How to Cope Inside Molding

It's advisable to use coped miter cuts for inside corners when you are installing chair rails, baseboard or crown molding. Learning to use coped joints is an effective way to avoid being left with unsightly gaps in corner joints.

Difficulty: Moderate

Instructions

Things You'll Need:

• Miter saw
• Coping saw
• Combination round and flat-faced rasp
• "C" clamp
• Pencil
• Crown molding

Cut Inside Miter

1. 

   Using a miter saw or a back-saw with a miter box, cut an inside miter on the end of the crown molding to be used for the inside corner.

2. Smooth any rough edges using the flat-face rasp.

3. Review the cut to ensure the crown profile has been revealed by the miter cut.

Cope the Mitered Cut

4. 

   Trace a dark pencil line around the perimeter of the profile of molding that has been exposed by the miter cut.

5. Secure the mitered end firmly in a vice or clamp, with the mitered end in an accessible position.

6. 

   Starting from the back side of the top of the molding, begin cutting parallel to and 1/16 inch in from the drawn pencil line using a coping saw.

7. Continue cutting along the molding profile until it makes a change in direction the blade will not negotiate. At this point, remove the saw.

8. 

   Resume cutting by making a vertical cut perpendicular to the back of the molding and intersecting with the previous cut line. This will allow you to remove the previously cut wood.

9. 

   Begin a new cut on the opposite side of the vertical cut and continue cutting within 1/16 inch of the molding profile. If the profile angles become too sharp to negotiate, repeat Steps 4 and 5.

10. 

    Once the backside of the profile has been cut away, use the round-faced rasp to smooth out the rounded profile points and use the flat-faced rasp to remove excess wood from the sharper angles.

11. 

    Test-fit the molding to match molding previously nailed in place on the wall.

12. 

    Mark on the molding any point at which a gap is seen; at that point, use the rasp to remove additional wood on the back side of the molding.
    Repeat Steps 8 and 9 until no gap is seen.

Install Inside Corner

13. Matched the coped corner to the butt corner on the wall.

14. Prior to nailing in place, coat the coped surface with carpenter's glue.

15. Nail molding at the far end and in the middle before nailing the coped corner.

16. Fit the coped corner to the butt end on the wall and nail in place.

17. Remove any excess glue and allow to dry.
    Use fine-grade sandpaper to smooth the joint surface.

Tips & Warnings

• When cutting with a coping saw, it is important to stay within the pencil line outlining the molding profile. When coping, the saw must be tilted at an angle sufficient to back-cut and remove excess wood on the back side of the molding where it meets the crown profile revealed by the miter cut.