Hello! I have a poor friend with a pine plank floor from the 1870's that is worn out but he wants to keep it. It's past the point of sanding it as the tongue and groove system is failing in high traffic areas - back of groove cracked or that area missing. He has seen floors in the Washington DC area where they have installed brass plates in these areas as a repair and wants to me to do something like that. Seems like it would involve routing out the floor so that the pieces would be flush. He doesn't remember seeing screws in the plates so guessing they were epoxy'ed in place, but these floors aren't flat so was thinking to also screw in the plates. Anyone heard of something like this? I am familiar with the T-bar brass that is used to separate fields of flooring but not plates installed on the surface...

Thanks in advance for the brainwaves, Sean

When T&G floors become thin from sanding the top part of the groove gets weak and can splinter. If you like to keep the old floor I recommend installing a thin piece of blocking, one half inch thick plywood cut into 2 inch wide strips, glued between the floor joists to make the flooring move in unison so no more splintering happens. If it has already started, then it is important to do this if the underside of the flooring is still exposed, otherwise with normal traffic it will spread. Splinters can be dangerous. After the blocking has been done epoxy/wood flour can be used for a filler, or sometimes just wood putty, since the boards don't move enough for it to pop out after it gets hard.
You will need to get sheets of brass at the doorways fastened with screws or use construction adhesive with weight on it till the glue dries where the floor is splintering instead of trying to make it flush.