Foam molding is manufactured for crown molding, baseboard molding and for other decorative projects. Cutting foam molding is just as difficult as cutting wood or MDF molding: Getting the angles right is usually the hardest part. You also have to orient the cut on the foam molding in the correct manner or things will not line up. If you have never cut molding, or any other kind of finishing product, make a few practice cuts before you make any cuts in the molding. This will help you understand cut placement and the orientation of the molding with the saw blade. There are three basic cuts you will have to make: a scarf joint, an outside 90-degree angle, and an inside cope joint.
Mark the molding where the cut has to be made.
Place the first piece of foam molding tight against the miter saw fence. Rotate the saw blade 45 degrees to the right.
Cut the molding at the mark.
Mark the second piece of molding where the cut has to be made.
Flip it upside down and tight against the miter saw fence. Make the cut at the mark.
Test the fit to be sure it is tight.
Outside 90-degree cut
Mark the molding where the cut needs to be made. Rotate the miter saw blade so it is 45 degrees to the right.
Place the molding tightly against the miter saw fence. Line the blade up with the mark on the molding.
Cut the molding on the mark. Set the first piece of molding aside.
Mark the second piece of molding where the cut has to be made. Rotate the miter saw blade 90 degrees to the left.
Place the molding tightly against the miter saw fence. Line the saw blade up with the mark. Make the cut and test-fit the two pieces to be sure the joint is tight.
Inside coped cut
Square-cut the first piece of molding till it sits right in the corner.
Cut the second piece of molding at a 45-degree angle. Highlight the leading edge profile of the molding with a pencil.
Hold the molding firmly and use a coping saw to cut along the profile of the molding.
Sand the joint with 100-grit sandpaper if needed to create a tight fit.