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How to Make Compound Cuts on Roof Trusses

Some roof trusses require you to line the chords and webbing up at different angles. For example, if you have a pyramid-shaped roof, creating standard gable trusses isn't going to do the trick. You must make a cut that creates two angles at once rather than a single-angle cut. A cut along more than one angle is called a compound cut, and is done with a compound miter saw.

Things You'll Need

  • Compound miter saw
  • Truss blueprints
  • 2-by-4 lumber
  • Tape measure
  • Ruler
  • Safety glasses
  • Hearing protection
  • Scientific calculator
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    • 1

      Consult your truss blueprints and select the piece you want to cut. For example, cut one of the top chords. The roof will have a 6:12 pitch, meaning that it rises 6 inches for 12 inches of run.

    • 2

      Input "6/12" in your calculator, then press "tan-1." This will give you the angle of the slope as 26.56 degrees.

    • 3

      Connect your miter saw and put on safety glasses and hearing protection if necessary.

    • 4

      Place the board's longest edge against the fence of the miter saw. The fence is a horizontal portion of the saw that provides a bracing point. Screw the clamps tightly to hold the wood in place.

    • 5

      Set the miter angle of the saw according to the measurement in Step 2. Use the miter gauge. Some miter saws will have a laser line that indicates where the blade will make contact.

    • 6

      Determine the angle you want to bevel the wood — 10 degrees, for example. Turn the saw blade on the vertical pivot until it matches 10 degrees.

    • 7

      Lock the blade in place, press the trigger and pull the saw onto the wood to make the cut.