Step 1
Cut each of the joint ends at a 45-degree angle by placing the molding on a miter saw in the same position it would be placed on the baseboard. If the inside corner is a perfect 90-degree angle, the two molding pieces will fit into the corner.
Step 2
Butt-cut, or straight-cut, one end of the molding by placing it on a miter saw and cutting at a 90-degree angle. For inside corners that are not 90 degrees, a carved joint end is fitted against a straight-cut end.
Step 3
Place the opposing end of the molding and cut it at a 45-degree angle on the miter saw. Cut the end that will meet the other end of the molding.
Step 4
Carve out the excess backing with a coping saw following the leading edge, or curved edge, of the molding.
Step 5
With a utility knife, scrape off any excess wood bits that prevent a perfect fit between the butt cut and coped edge of the two molding joints.