Spring Angle

• The spring angle is the angle of the back of the molding when you hold it flush to the wall or ceiling. Spring angles are 45 degrees, 52 or 38 degrees. You do not need to cut this angle, but you do need to know it to set up your miter saw. Place the molding against a carpenter's square with the edges of the square substituting for the wall and ceiling. If the distance on both sides of the square is equal, you have a 45-degree spring angle; if not, it is a 52- or 38-degree angle.
  
  

Miter Saw Settings

• If your spring angle is 45 degrees, set the left bevel angle of your miter saw to 30 degrees and the left or right miter angle to 35.3 degrees. For a 52- or 38-degree spring angle, the left bevel setting is 33.9 degrees and the miter angle is set to 31.6 degrees.
  
  

Cutting 90-degree Inside Corners

• For the left side of an inside corner, set your miter saw to the correct bevel and miter angles based on your spring angle. Set the molding on the miter saw so the top side of the molding is turned to the fence of the saw. For the right inside corner cut, turn the molding so the bottom of the piece rests against the fence. For either cut, the extra molding should be to your right.
  
  

Cutting 90-degree Outside Corners

• To make the cut for the left side of an outside corner, set your miter saw to the correct bevel and miter angles depending on your spring angles. Set the molding on the miter saw so the bottom of the molding is turned to the fence of the saw. For the right inside corner cut, turn the molding so the top of the piece rests against the fence. For either cut, the extra molding should be to your left.