Copied joints are generally preferred by trim carpenters and other professionals because they open up less than mitered joints when the wood shrinks during dry weather. Coped joints are also more forgiving of out-of-square wall corners than miters, which need a 90-degree corner for a flawless fit. Miter boxes available from most lumberyards have varying degrees of success at creating true miter cuts without human intervention, so this task should be left to a professional if you want your windows to match exactly.
The main advantage of coping over miter cutting is that you can get away with having slightly off-angle windows if you don't mind having some glue seep into the joint. The coped window seat shown in the photo below has an angle of about 1/4 degree. While this may not seem like much, it's enough to cause problems if the seat is going to face up or down because there will be gaps around the sides where the seats meet. The mitered window seat was actually cut at a slightly sharper angle (about 3/8 degree) which allows for better alignment between the seats.
Another advantage of coping is that you can use it on interior or exterior corners. Miters must be used exclusively on corners where the faces meet from room to room within the house. If you're not sure whether or not you should coped or mitered a particular window seat, ask someone who knows about these things to give you advice.
Coping is the preferred method for most interior trim. Yes, it's a little finicky—I occasionally have to back-cut the cope with a tool knife—but it always works. If an inner corner is not square, you must cut a miter under or over, and it may still open up over time. Inner corners are particularly prone to this problem because there's no way to see them until they're too late.
The best way to deal with an inner corner is to measure before you cut. Be sure to include the depth of any protruding items such as screws or bolts for reference when marking your cuts. It's also important to keep in mind that if an item is painted or covered with other materials, they will need to be removed before applying the copes. Painting or covering finishes can be renewed later but the coping itself cannot be reapplied once it's been removed. This is why it's important to check your corners before you start cutting!
After you've measured and marked your cuts, it's time to get out the tools. Start by ripping up one of the sides of the corner with a circular saw. Then come back and crosscut the other side of the corner with another rip cut. Finally, finish off the cut with a chisel or handsaw and then sand the area smooth. You should now have a perfectly flat and squared off corner!
In conclusion, coping is an essential part of giving old furniture a new life.
With a little piece of 120-grit sandpaper, sand over the miter. Sand across the joint, then sand remove any cross-grain sanding lines by sliding the paper with the grain in both directions. Sanding sawdust will combine with the glue to fill any minor gaps.
Follow up with a water rinse and let dry. The finished corner should look like new wood.
Rounded corners give a space a warm, adobe-like appearance and offer trimless open entrances a more polished appearance. Making a rounded, or bullnose, corner is simple if you prepare ahead of time. First, measure out the distance around the perimeter of the room about 1/4 inch greater than the wall thickness on all sides. Then, take a tape measure to any floor-to-ceiling interior corner and make sure it is level. Finally, cut two pieces of wood the length of the corner with a flat surface at one end. Nail them together with the smooth side facing out.
Now, you need to fill the gap between the walls and the floor with something. The most common option is to use caulk. But if you want to add a little style to your project, check out some of these options: Mudding walls before applying wallpaper or paint gives a clean finish that's easy to remove; consider using colored mud for a custom look. Or, opt for one of these unique options: Old barnboard can be reclaimed and refinished to create a rustic accent or filler piece for a wall void; consider adding texture by sanding old doors or furniture.
As you can see, there are many different options when it comes to finishing walls.