How to Calculate Angle Cuts for Exterior Trim
- 1). Gauge the overall angle of the two meeting wall planes by positioning a bevel square's handle against one wall plane and pressing the blade against the adjacent wall, then tightening the square's hinge screw to lock the setting.
- 2). Define the overall angle by resting the base of a protractor on the handle of the bevel square and align the center point on the protractor's base with the inside corner of the bevel square's angle. The angle can be read at the point that the edge of the square's blade crosses the protractor's degree scale.
- 3). Divide the overall angle in half to determine the miter cut angle needed. For example: If the overall angle of the corner is 60 degrees, the miter cut for the corner would be two 30-degree angles. Use this formula to calculate the cuts for any mitered joint in your exterior trim.
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