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How to Cut Triangles With a Mitre Saw

Paul Massey

A triangle is defined as any three-sided polygon and it can be used to create many trim details. A miter saw can quickly set and cut accurate angles such as those required to cut a triangle. The procedure for setting up the miter saw and cutting a triangle with three equal sides, referred to as an "equilateral" triangle, is easy to complete. You can adapt the basic method to create any triangular shape.

A miter saw is the perfect tool for cutting decorative triangular shapes.
  1. Draw an outline of the desired triangle on a piece of graph paper. This defines the width of lumber needed for the triangle pieces and the accurate angles for the miter saw cuts.

  2. Determine the cut angles for the triangle using a protractor. Align the base edge with one side of the triangle, with the axis point on the point, and read the protractor scale to define the angle.

  3. Set the miter saw's adjustable arm to the degree mark that matches the angle determined in Step 2.

  4. Measure the length of the triangle's base or bottom side on the surface of the board at one edge.

  5. Position the board on the miter saw table, with the base side of the board against the saw fence. Set the miter angle on the saw to the angle determined in Step 2, align the saw blade with the appropriate mark on the board and cut the side of the triangle.

  6. Set the miter saw's cut angle to the same angle on the opposite side and align the blade with the mark on the board for the remaining angle cut. Cut the angle to complete the triangle-shaped piece.