How to Cope Right-Angle Wood Joints in Carpentry

A coping saw features a thin blade for detailed cutting.

Many joints, such as dovetail, or mortise and tenon joints, are structural. In carpentry a coping joint is a non-structural decorative joint between two pieces of trim that make them appear as a continuous piece. A coped joint can only be used for inside corners and is installed by cutting the profile, or face design, into one piece of trim so it will fit smoothly against the face of a previously installed piece. Both miter and coping saws are needed to effectively make this joint.

Things You'll Need

• Molding
• Tape measure
• Miter saw
• Pencil
• Coping saw
• Sandpaper
• Finish nails
• Hammer

Instructions

1. Install the first piece of molding or trim, running into the corner with a square cut end. Measure the piece needed for the adjoining trim and cut it to length a few inches longer than needed.

2. Adjust the miter saw to a 45-degree miter. Stand the molding or trim to be cut with its back against the fence and the bottom edge flush on the saw's table. Make the cut through the height of the molding to reveal a cutaway of the molding's profile. The profile will be the edge of the design where the face of the molding breaks into the mitered face.

3. Rub the side of a pencil along this edge to make it stand out for cutting.

4. Place the molding flat on its back and clamp it in place so the mitered end with the highlighted detail line hangs off of the work table.

5. Cut along the line with a coping saw. Hold the saw upright so the blade passes through the molding on a 90-degree angle to the face of the molding. Cut along the line, staying as close to it as possible. Sand the cut edge lightly to smooth it with a piece of 100-grit sandpaper.

6. Fit the coped end to the face of the other piece of molding you installed in the corner. Sand any details that don't fit snugly. The joint should follow the face of the profile exactly. Cut the other end of your molding to the desired length with the miter saw and nail it in place with finish nails.

References

• "Ultimate Guide to Crown Molding;" Neal Barrett; Creative Homeowner, 2007
• This Old House: How to Cope a Joint for Crown Molding