Carpenters use miter cuts to join two boards at an angle. If a corner is exactly 90 degrees and you cut each piece of wood at a 45-degree angle, the pieces will meet in the middle. If the angle isn't exactly 90 degrees, you may need to cut an angle that's not quite 45 degrees to make the wood pieces meet. In either case, you can use a tape measure to mark the wood at the appropriate angle for the miter cut.
Things You'll Need
- Calculator or tangent table
Measure the width of the wood with a tape measure.
Measure that same distance back from the end of the wood on one side. Put a pencil mark there.
Align a straightedge between the pencil mark and the end of the wood on the other side. Draw a line along the straightedge. The result will be a line at a 45-degree angle. If you make the same cut on two pieces of wood, they should fit together inside the corner.
Other Inside Angle
Divide the angle by two.
Find the tangent of the result from step 1, using a calculator or table of tangents.
Measure the width of the wood with a tape measure. Divide the width of the wood by the tangent from step 2.
Measure that distance back from the end of the wood on one side. Put a pencil mark there.
Align a straightedge between the pencil mark and the end of the wood on the other side. Draw a line along the straightedge and cut the wood along the line. If you cut two pieces of wood at the same angle, they should fit together to match the desired angle of the corner.
Tips & Warnings
- Test the measurements by using them to cut two pieces of cardboard and making sure the cardboard fits the way you want before you cut the wood.
- Use a carpenter's angle divider to measure the angle against which you want to fit the boards.
- "Popular Mechanics"; Two Super Shop Ideas from Readers; December 1979
- "Mathematics for Plumbers and Pipefitters"; Lee Smith; 2003
- Photo Credit picture frame corner image by Jim Mills from Fotolia.com
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