces of rope between the planks. Looked ok. Not a fan personally but its another idea. Being the house is as old as it is you cant really go wrong looks wise.

Good luck!

Saw this done by a farmhouse owner and it looked OK. But, why would you want to do this in the first place? If it is more than simply cosmetic, such as reducing airflow from below, there are other ways to do that. If 'stuff' collecting in the cracks bothers your daughter, then any high suction vacuum cleaner with a crevice attachment can suck all that out in no time flat.

Another period-correct filling is oakum ... and it has the compressibility that wood strips don't have.

http://www.homedepot.com/p/t/202274121#product_description

Or rope, stained to match

http://www.thisoldhouse.com/toh/video/0,,1631562,00.html

OR - this is really radical ... the flexible gap-filler sold for the purpose
http://floormechanics.com/bona_pacific_filler_1_gallon-AF0001830-1.php

Thanks for all of the comments.

We have pulled up some of the boards over a crawl space to up-date the plumbing. I'm thinking that if the boards had moved due to shrinkage and swelling, they would have been split at the nails or the nails would have been loose. None of this happend. These boards were so tightly nailed that some were broken as we tried to get them out. Keep in mind that we are in central NYS and the humidity does not get up there too high.

I've cut a bunch of different sized splints and have tried them out and I think it's going to work. The spaces do have to be cleaned out as they are filled with all kinds of dirt, fur and anything else from nearly 200 years of use.

I'll be posting progressive photos so you can see how the project is going.

Thanks again.

Joe

This post was edited by joeurda on Tue, Feb 4, 14 at 13:51

I have seen on the internet where they have used rope to fill gaps. The rope is first measured by placing it in the gap to make sure it fits. Then it is taken out, stained and placed in the gap. Final step is the polyurethane. Looked beautiful in the videos.

I've been working on my daughter's dining room floors for about a week now and here is what I'm doing. There are 4 videos showing the steps I've taken to this point. They're not professional, but you can get an idea as to what it takes to get the job done. It's time consuming, but will be worth the effort.

Video 1 of 4 shows how I cleaned out nearly 200 years of dirt, fur and other junk. No gold dust yet.

Here is a link that might be useful: 1 of 4 Cleaning out the joints

Step 2 of 4 showing how I set in the splints in the joints.

Some of the joints vary in width, so I would have to use different sized splints.

Here is a link that might be useful: 2 of 4 - Setting in the splints

Step 3 of 4, hammering in the splints.

Some of the splints might get bashed in a bit, but not to worry. After leveling them off and sanding they are look great.

Here is a link that might be useful: Hammering in the splints.

Step 4 of 4 - Trimming off the splints. I tried different ways to take off the excess splint material and found that scribing the edges with my multi tool and then knocking them off with the hammer or chisel worked the best. Flushed them down to the level of the floorboards with a sander.

This is not the final video. Sanding them down, staining and sealing videos will follow.

Here is a link that might be useful: Trimming off the splints.