Lend a finished look to your moulding and trim with an outside miter cut
The biggest part of putting up moulding is not holding it in place and driving a nail every 16 inches. It's the few inches around the corners, that will require your greatest attention.
Miters are most easily cut on a power miter saw. The saw can be set to cut at any angle - set it to 45 degrees for a standard 90 degree corner. The saw can be set to 45 degrees to the left or 45 degrees to the right. So it's a little confusing at first, but once you get the hang of it, it's automatic.
Most people like to install moulding working from the left side of a wall to the right, and these directions assume that you will, too. It's hard to get a miter exactly where you want it to be on a board. When you're mitering, cut the miter on a piece a little bit longer than you'll need. Cut it to length by making a square cut. Before making any cuts, use a level and lightly mark a guideline for the moulding along the wall.
Before you begin cutting, consider:
• If cutting crown moulding, it’s a best practice to cut it upside down. Meaning the wall edge should be against the fence with the top edge on the saw bed.
• You can distinguish outside and inside corners from one another by following this simple guideline. On outside corners, the cut edge is hidden by the face of the moulding when looking head on. Inside corners show both the cut edge and finished face when looking head on.
• Wall corners are rarely a perfect 90 degrees. Always use a framing square or protractor/angle finder to find the true angle and adjust the miter cut accordingly.
This guide highlights the procedures for cutting and installing moulding with an outside mitered cut.
WHAT YOU NEED FOR THIS PROJECT
Start with two pieces of moulding, each a few inches longer than the section of wall they will cover. Set the saw blade 45 degrees to the right. Put the moulding that goes on the left-hand side of the corner against the fence to the left of the blade. Cut the moulding, leaving it long.
Turn the saw blade 45 degrees left. Put the second moulding to the right of the blade, and cut a miter in it that leaves the board longer than finished length.
The point of an outside miter sticks out beyond the corner by the thickness of a moulding. To get the right length moulding, measure the wall, add the thickness of the moulding, and make a mark that distance from the mitered point of the moulding. It's sometimes easier if you do it in steps, as was done in the photo. The moulding shown here runs along a short wall of an alcove, which measures 10 3/8 inches. The moulding is 1/2 inch thick. If you look closely, there's a light mark on the moulding at 10 3/8 inches; the second mark, which shows where to make the cut, was made by adding to that the thickness of the moulding.
Set the blade for a square cut (0 degrees), and lay the moulding on its back on the saw table. Cut the moulding at the line.
Test fit the pieces against the wall to check alignment. Nail one of the mouldings on the wall, dab wood glue into the mitered surface on the second piece, and nail it in place, too. Reinforce the joint by driving 1-inch brads through the faces of both mouldings, through the miter joint, and into the other moulding.